Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Obstetric risk indicators for labour dystocia in nulliparous women: A multi-centre cohort study

Obstetric risk indicators for labour dystocia in nulliparous women: A multi-centre cohort study Background: In nulliparous women dystocia is the most common obstetric problem and its etiology is largely unknown. The frequency of augmentation and cesarean delivery related to dystocia is high although it is not clear if a slow progress justifies the interventions. Studies of risk factors for dystocia often do not provide diagnostic criteria for the diagnosis. The aim of the present study was to identify obstetric and clinical risk indicators of dystocia defined by strict and explicit criteria. Methods: A multi-centre population based cohort study with prospectively collected data from 2810 nulliparous women in term spontaneous labour with a singleton infant in cephalic presentation. Data were collected by self-administered questionnaires and clinical data-records. Logistic regression analyses were used to estimate adjusted Odds Ratios (OR) and 95% confidence intervals (CI) are given. Results: The following characteristics, present at admission to hospital, were associated with dystocia during labour (OR, 95% CI): dilatation of cervix < 4 cm (1.63, 1.38–1.92), tense cervix (1.31, 1.04–1.65), thick lower segment (1.32, 1.09–1.61), fetal head above the inter-spinal diameter (2.29, 1.80–2.92) and poor fetal head-to-cervix contact (1.83, 1.31–2.56). The use of epidural analgesia (5.65, 4.33–7.38) was also associated with dystocia. Conclusion: Vaginal examinations at admission provide useful information on risk indicators for dystocia. The strongest risk indicator was use of epidural analgesia and if part of that is causal, it is of concern. process leading to delivery, especially when the fetal head Background It remains difficult to determine whether a period of slow is above the inter-spinal diameter and the fetal head-to- progress in labour is pathological and therefore justifies cervix contact is poor. treatment, or is a normal variation in the physiological Page 1 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 Most interventions during nulliparous labour use dystocia ing, singleton pregnancy, no planned elective cesarean as indication and about 50% of all cesarean deliveries are delivery or induction of labour. From inclusion at gesta- related to dystocia [1,2]. The term dystocia is used by tional week 33 to collection of baseline data in gestational some authors exclusively when immediate instrumental week 37, 202 women were excluded for the following rea- or cesarean delivery is indicated [1], while others, includ- sons: preterm delivery (n = 176), incorrect inclusion (n = ing ourselves, use the term when augmentation is needed 8), multiple pregnancy (n = 9), planned elective cesarean regardless of subsequent mode of delivery [3-6]. The inci- delivery or induction (n = 9). dence of dystocia is not well monitored and there is no consensus on the length of normal labour or the diagnos- Exclusion criteria at delivery were: > 42+0 weeks of gesta- tic criteria for dystocia [1,3,4,7-11]. An increase in the tion, induction, elective cesarean delivery and breech need for augmentation has been reported in affluent presentation (Figure 1). In total 1115 were excluded at countries and some studies show augmentation is now delivery. The reasons for exclusion were as follows: induc- used in around 50% of nulliparas [6,12-14]. tion (including post-term pregnancies) (n = 741), elective caesarean delivery (n = 84), breech presentation (n = 178) The reasons for the increased incidence of dystocia are and miscellaneous (n = 112). The latter comprised incor- only partly known. Poor head-to-cervix force may be asso- rect inclusion (e.g. non-Danish speaking, < 18 years at ciated with slow progress of labour [15,16], as may poor inclusion), foetus mortuus and unspecified. In addition engagement of fetal head at onset of labour [17]. High we excluded 138 with no civil registration number, as we fetal weight may increase the risk of dystocia [18-20], and would not be able to extract data from the Danish it is debated whether epidural analgesia in itself prolongs National Birth Register to validate their information. labour [18,21-27]. With the increasing age in nulliparous Incomplete sets of data (n = 560) were not included in the women, sub-fecundity is also more frequent and elevated analyses and 323 were lost to follow up due to an exces- risk of failure to progress was found in fertility-treated sive workload for the midwives (n = 274) and miscellane- pregnancies [18,28]. Iatrogenic factors have also been ous (moved or referred to a hospital outside the used to explain the increase in dystocia incidence, aug- participating hospitals, declining further participation mentation and cesarean delivery [29-32]. Most reported and unspecified, n = 49). associations between dystocia and obstetric risk factors are based on varying criteria for dystocia; often, no criteria Diagnostic criteria for dystocia are presented in Table 1. are given. We therefore conducted this study, based on These criteria are in accordance with guidelines from Dan- strict and explicit criteria, to identify obstetric and clinical ish Society of Obstetrics and Gynecology [34], supple- risk indicators for dystocia. mented with a criterion for the descending phase of labour's second stage from the guidelines on dystocia from the American College of Obstetrics and Gynecology Methods Data stem from the Danish Dystocia Study, a population [1]. To minimize potential misclassification of the dysto- based multi-centre study on incidence, risk indicators and cia diagnosis in our study, we performed systematic data women's experiences of labour with dystocia. Participants quality control measures to assess compliance with the were part of a fixed cohort of nulliparous women fol- protocol criteria. Dystocia was only given as a diagnosis if lowed from gestational week 37 through 2 weeks after the duration of labour exceeded the cut-off times of the delivery [33]. The final study population comprised 2810 criteria in Table 1. Women who received augmentation nulliparous women who delivered a singleton infant in without fulfilling the study criteria for dystocia (n = 299) cephalic presentation at term after spontaneous onset of were retained in the population at risk. The dystocia diag- labour. The study was restricted to these nulliparas to nosis was not given to women with absence of contrac- reduce co-morbidity that could justify induction or a tions after prelabour rupture of membranes (PROM) planned cesarean delivery. according to the coding guideline of obstetric interven- tions in Denmark since treatment of PROM is classified as Inclusion into the study took place between May 2004 induction of labour [35]. and July 2005. Participants were recruited from four major university hospitals, three county hospitals and two Exposure data were collected prospectively. Data collec- local district departments with annual birth rates varying tion was based on a self-administered questionnaire com- between 850 and 5400. Recruitment took place in the pleted in gestational week 37. Data records were antenatal clinics at 33 gestational weeks and baseline completed by the assisting obstetric staff at the woman's information was collected at 37 gestational weeks. In admission to the labour ward, and during and after order to have a well defined group with no obvious risk labour. Local contact persons at the participating centres factors for dystocia, the following inclusion criteria were undertook close supervision during follow-up in all used: nulliparas, 18 years of age or older, Danish speak- phases of the data collection. Page 2 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 Inclusion: E ligible G estational w eek 33 8099 N ot invited 1743 /8099 (21.5 % ) Invited 6356/8099 (78.5 % ) R efused participation 872/6356 (13.7 % ) A ccepted participation 5484/6356 (86.3 % ) E xcluded in pregnancy * 202 /5484 (3.7 % ) Baseline: Participants at term G estational w eek 37 5282/5484 (96.3 % ) Pregnancy questionnaire Pregnancy questionnaires not returned 336 /5282 (6.3 % ) Pregnancy questionnaires returned from participants at term 4946/5282 (93.6 % ) Excluded at delivery * 1115 /4946 (22.5 % ) E xcluded due to m issing civil registration num ber 138/4946 (2.6 % ) Follow -up: D elivery and post partum To follow -up Four data records and 3693/4946 (74.7 % ) postpartum questionnaire L ost to follow -up 323/3693 (8.7 % ) Incom plete sets of data records and post partum questionnaires† 560/3693 (15.1 % ) Sets of data records and questionnaires for analyses of Incidence , outcom es and risk indicators 2810/3693 (76.0 % ) *E xclusion criterea: < 37 or > 42 gestational w eeks, m ultiple pregnancy , breech presentation, elective cesarean delivery, induction and incorrect inclusion into the study †Incom plete sets of data records and post partum questionnaires usable for analyses in som e substudies of The D anish D ystocia Study Th Figure 1 e Danish Dystocia Study Flowchart The Danish Dystocia Study Flowchart. Page 3 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 Table 1: Definitions of Stages and Phases of Labour and Diagnostic Criteria for Dystocia Stage of labour Definition of stage and phase Diagnostic Criteria for Dystocia First stage From onset of regular contractions leading to cervical dilatation to full dilatation of cervix Latent phase Cervix 0 – 3.9 cm dilatation The diagnosis was not to be given in this phase Active phase Cervix ≥ 4 cm dilatation < 1/2 cm dilatation of cervix per hour, assessed over 4 hours = dystocia Second stage From full dilatation of cervix to the child is born Descending phase From full dilatation of cervix to strong > 2 hours without descent = dystocia. and irresistible urge to push If epidural is administered: > 3 hours = dystocia Expulsive phase Strong and irresistible pushing during the > 1 hour without progress = dystocia major part of the contraction The examined risk indicators of dystocia were: dilatation confidence intervals (CI). Adjustments were made for age and consistency of cervix, thickness of lower segment, in four groups (< 25, 25–29, 30–34, 35+), height in three descent of fetal head and fetal head-to-cervix contact at groups (< 160, 160–169, 170+), pre-pregnancy BMI in admission to the delivery ward, infertility prior to current five groups (< 18.5, 18.5–24.9, 25.0–29.9, 30+) and level pregnancy and use of epidural analgesia. Measurements of of physical activity in first trimester in four groups (regular lower uterine segment, cervix and fetal head conditions intensive physical training and competitive sports several were performed manually during routine vaginal exami- times/week, athletics or heavy physical activity ≥ 4 hours/ nations. In the pilot phase of the study two methods of week, light physical activity ≥ 4 hours/week, predomi- validation of vaginal examinations were considered: use nantly sedentary lifestyle) as these potential confounders of a model or an additional examination by a second mid- may be independent risk factors for dystocia, and some wife. Both methods were discarded as constituting an are known to interact with the risk factors under study, i.e. unacceptable extra workload and also, in the case of the BMI and birth weight and age and infertility. Age, height, latter, for ethical reasons. We assumed that the weight of pre-pregnancy BMI and level of physical activity were ini- the expected child plays a role in the progress of labour. tially all included in the model and subsequently deleted However, the actual weight of the expected child is one by one with replacement. None of the variables unknown and cannot with accuracy be taken into consid- changed the estimate by more than 10% but we decided eration for potential clinical management of the labour. to keep all variables in the model since they did not Our analyses included as well as excluded, respectively, increase the variance of the OR. We also estimated OR for birth weight in the regression model to examine the effect the clinical risk indicators with all variables included in of birth weight on the clinical risk indicators. the model to adjust for their mutual associations and to identify which factors had the strongest independent asso- Prior to analyses, dilatation of cervix and birth weight ciation. We calculated trend values for continuous varia- were categorized according to predefined categories. If bles (cervix dilatation and birth weight) by using logistic epidural analgesia was applied after dystocia was diag- regression. Odds ratio for trend represent a change in OR nosed and augmentation was initiated (n = 47), women per unit increase or decrease in the exposures under study. were excluded from the risk analyses. The categories of In order to take into consideration potential clinical and risk indicators are described in Table 2. social characteristics of the nine participating centres, we adjusted all analyses by including study centre in the Ethics model as a dummy variable. Descriptive statistics for con- Since no invasive procedures were applied in the study, no tinuous variables are presented as means with 95% CI or Ethics Committee System approval was required by Dan- medians (Inter-quartile range (IQR)) depending on distri- ish law. The policy of the Helsinki Declaration was fol- butional characteristics. lowed throughout the data collection and analyses. Written consent was obtained and person-specific data Statistical analyses were performed using SPSS 14.0 soft- were protected by codes. Permission to establish the data- ware (SPSS Inc., Chicago, Il). base was obtained from the Danish Data Protection Agency j. no. 2004-41-3995. Results The mean maternal age was 28.7 years (95% CI; 28.5 – Statistical methods 28.8) at entry into the cohort, but women with dystocia Binary logistic regression analyses were used to estimate were slightly older (29.1 yrs.). Median pre-pregnancy BMI crude and adjusted odds ratio (OR) for dystocia with 95% was 22.3 (IQR 4.2) with no significant difference between Page 4 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 Table 2: Odds Ratios for dystocia with 95% confidence intervals according to obstetric characteristics N 2810 Un-adjusted Adjusted OR* All variables All variables included Trend† OR OR (95% CI) included except birth weight (95% CI) Infertility treatment prior to current pregnancy No 2449 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Yes 184 1.13 0.95 (0.69–1.31) 0.92 (0.65–1.29) 1.09 (0.78–1.53) Missing 177 Dilatation of cervix at admission 0.83 (0.80–0.86) 0–3 cm 1086 1.67 1.63 (1.38–1.92) 1.29 (1.06–1.57) 1.21 (1.00–1.47) 4–10 cm 1575 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Missing 149 Consistency of cervix at admission Tense 585 1.25 1.31 (1.04–1.65) 1.0 (0.79–1.26) 0.98 (0.79–1.23) Soft 1794 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Missing 431 Thickness of lower segment at admission Thick 583 1.30 1.32 (1.09–1.61) 0.88 (0.69–1.12) 0.91 (0.72–1.14) Thin 1712 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Missing 515 Descent of fetal head at admission Above the inter-spinal-line 2367 2.33 2.29 (1.80–2.92) 1.80(1.32–2.45) 1.92 (1.42–2.58) At or under the inter-spinal-line 311 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Missing 132 Fetal head-to-cervix contact Good 1921 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Poor 159 1.88 1.83 (1.31–2.56) 1.62 (1.09–2.40) 1.57 (1.08–2.27) Cannot be assessed 455 Missing 275 Birth weight 1.001 (1.00–1.00) 2000–2499 gr 23 0.14 0.14 (0.32–0.60) 0.27 (0.61–1.21) 2500–2999 gr 282 0.57 0.51 (0.38–0.69) 0.55 (0.40–0.77) 3000–3499 gr 1040 0.78 0.74 (0.62–0.89) 0.76 (0.62–0.93) 3500–3999 gr 1016 1 (ref.) 1 (ref.) 1 (ref.) 4000–4499 gr 392 1.23 1.29 (1.02–1.65) 1.06 (0.83–1.41) ≥ 4500 gr 53 1.36 1.37 (0.78–2.41) 1.32 (0.70–2.46) Epidural analgesia No epidural 2284 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Epidural analgesia 316 5.49 5.65 (4.33–7.38) 4.65 (3.53–6.13) 4.77 (3.65–6.22) * Crude Odds Ratios controlled for age, height, pre-pregnancy BMI and physical activity, including a variable for the participating departments (9 levels). † Test for trend performed on continuous variables. First line: Regression coefficient for change in OR per unit increased, second line: 95% CI. the two groups. In this population 84% were non-smok- (part of the same manifestation) and when we included ers and 66% were engaged in light physical activity > 4 all variables from Table 2 in the statistical model, most hours per week. estimates were attenuated as expected. After mutual adjustments the estimates that remained strongest were Table 2 presents the unadjusted and adjusted OR within epidural analgesia, descent of fetal head above the inter- categories of obstetric risk indicators. Among the risk indi- spinal diameter, poor fetal head-to-cervix contact and dil- cators recorded at the woman's admission to the delivery atation of cervix < 4 cm at admission. ward, cervix dilatation < 4 cm, descent of fetal head above the inter-spinal level and poor fetal head-to-cervix contact Expecting a child with a birth weight < 3500 gr. appeared had the strongest association with dystocia. to be protective for dystocia while expecting a child with a birth weight > 4000 gr. was associated with increased risk Epidural analgesia was also strongly associated with dys- of dystocia compared to birth weights 3500–3999 gr. The tocia. The variables related to cervix are closely correlated last column presents OR without birth weight included in Page 5 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 the statistical model. Birth weight appeared to have a of epidural analgesia on the course of labour and delivery minor effect on OR and confidence intervals of the clinical and maternal and fetal outcomes [18,21-27]. Lower risk indicators. plasma oxytocin levels are found in women with epidural analgesia [40] and this may slow the progress of labour. Alehagen et al. found that women who received epidural Discussion The vaginal examinations at the woman's admission to analgesia had experienced more fear, but not more pain, the labour ward provided several prognostic indicators of before the administration of epidural analgesia than did dystocia later in labour. Expecting a child with a high birth women who did not receive epidural analgesia [41] and weight and the use of epidural analgesia were also associ- fear may prolong duration of labour [42]. Recent reviews ated with the risk of dystocia, the latter association being come to the conclusion that epidural analgesia appears to particularly strong. prolong labour's second stage and prompt more use of oxytocin [25-27]. Although we excluded from the analy- Fetal head above the inter-spinal diameter had the strong- ses those who were treated with epidural analgesia after est association with dystocia among the factors present at being diagnosed with dystocia, reverse causation is still a admission of women in labour, also in the analyses that possible explanation of the association we find. If a need excluded birth weight. Others have found that lack of for pain relief or fear of pain are among the clinical pre- descent of fetal head often leads to cesarean delivery for cursors of dystocia, epidural analgesia could be part of the dystocia [17,36]. Descent of fetal head is correlated to dil- mechanism leading to dystocia. atation of the cervix, and cervix dilatation < 4 cm at admis- sion was associated with an increased risk of dystocia. We were not able to replicate findings of an association Women admitted with little cervical dilatation may have between dystocia and infertility treatment prior to the cur- unbearably painful contractions. Anxiety may play a role rent pregnancy, perhaps because our statistical power to for early admission as well as concern for high maternal detect such an association is low. Others have demon- blood pressure, fetal heart rates or other clinical condi- strated a near doubling of the risk of failure to progress in tions. High risk of dystocia in women admitted in early treated women [18]. labour has also been found other studies [29,30,37,38], perhaps because early admission introduces risk of iatro- Our findings of an association between high birth weight gene-induced treatments [29,30]. We believe, however, (4000–4499 gr.) and dystocia corroborate findings from that quality control of our data prior to analyses ensured other studies even though the definition of 'high birth that the dystocia diagnosis was registered exclusively in weight' varies [19,20,22]. Although the birth weight can women who met the criteria. We therefore assume that only be estimated before the child is born, the clinical iatrogenic factors have not played a major role in our find- implication of our findings could be that increased risk of ings. dystocia should be considered when an estimated birth weight is more than 4000 gr. A poor fetal head-to-cervix contact at admission was asso- ciated with near doubling of the odds of dystocia. Gough Our findings of association between the clinical condi- et al. found that low head-to-cervix force was associated tions dilatation of cervix, descent of fetal head and fetal with poor progress and delivery by cesarean section for head-to-cervix contact and dystocia may have significant dystocia [39]. Allman et al. examined the head-to-cervix clinical implications. Women admitted to hospital for force electronically and advocate that head-to-cervix force delivery have a vaginal examination upon admittance and is a better predictor of the likely rate of cervical dilatation information from this examination provides the clinical than intrauterine pressure and also a better predictor of basis for the primary management of labour. Weight of mode of delivery than the dilatation rate itself [15,16]. the child appears to have only minor effect on the OR Our findings based on manual assessments during vaginal related to the clinical conditions. examinations support Allman's findings of an association between poor head-to-cervix contact and dystocia. Strengths and limitations The study has limitations. We reached 78.5% of the Epidural analgesia had the strongest association with dys- women eligible for inclusion in the study and of these tocia among the risk indicators assessed. In total 71.2% of 86.3% accepted the invitation to participate. Missed inclu- women who were treated with epidural analgesia were sions were mainly a problem during the first months of diagnosed with dystocia. A similarly strong association data collection and we have no reason to believe that this between dystocia and epidural analgesia was reported led to over-sampling of women with low or high risk of from a population-based study of 106,755 deliveries dystocia as inclusion took place 6–8 weeks before deliv- without induction and with durations of delivery < 12 ery. Almost nine percent were lost to follow up, possibly hours [14], but the literature is inconsistent on the effects related to the extra work required from the participating Page 6 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 departments. The aims of the Danish Dystocia Study were commented on. All authors approved the final manu- descriptive as well as analytical and the data collection script. instruments comprised four detailed data records to be filled in by the obstetric staff during the woman's stay at Acknowledgements Christina Vestergaard is thanked for assistance in processing data and Steen the delivery ward. It may be that the mere burden of work Rasmussen for data extraction from the Danish Medical Birth Register. gave rise to some non-responses to items or non-comple- tion of entire data records. However, we have no reason to References assume that non-responses were directly related to risk of 1. American College of Obstetrics and Gynecology. ACOG Practice dystocia. Bulletin Number 49, December 2003: Dystocia and augmenta- tion of labor. Obstet Gynecol 2003, 102:1445-1454. 2. Gifford DS, Morton SC, Fiske M, Keesey J, Keeler E, Kahn KL: Lack We did not include an independent criterion for dystocia of progress in labor as a reason for cesarean. Obstet Gynecol based on descent of the fetal head and cases with a quick 2000, 95:589-595. 3. Foley ME, Alarab M, Daly L, Keane D, Rath A, O'Herlihy C: The con- descent but a slow dilatation may have been classified as tinuing effectiveness of active management of first labor, dystocia. We recommend that future studies make it pos- despite a doubling in overall nulliparous cesarean delivery. sible to identify this group. Evaluation of cervical condi- Am J Obstet Gynecol 2004, 191:891-895. 4. Sosa CG, Balaguer E, Alonso JG, Panizza R, Laborde A, Berrondo C: tions and descent of fetal head is difficult and subject to Meperidine for dystocia during the first stage of labor. A ran- considerable intra- and inter observer variation. We rec- domized controlled trial. Am J Obstet Gynecol 2004, 191:1212-1218. ommend that further studies include different methods of 5. Cluett ER, Pickering RM, Getliffe K, St George Saunders NJ: Ran- measuring conditions related to the cervix and the fetal domised controlled trial of labouring in water compared head (i.e. electronic monitoring). with standard of augmentation for management of dystocia in first stage of labour. BMJ 328(7435):314. 2004 Feb 7; Epub 2004 Jan 26 The study also has important strengths. The population 6. Treacy A, Robson M, O'Herlihy C: Dystocia increases with based cohort design, based upon primary and prospec- advancing maternal age. Am J Obstet Gynecol 2006, 195:760-763. 7. Friedman E: Labor, clinical evaluation and management 2nd edition. New tively collected data, is a strength. The risk of differential York: Appleton-Century-Crofts; 1978. misclassification was reduced as we used prospectively 8. Vahratian A, Troendle JF, Siega-Riz AM, Zhang J: Methodological challenges in studying labour progression in contemporary collected data on cervix and fetal head conditions and the practice. Paediatr Perinat Epidemiol 2006, 20:72-78. study was based on strict diagnostic criteria agreed upon 9. Greenberg MB, Cheng YW, Hopkins LM, Stotland NE, Bryant AS, by all. Central as well as local supervisors took part in all Caughey AB: Are there ethnic differences in the length of labor? Am J Obstet Gynecol 2006, 195:743-748. phases of the data collection. 10. Zhu BP, Grigorescu V, Le T, Lin M, Copeland G, Barone M: Labor dystocia and its association with interpregnancy interval. Am J Obstet Gynecol 2006, 195:121-128. Conclusion 11. Turcot L, Marcoux S, Fraser WD: Multivariate analysis of risk Our study contributes further evidence of an increased factors for operative delivery in nulliparous women. Cana- risk of dystocia in nulliparous women who, at admission dian Early Amniotomy Study Group. Am J Obstet Gynecol 1997, 176:395-402. to hospital, present with a descent of fetal head above the 12. Danish Medical Birth Register [http://www.sst.dk] inter-spinal diameter and a cervix dilatation < 4 cm. We 13. Blix E, Pettersen SH, Eriksen H, Royset B, Pedersen EH, Oian P: [Use found that a tense cervix, a thick lower segment and a of oxytocin augmentation after spontaneous onset of labor]. Tidsskr Nor Laegeforen 2002, 122:1359-1362. poor contact between the fetal head and the cervix are risk 14. Oscarsson ME, Ahmer-Wåhlin I, Rydhstroem H, Kallen K: Outcome indicators for dystocia. Further studies should examine if in obstetric care related to oxytocin use. A population-based study. Acta Obstet Gynecol Scand 2006, 85:1094-1098. fetal head-to-cervix contact is a significant predictor of 15. Allman AC, Genevier ES, Johnson MR, Steer PJ: Head-to-cervix dystocia and if differentiation of the management of dys- force: an important physiological variable in labour. 2. Peak tocia can be based on assessment of fetal head-to-cervix active force, peak active pressure and mode of delivery. Br J Obstet Gynaecol 1996, 103:769-775. contact. The observed association between epidural anal- 16. Allman AC, Genevier ES, Johnson MR, Steer PJ: Head-to-cervix gesia and increased risk of dystocia is of interest and may force: an important physiological variable in labour. 1. The have a causal explanation. temporal relation between head-to-cervix force and intrau- terine pressure during labour. Br J Obstet Gynaecol 1996, 103:763-768. Competing interests 17. Roshanfekr D, Blakemore KJ, Lee J, Hueppchen NA, Witter FR: Sta- tion at onset of active labor in nulliparous patients and risk The authors declare that they have no competing interests. of cesarean delivery. Obstet Gynecol 1999, 93:329-331. 18. Sheiner E, Levy A, Feinstein U, Hallak M, Mazor M: Risk factors and Authors' contributions outcome of failure to progress during the first stage of labor: a population-based study. Acta Obstet Gynecol Scand 2002, HK and AKD planned the study. HK carried out the data 81:222-226. collection. Analyses were planned by HK, JO and PN. PN 19. Sheiner E, Levy A, Feinstein U, Hershkovitz R, Hallak M, Mazor M: conducted the data validation. HK conducted the analy- Obstetric risk factors for failure to progress in the first ver- sus the second stage of labor. J Matern Fetal Neonatal Med 2002, ses. HK, BO, AKD and JO interpreted the results. HK wrote 11:409-413. the drafts of the manuscript, which the other authors 20. Mocanu EV, Greene RA, Byrne BM, Turner MJ: Obstetric and neo- natal outcome of babies weighing more than 4.5 kg: an anal- ysis by parity. Eur J Obstet Gynecol Reprod Biol 2000, 92:229-233. Page 7 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 21. Feinstein U, Sheiner E, Levy A, Hallak M, Mazor M: Risk factors for http://www.biomedcentral.com/1471-2393/8/45/prepub arrest of descent during the second stage of labor. Int J Gynae- col Obstet 2002, 77:7-14. 22. Schiessl B, Janni W, Jundt K, Rammel G, Peschers U, Kainer F: Obstetrical parameters influencing the duration of the sec- ond stage of labor. Eur J Obstet Gynecol Reprod Biol 2005, 118:17-20. 23. Fraser WD, Cayer M, Soeder BM, Turcot L, Marcoux S: Risk factors for difficult delivery in nulliparas with epidural analgesia in second stage of labor. Obstet Gynecol 2002, 99:409-418. 24. Zhang J, Yancey MK, Klebanoff MA, Schwarz J, Schweitzer D: Does epidural analgesia prolong labor and increase risk of cesar- ean delivery? A natural experiment. Am J Obstet Gynecol 2001, 185:128-134. 25. Anim-Somuah M, Smyth R, Howell C: Epidural versus non-epi- dural or no analgesia in labour. Cochrane Database Syst Rev 2005:CD000331. 26. Leighton BL, Halpern SH: The effects of epidural analgesia on labor, maternal, and neonatal outcomes: a systematic review. Am J Obstet Gynecol 2002, 186:S69-S77. 27. Lieberman E, O'donoghue C: Unintended effects of epidural analgesia during labor: a systematic review. Am J Obstet Gynecol 2002, 186:S31-S68. 28. Tanbo T, Dale PO, Lunde O, Moe N, Abyholm T: Obstetric out- come in singleton pregnancies after assisted reproduction. Obstet Gynecol 1995, 86:188-192. 29. Bailit JL, Dierker L, Blanchard MH, Mercer BM: Outcomes of women presenting in active versus latent phase of spontane- ous labor. Obstet Gynecol 2005, 105:77-79. 30. Rahnama P, Ziaei S, Faghihzadeh S: Impact of early admission in labor on method of delivery. Int J Gynaecol Obstet 2006, 92:217-220. 31. Johanson R, Newburn M, Macfarlane A: Has the medicalisation of childbirth gone too far? BMJ 2002, 324:892-895. 32. Bell JS, Campbell DM, Graham WJ, Penney GC, Ryan M, Hall MH: Can obstetric complications explain the high levels of obstet- ric interventions and maternity service use among older women? A retrospective analysis of routinely collected data. BJOG 2001, 108:910-918. 33. Kjærgaard H: Dystocia in nulliparous women. Incidence, out- comes, risk indicators and women's experiences. In PhD thesis Lund University, Department of Health Sciences, Faculty of medicine, Sweden; 2007. 34. Danish Society of Obstetrics and Gynecology [http:// www.dsog.dk] 35. Coding guidelines of obstetric interventions in Denmark [http://www.dsog.dk/files/Obstetriske_koder_10112005.pdf] 36. Falzone S, Chauhan SP, Mobley JA, Berg TG, Sherline DM, Devoe LD: Unengaged vertex in nulliparous women in active labor. A risk factor for cesarean delivery. J Reprod Med 1998, 43:676-680. 37. Holmes P, Oppenheimer LW, Wen SW: The relationship between cervical dilatation at initial presentation in labour and subsequent intervention. BJOG 2001, 108:1120-1124. 38. McNiven PS, Williams JI, Hodnett E, Kaufman K, Hannah ME: An early labor assessment program: a randomized, controlled trial. Birth 1998, 25:5-10. 39. Gough GW, Randall NJ, Genevier ES, Sutherland IA, Steer PJ: Head- to-cervix forces and their relationship to the outcome of labor. Obstet Gynecol 1990, 75:613-618. 40. Rahm VA, Hallgren A, Hogberg H, Hurtig I, Odlind V: Plasma oxy- tocin levels in women during labor with or without epidural Publish with Bio Med Central and every analgesia: a prospective study. Acta Obstet Gynecol Scand 2002, scientist can read your work free of charge 81:1033-1039. 41. Alehagen S, Wijma B, Lundberg U, Wijma K: Fear, pain and stress "BioMed Central will be the most significant development for hormones during childbirth. Journal of Psychosomatic Obstetrics disseminating the results of biomedical researc h in our lifetime." and Gynecology 2005, 26:153-165. Sir Paul Nurse, Cancer Research UK 42. Lederman RP, Lederman E: The relationship of maternal anxi- ety, plasma catecholamines and plasma cortisol to progress Your research papers will be: in labor. Am J Obstet Gynecol 1978, 132:495-500. available free of charge to the entire biomedical community peer reviewed and published immediately upon acceptance Pre-publication history cited in PubMed and archived on PubMed Central The pre-publication history for this paper can be accessed yours — you keep the copyright here: BioMedcentral Submit your manuscript here: http://www.biomedcentral.com/info/publishing_adv.asp Page 8 of 8 (page number not for citation purposes) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png BMC Pregnancy and Childbirth Springer Journals

Obstetric risk indicators for labour dystocia in nulliparous women: A multi-centre cohort study

Loading next page...
 
/lp/springer-journals/obstetric-risk-indicators-for-labour-dystocia-in-nulliparous-women-a-0oD5fgG1cR

References (46)

Publisher
Springer Journals
Copyright
Copyright © 2008 by Kjærgaard et al; licensee BioMed Central Ltd.
Subject
Medicine & Public Health; Reproductive Medicine; Maternal and Child Health; Gynecology
eISSN
1471-2393
DOI
10.1186/1471-2393-8-45
pmid
18837972
Publisher site
See Article on Publisher Site

Abstract

Background: In nulliparous women dystocia is the most common obstetric problem and its etiology is largely unknown. The frequency of augmentation and cesarean delivery related to dystocia is high although it is not clear if a slow progress justifies the interventions. Studies of risk factors for dystocia often do not provide diagnostic criteria for the diagnosis. The aim of the present study was to identify obstetric and clinical risk indicators of dystocia defined by strict and explicit criteria. Methods: A multi-centre population based cohort study with prospectively collected data from 2810 nulliparous women in term spontaneous labour with a singleton infant in cephalic presentation. Data were collected by self-administered questionnaires and clinical data-records. Logistic regression analyses were used to estimate adjusted Odds Ratios (OR) and 95% confidence intervals (CI) are given. Results: The following characteristics, present at admission to hospital, were associated with dystocia during labour (OR, 95% CI): dilatation of cervix < 4 cm (1.63, 1.38–1.92), tense cervix (1.31, 1.04–1.65), thick lower segment (1.32, 1.09–1.61), fetal head above the inter-spinal diameter (2.29, 1.80–2.92) and poor fetal head-to-cervix contact (1.83, 1.31–2.56). The use of epidural analgesia (5.65, 4.33–7.38) was also associated with dystocia. Conclusion: Vaginal examinations at admission provide useful information on risk indicators for dystocia. The strongest risk indicator was use of epidural analgesia and if part of that is causal, it is of concern. process leading to delivery, especially when the fetal head Background It remains difficult to determine whether a period of slow is above the inter-spinal diameter and the fetal head-to- progress in labour is pathological and therefore justifies cervix contact is poor. treatment, or is a normal variation in the physiological Page 1 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 Most interventions during nulliparous labour use dystocia ing, singleton pregnancy, no planned elective cesarean as indication and about 50% of all cesarean deliveries are delivery or induction of labour. From inclusion at gesta- related to dystocia [1,2]. The term dystocia is used by tional week 33 to collection of baseline data in gestational some authors exclusively when immediate instrumental week 37, 202 women were excluded for the following rea- or cesarean delivery is indicated [1], while others, includ- sons: preterm delivery (n = 176), incorrect inclusion (n = ing ourselves, use the term when augmentation is needed 8), multiple pregnancy (n = 9), planned elective cesarean regardless of subsequent mode of delivery [3-6]. The inci- delivery or induction (n = 9). dence of dystocia is not well monitored and there is no consensus on the length of normal labour or the diagnos- Exclusion criteria at delivery were: > 42+0 weeks of gesta- tic criteria for dystocia [1,3,4,7-11]. An increase in the tion, induction, elective cesarean delivery and breech need for augmentation has been reported in affluent presentation (Figure 1). In total 1115 were excluded at countries and some studies show augmentation is now delivery. The reasons for exclusion were as follows: induc- used in around 50% of nulliparas [6,12-14]. tion (including post-term pregnancies) (n = 741), elective caesarean delivery (n = 84), breech presentation (n = 178) The reasons for the increased incidence of dystocia are and miscellaneous (n = 112). The latter comprised incor- only partly known. Poor head-to-cervix force may be asso- rect inclusion (e.g. non-Danish speaking, < 18 years at ciated with slow progress of labour [15,16], as may poor inclusion), foetus mortuus and unspecified. In addition engagement of fetal head at onset of labour [17]. High we excluded 138 with no civil registration number, as we fetal weight may increase the risk of dystocia [18-20], and would not be able to extract data from the Danish it is debated whether epidural analgesia in itself prolongs National Birth Register to validate their information. labour [18,21-27]. With the increasing age in nulliparous Incomplete sets of data (n = 560) were not included in the women, sub-fecundity is also more frequent and elevated analyses and 323 were lost to follow up due to an exces- risk of failure to progress was found in fertility-treated sive workload for the midwives (n = 274) and miscellane- pregnancies [18,28]. Iatrogenic factors have also been ous (moved or referred to a hospital outside the used to explain the increase in dystocia incidence, aug- participating hospitals, declining further participation mentation and cesarean delivery [29-32]. Most reported and unspecified, n = 49). associations between dystocia and obstetric risk factors are based on varying criteria for dystocia; often, no criteria Diagnostic criteria for dystocia are presented in Table 1. are given. We therefore conducted this study, based on These criteria are in accordance with guidelines from Dan- strict and explicit criteria, to identify obstetric and clinical ish Society of Obstetrics and Gynecology [34], supple- risk indicators for dystocia. mented with a criterion for the descending phase of labour's second stage from the guidelines on dystocia from the American College of Obstetrics and Gynecology Methods Data stem from the Danish Dystocia Study, a population [1]. To minimize potential misclassification of the dysto- based multi-centre study on incidence, risk indicators and cia diagnosis in our study, we performed systematic data women's experiences of labour with dystocia. Participants quality control measures to assess compliance with the were part of a fixed cohort of nulliparous women fol- protocol criteria. Dystocia was only given as a diagnosis if lowed from gestational week 37 through 2 weeks after the duration of labour exceeded the cut-off times of the delivery [33]. The final study population comprised 2810 criteria in Table 1. Women who received augmentation nulliparous women who delivered a singleton infant in without fulfilling the study criteria for dystocia (n = 299) cephalic presentation at term after spontaneous onset of were retained in the population at risk. The dystocia diag- labour. The study was restricted to these nulliparas to nosis was not given to women with absence of contrac- reduce co-morbidity that could justify induction or a tions after prelabour rupture of membranes (PROM) planned cesarean delivery. according to the coding guideline of obstetric interven- tions in Denmark since treatment of PROM is classified as Inclusion into the study took place between May 2004 induction of labour [35]. and July 2005. Participants were recruited from four major university hospitals, three county hospitals and two Exposure data were collected prospectively. Data collec- local district departments with annual birth rates varying tion was based on a self-administered questionnaire com- between 850 and 5400. Recruitment took place in the pleted in gestational week 37. Data records were antenatal clinics at 33 gestational weeks and baseline completed by the assisting obstetric staff at the woman's information was collected at 37 gestational weeks. In admission to the labour ward, and during and after order to have a well defined group with no obvious risk labour. Local contact persons at the participating centres factors for dystocia, the following inclusion criteria were undertook close supervision during follow-up in all used: nulliparas, 18 years of age or older, Danish speak- phases of the data collection. Page 2 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 Inclusion: E ligible G estational w eek 33 8099 N ot invited 1743 /8099 (21.5 % ) Invited 6356/8099 (78.5 % ) R efused participation 872/6356 (13.7 % ) A ccepted participation 5484/6356 (86.3 % ) E xcluded in pregnancy * 202 /5484 (3.7 % ) Baseline: Participants at term G estational w eek 37 5282/5484 (96.3 % ) Pregnancy questionnaire Pregnancy questionnaires not returned 336 /5282 (6.3 % ) Pregnancy questionnaires returned from participants at term 4946/5282 (93.6 % ) Excluded at delivery * 1115 /4946 (22.5 % ) E xcluded due to m issing civil registration num ber 138/4946 (2.6 % ) Follow -up: D elivery and post partum To follow -up Four data records and 3693/4946 (74.7 % ) postpartum questionnaire L ost to follow -up 323/3693 (8.7 % ) Incom plete sets of data records and post partum questionnaires† 560/3693 (15.1 % ) Sets of data records and questionnaires for analyses of Incidence , outcom es and risk indicators 2810/3693 (76.0 % ) *E xclusion criterea: < 37 or > 42 gestational w eeks, m ultiple pregnancy , breech presentation, elective cesarean delivery, induction and incorrect inclusion into the study †Incom plete sets of data records and post partum questionnaires usable for analyses in som e substudies of The D anish D ystocia Study Th Figure 1 e Danish Dystocia Study Flowchart The Danish Dystocia Study Flowchart. Page 3 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 Table 1: Definitions of Stages and Phases of Labour and Diagnostic Criteria for Dystocia Stage of labour Definition of stage and phase Diagnostic Criteria for Dystocia First stage From onset of regular contractions leading to cervical dilatation to full dilatation of cervix Latent phase Cervix 0 – 3.9 cm dilatation The diagnosis was not to be given in this phase Active phase Cervix ≥ 4 cm dilatation < 1/2 cm dilatation of cervix per hour, assessed over 4 hours = dystocia Second stage From full dilatation of cervix to the child is born Descending phase From full dilatation of cervix to strong > 2 hours without descent = dystocia. and irresistible urge to push If epidural is administered: > 3 hours = dystocia Expulsive phase Strong and irresistible pushing during the > 1 hour without progress = dystocia major part of the contraction The examined risk indicators of dystocia were: dilatation confidence intervals (CI). Adjustments were made for age and consistency of cervix, thickness of lower segment, in four groups (< 25, 25–29, 30–34, 35+), height in three descent of fetal head and fetal head-to-cervix contact at groups (< 160, 160–169, 170+), pre-pregnancy BMI in admission to the delivery ward, infertility prior to current five groups (< 18.5, 18.5–24.9, 25.0–29.9, 30+) and level pregnancy and use of epidural analgesia. Measurements of of physical activity in first trimester in four groups (regular lower uterine segment, cervix and fetal head conditions intensive physical training and competitive sports several were performed manually during routine vaginal exami- times/week, athletics or heavy physical activity ≥ 4 hours/ nations. In the pilot phase of the study two methods of week, light physical activity ≥ 4 hours/week, predomi- validation of vaginal examinations were considered: use nantly sedentary lifestyle) as these potential confounders of a model or an additional examination by a second mid- may be independent risk factors for dystocia, and some wife. Both methods were discarded as constituting an are known to interact with the risk factors under study, i.e. unacceptable extra workload and also, in the case of the BMI and birth weight and age and infertility. Age, height, latter, for ethical reasons. We assumed that the weight of pre-pregnancy BMI and level of physical activity were ini- the expected child plays a role in the progress of labour. tially all included in the model and subsequently deleted However, the actual weight of the expected child is one by one with replacement. None of the variables unknown and cannot with accuracy be taken into consid- changed the estimate by more than 10% but we decided eration for potential clinical management of the labour. to keep all variables in the model since they did not Our analyses included as well as excluded, respectively, increase the variance of the OR. We also estimated OR for birth weight in the regression model to examine the effect the clinical risk indicators with all variables included in of birth weight on the clinical risk indicators. the model to adjust for their mutual associations and to identify which factors had the strongest independent asso- Prior to analyses, dilatation of cervix and birth weight ciation. We calculated trend values for continuous varia- were categorized according to predefined categories. If bles (cervix dilatation and birth weight) by using logistic epidural analgesia was applied after dystocia was diag- regression. Odds ratio for trend represent a change in OR nosed and augmentation was initiated (n = 47), women per unit increase or decrease in the exposures under study. were excluded from the risk analyses. The categories of In order to take into consideration potential clinical and risk indicators are described in Table 2. social characteristics of the nine participating centres, we adjusted all analyses by including study centre in the Ethics model as a dummy variable. Descriptive statistics for con- Since no invasive procedures were applied in the study, no tinuous variables are presented as means with 95% CI or Ethics Committee System approval was required by Dan- medians (Inter-quartile range (IQR)) depending on distri- ish law. The policy of the Helsinki Declaration was fol- butional characteristics. lowed throughout the data collection and analyses. Written consent was obtained and person-specific data Statistical analyses were performed using SPSS 14.0 soft- were protected by codes. Permission to establish the data- ware (SPSS Inc., Chicago, Il). base was obtained from the Danish Data Protection Agency j. no. 2004-41-3995. Results The mean maternal age was 28.7 years (95% CI; 28.5 – Statistical methods 28.8) at entry into the cohort, but women with dystocia Binary logistic regression analyses were used to estimate were slightly older (29.1 yrs.). Median pre-pregnancy BMI crude and adjusted odds ratio (OR) for dystocia with 95% was 22.3 (IQR 4.2) with no significant difference between Page 4 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 Table 2: Odds Ratios for dystocia with 95% confidence intervals according to obstetric characteristics N 2810 Un-adjusted Adjusted OR* All variables All variables included Trend† OR OR (95% CI) included except birth weight (95% CI) Infertility treatment prior to current pregnancy No 2449 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Yes 184 1.13 0.95 (0.69–1.31) 0.92 (0.65–1.29) 1.09 (0.78–1.53) Missing 177 Dilatation of cervix at admission 0.83 (0.80–0.86) 0–3 cm 1086 1.67 1.63 (1.38–1.92) 1.29 (1.06–1.57) 1.21 (1.00–1.47) 4–10 cm 1575 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Missing 149 Consistency of cervix at admission Tense 585 1.25 1.31 (1.04–1.65) 1.0 (0.79–1.26) 0.98 (0.79–1.23) Soft 1794 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Missing 431 Thickness of lower segment at admission Thick 583 1.30 1.32 (1.09–1.61) 0.88 (0.69–1.12) 0.91 (0.72–1.14) Thin 1712 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Missing 515 Descent of fetal head at admission Above the inter-spinal-line 2367 2.33 2.29 (1.80–2.92) 1.80(1.32–2.45) 1.92 (1.42–2.58) At or under the inter-spinal-line 311 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Missing 132 Fetal head-to-cervix contact Good 1921 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Poor 159 1.88 1.83 (1.31–2.56) 1.62 (1.09–2.40) 1.57 (1.08–2.27) Cannot be assessed 455 Missing 275 Birth weight 1.001 (1.00–1.00) 2000–2499 gr 23 0.14 0.14 (0.32–0.60) 0.27 (0.61–1.21) 2500–2999 gr 282 0.57 0.51 (0.38–0.69) 0.55 (0.40–0.77) 3000–3499 gr 1040 0.78 0.74 (0.62–0.89) 0.76 (0.62–0.93) 3500–3999 gr 1016 1 (ref.) 1 (ref.) 1 (ref.) 4000–4499 gr 392 1.23 1.29 (1.02–1.65) 1.06 (0.83–1.41) ≥ 4500 gr 53 1.36 1.37 (0.78–2.41) 1.32 (0.70–2.46) Epidural analgesia No epidural 2284 1 (ref.) 1 (ref.) 1 (ref.) 1 (ref.) Epidural analgesia 316 5.49 5.65 (4.33–7.38) 4.65 (3.53–6.13) 4.77 (3.65–6.22) * Crude Odds Ratios controlled for age, height, pre-pregnancy BMI and physical activity, including a variable for the participating departments (9 levels). † Test for trend performed on continuous variables. First line: Regression coefficient for change in OR per unit increased, second line: 95% CI. the two groups. In this population 84% were non-smok- (part of the same manifestation) and when we included ers and 66% were engaged in light physical activity > 4 all variables from Table 2 in the statistical model, most hours per week. estimates were attenuated as expected. After mutual adjustments the estimates that remained strongest were Table 2 presents the unadjusted and adjusted OR within epidural analgesia, descent of fetal head above the inter- categories of obstetric risk indicators. Among the risk indi- spinal diameter, poor fetal head-to-cervix contact and dil- cators recorded at the woman's admission to the delivery atation of cervix < 4 cm at admission. ward, cervix dilatation < 4 cm, descent of fetal head above the inter-spinal level and poor fetal head-to-cervix contact Expecting a child with a birth weight < 3500 gr. appeared had the strongest association with dystocia. to be protective for dystocia while expecting a child with a birth weight > 4000 gr. was associated with increased risk Epidural analgesia was also strongly associated with dys- of dystocia compared to birth weights 3500–3999 gr. The tocia. The variables related to cervix are closely correlated last column presents OR without birth weight included in Page 5 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 the statistical model. Birth weight appeared to have a of epidural analgesia on the course of labour and delivery minor effect on OR and confidence intervals of the clinical and maternal and fetal outcomes [18,21-27]. Lower risk indicators. plasma oxytocin levels are found in women with epidural analgesia [40] and this may slow the progress of labour. Alehagen et al. found that women who received epidural Discussion The vaginal examinations at the woman's admission to analgesia had experienced more fear, but not more pain, the labour ward provided several prognostic indicators of before the administration of epidural analgesia than did dystocia later in labour. Expecting a child with a high birth women who did not receive epidural analgesia [41] and weight and the use of epidural analgesia were also associ- fear may prolong duration of labour [42]. Recent reviews ated with the risk of dystocia, the latter association being come to the conclusion that epidural analgesia appears to particularly strong. prolong labour's second stage and prompt more use of oxytocin [25-27]. Although we excluded from the analy- Fetal head above the inter-spinal diameter had the strong- ses those who were treated with epidural analgesia after est association with dystocia among the factors present at being diagnosed with dystocia, reverse causation is still a admission of women in labour, also in the analyses that possible explanation of the association we find. If a need excluded birth weight. Others have found that lack of for pain relief or fear of pain are among the clinical pre- descent of fetal head often leads to cesarean delivery for cursors of dystocia, epidural analgesia could be part of the dystocia [17,36]. Descent of fetal head is correlated to dil- mechanism leading to dystocia. atation of the cervix, and cervix dilatation < 4 cm at admis- sion was associated with an increased risk of dystocia. We were not able to replicate findings of an association Women admitted with little cervical dilatation may have between dystocia and infertility treatment prior to the cur- unbearably painful contractions. Anxiety may play a role rent pregnancy, perhaps because our statistical power to for early admission as well as concern for high maternal detect such an association is low. Others have demon- blood pressure, fetal heart rates or other clinical condi- strated a near doubling of the risk of failure to progress in tions. High risk of dystocia in women admitted in early treated women [18]. labour has also been found other studies [29,30,37,38], perhaps because early admission introduces risk of iatro- Our findings of an association between high birth weight gene-induced treatments [29,30]. We believe, however, (4000–4499 gr.) and dystocia corroborate findings from that quality control of our data prior to analyses ensured other studies even though the definition of 'high birth that the dystocia diagnosis was registered exclusively in weight' varies [19,20,22]. Although the birth weight can women who met the criteria. We therefore assume that only be estimated before the child is born, the clinical iatrogenic factors have not played a major role in our find- implication of our findings could be that increased risk of ings. dystocia should be considered when an estimated birth weight is more than 4000 gr. A poor fetal head-to-cervix contact at admission was asso- ciated with near doubling of the odds of dystocia. Gough Our findings of association between the clinical condi- et al. found that low head-to-cervix force was associated tions dilatation of cervix, descent of fetal head and fetal with poor progress and delivery by cesarean section for head-to-cervix contact and dystocia may have significant dystocia [39]. Allman et al. examined the head-to-cervix clinical implications. Women admitted to hospital for force electronically and advocate that head-to-cervix force delivery have a vaginal examination upon admittance and is a better predictor of the likely rate of cervical dilatation information from this examination provides the clinical than intrauterine pressure and also a better predictor of basis for the primary management of labour. Weight of mode of delivery than the dilatation rate itself [15,16]. the child appears to have only minor effect on the OR Our findings based on manual assessments during vaginal related to the clinical conditions. examinations support Allman's findings of an association between poor head-to-cervix contact and dystocia. Strengths and limitations The study has limitations. We reached 78.5% of the Epidural analgesia had the strongest association with dys- women eligible for inclusion in the study and of these tocia among the risk indicators assessed. In total 71.2% of 86.3% accepted the invitation to participate. Missed inclu- women who were treated with epidural analgesia were sions were mainly a problem during the first months of diagnosed with dystocia. A similarly strong association data collection and we have no reason to believe that this between dystocia and epidural analgesia was reported led to over-sampling of women with low or high risk of from a population-based study of 106,755 deliveries dystocia as inclusion took place 6–8 weeks before deliv- without induction and with durations of delivery < 12 ery. Almost nine percent were lost to follow up, possibly hours [14], but the literature is inconsistent on the effects related to the extra work required from the participating Page 6 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 departments. The aims of the Danish Dystocia Study were commented on. All authors approved the final manu- descriptive as well as analytical and the data collection script. instruments comprised four detailed data records to be filled in by the obstetric staff during the woman's stay at Acknowledgements Christina Vestergaard is thanked for assistance in processing data and Steen the delivery ward. It may be that the mere burden of work Rasmussen for data extraction from the Danish Medical Birth Register. gave rise to some non-responses to items or non-comple- tion of entire data records. However, we have no reason to References assume that non-responses were directly related to risk of 1. American College of Obstetrics and Gynecology. ACOG Practice dystocia. Bulletin Number 49, December 2003: Dystocia and augmenta- tion of labor. Obstet Gynecol 2003, 102:1445-1454. 2. Gifford DS, Morton SC, Fiske M, Keesey J, Keeler E, Kahn KL: Lack We did not include an independent criterion for dystocia of progress in labor as a reason for cesarean. Obstet Gynecol based on descent of the fetal head and cases with a quick 2000, 95:589-595. 3. Foley ME, Alarab M, Daly L, Keane D, Rath A, O'Herlihy C: The con- descent but a slow dilatation may have been classified as tinuing effectiveness of active management of first labor, dystocia. We recommend that future studies make it pos- despite a doubling in overall nulliparous cesarean delivery. sible to identify this group. Evaluation of cervical condi- Am J Obstet Gynecol 2004, 191:891-895. 4. Sosa CG, Balaguer E, Alonso JG, Panizza R, Laborde A, Berrondo C: tions and descent of fetal head is difficult and subject to Meperidine for dystocia during the first stage of labor. A ran- considerable intra- and inter observer variation. We rec- domized controlled trial. Am J Obstet Gynecol 2004, 191:1212-1218. ommend that further studies include different methods of 5. Cluett ER, Pickering RM, Getliffe K, St George Saunders NJ: Ran- measuring conditions related to the cervix and the fetal domised controlled trial of labouring in water compared head (i.e. electronic monitoring). with standard of augmentation for management of dystocia in first stage of labour. BMJ 328(7435):314. 2004 Feb 7; Epub 2004 Jan 26 The study also has important strengths. The population 6. Treacy A, Robson M, O'Herlihy C: Dystocia increases with based cohort design, based upon primary and prospec- advancing maternal age. Am J Obstet Gynecol 2006, 195:760-763. 7. Friedman E: Labor, clinical evaluation and management 2nd edition. New tively collected data, is a strength. The risk of differential York: Appleton-Century-Crofts; 1978. misclassification was reduced as we used prospectively 8. Vahratian A, Troendle JF, Siega-Riz AM, Zhang J: Methodological challenges in studying labour progression in contemporary collected data on cervix and fetal head conditions and the practice. Paediatr Perinat Epidemiol 2006, 20:72-78. study was based on strict diagnostic criteria agreed upon 9. Greenberg MB, Cheng YW, Hopkins LM, Stotland NE, Bryant AS, by all. Central as well as local supervisors took part in all Caughey AB: Are there ethnic differences in the length of labor? Am J Obstet Gynecol 2006, 195:743-748. phases of the data collection. 10. Zhu BP, Grigorescu V, Le T, Lin M, Copeland G, Barone M: Labor dystocia and its association with interpregnancy interval. Am J Obstet Gynecol 2006, 195:121-128. Conclusion 11. Turcot L, Marcoux S, Fraser WD: Multivariate analysis of risk Our study contributes further evidence of an increased factors for operative delivery in nulliparous women. Cana- risk of dystocia in nulliparous women who, at admission dian Early Amniotomy Study Group. Am J Obstet Gynecol 1997, 176:395-402. to hospital, present with a descent of fetal head above the 12. Danish Medical Birth Register [http://www.sst.dk] inter-spinal diameter and a cervix dilatation < 4 cm. We 13. Blix E, Pettersen SH, Eriksen H, Royset B, Pedersen EH, Oian P: [Use found that a tense cervix, a thick lower segment and a of oxytocin augmentation after spontaneous onset of labor]. Tidsskr Nor Laegeforen 2002, 122:1359-1362. poor contact between the fetal head and the cervix are risk 14. Oscarsson ME, Ahmer-Wåhlin I, Rydhstroem H, Kallen K: Outcome indicators for dystocia. Further studies should examine if in obstetric care related to oxytocin use. A population-based study. Acta Obstet Gynecol Scand 2006, 85:1094-1098. fetal head-to-cervix contact is a significant predictor of 15. Allman AC, Genevier ES, Johnson MR, Steer PJ: Head-to-cervix dystocia and if differentiation of the management of dys- force: an important physiological variable in labour. 2. Peak tocia can be based on assessment of fetal head-to-cervix active force, peak active pressure and mode of delivery. Br J Obstet Gynaecol 1996, 103:769-775. contact. The observed association between epidural anal- 16. Allman AC, Genevier ES, Johnson MR, Steer PJ: Head-to-cervix gesia and increased risk of dystocia is of interest and may force: an important physiological variable in labour. 1. The have a causal explanation. temporal relation between head-to-cervix force and intrau- terine pressure during labour. Br J Obstet Gynaecol 1996, 103:763-768. Competing interests 17. Roshanfekr D, Blakemore KJ, Lee J, Hueppchen NA, Witter FR: Sta- tion at onset of active labor in nulliparous patients and risk The authors declare that they have no competing interests. of cesarean delivery. Obstet Gynecol 1999, 93:329-331. 18. Sheiner E, Levy A, Feinstein U, Hallak M, Mazor M: Risk factors and Authors' contributions outcome of failure to progress during the first stage of labor: a population-based study. Acta Obstet Gynecol Scand 2002, HK and AKD planned the study. HK carried out the data 81:222-226. collection. Analyses were planned by HK, JO and PN. PN 19. Sheiner E, Levy A, Feinstein U, Hershkovitz R, Hallak M, Mazor M: conducted the data validation. HK conducted the analy- Obstetric risk factors for failure to progress in the first ver- sus the second stage of labor. J Matern Fetal Neonatal Med 2002, ses. HK, BO, AKD and JO interpreted the results. HK wrote 11:409-413. the drafts of the manuscript, which the other authors 20. Mocanu EV, Greene RA, Byrne BM, Turner MJ: Obstetric and neo- natal outcome of babies weighing more than 4.5 kg: an anal- ysis by parity. Eur J Obstet Gynecol Reprod Biol 2000, 92:229-233. Page 7 of 8 (page number not for citation purposes) BMC Pregnancy and Childbirth 2008, 8:45 http://www.biomedcentral.com/1471-2393/8/45 21. Feinstein U, Sheiner E, Levy A, Hallak M, Mazor M: Risk factors for http://www.biomedcentral.com/1471-2393/8/45/prepub arrest of descent during the second stage of labor. Int J Gynae- col Obstet 2002, 77:7-14. 22. Schiessl B, Janni W, Jundt K, Rammel G, Peschers U, Kainer F: Obstetrical parameters influencing the duration of the sec- ond stage of labor. Eur J Obstet Gynecol Reprod Biol 2005, 118:17-20. 23. Fraser WD, Cayer M, Soeder BM, Turcot L, Marcoux S: Risk factors for difficult delivery in nulliparas with epidural analgesia in second stage of labor. Obstet Gynecol 2002, 99:409-418. 24. Zhang J, Yancey MK, Klebanoff MA, Schwarz J, Schweitzer D: Does epidural analgesia prolong labor and increase risk of cesar- ean delivery? A natural experiment. Am J Obstet Gynecol 2001, 185:128-134. 25. Anim-Somuah M, Smyth R, Howell C: Epidural versus non-epi- dural or no analgesia in labour. Cochrane Database Syst Rev 2005:CD000331. 26. Leighton BL, Halpern SH: The effects of epidural analgesia on labor, maternal, and neonatal outcomes: a systematic review. Am J Obstet Gynecol 2002, 186:S69-S77. 27. Lieberman E, O'donoghue C: Unintended effects of epidural analgesia during labor: a systematic review. Am J Obstet Gynecol 2002, 186:S31-S68. 28. Tanbo T, Dale PO, Lunde O, Moe N, Abyholm T: Obstetric out- come in singleton pregnancies after assisted reproduction. Obstet Gynecol 1995, 86:188-192. 29. Bailit JL, Dierker L, Blanchard MH, Mercer BM: Outcomes of women presenting in active versus latent phase of spontane- ous labor. Obstet Gynecol 2005, 105:77-79. 30. Rahnama P, Ziaei S, Faghihzadeh S: Impact of early admission in labor on method of delivery. Int J Gynaecol Obstet 2006, 92:217-220. 31. Johanson R, Newburn M, Macfarlane A: Has the medicalisation of childbirth gone too far? BMJ 2002, 324:892-895. 32. Bell JS, Campbell DM, Graham WJ, Penney GC, Ryan M, Hall MH: Can obstetric complications explain the high levels of obstet- ric interventions and maternity service use among older women? A retrospective analysis of routinely collected data. BJOG 2001, 108:910-918. 33. Kjærgaard H: Dystocia in nulliparous women. Incidence, out- comes, risk indicators and women's experiences. In PhD thesis Lund University, Department of Health Sciences, Faculty of medicine, Sweden; 2007. 34. Danish Society of Obstetrics and Gynecology [http:// www.dsog.dk] 35. Coding guidelines of obstetric interventions in Denmark [http://www.dsog.dk/files/Obstetriske_koder_10112005.pdf] 36. Falzone S, Chauhan SP, Mobley JA, Berg TG, Sherline DM, Devoe LD: Unengaged vertex in nulliparous women in active labor. A risk factor for cesarean delivery. J Reprod Med 1998, 43:676-680. 37. Holmes P, Oppenheimer LW, Wen SW: The relationship between cervical dilatation at initial presentation in labour and subsequent intervention. BJOG 2001, 108:1120-1124. 38. McNiven PS, Williams JI, Hodnett E, Kaufman K, Hannah ME: An early labor assessment program: a randomized, controlled trial. Birth 1998, 25:5-10. 39. Gough GW, Randall NJ, Genevier ES, Sutherland IA, Steer PJ: Head- to-cervix forces and their relationship to the outcome of labor. Obstet Gynecol 1990, 75:613-618. 40. Rahm VA, Hallgren A, Hogberg H, Hurtig I, Odlind V: Plasma oxy- tocin levels in women during labor with or without epidural Publish with Bio Med Central and every analgesia: a prospective study. Acta Obstet Gynecol Scand 2002, scientist can read your work free of charge 81:1033-1039. 41. Alehagen S, Wijma B, Lundberg U, Wijma K: Fear, pain and stress "BioMed Central will be the most significant development for hormones during childbirth. Journal of Psychosomatic Obstetrics disseminating the results of biomedical researc h in our lifetime." and Gynecology 2005, 26:153-165. Sir Paul Nurse, Cancer Research UK 42. Lederman RP, Lederman E: The relationship of maternal anxi- ety, plasma catecholamines and plasma cortisol to progress Your research papers will be: in labor. Am J Obstet Gynecol 1978, 132:495-500. available free of charge to the entire biomedical community peer reviewed and published immediately upon acceptance Pre-publication history cited in PubMed and archived on PubMed Central The pre-publication history for this paper can be accessed yours — you keep the copyright here: BioMedcentral Submit your manuscript here: http://www.biomedcentral.com/info/publishing_adv.asp Page 8 of 8 (page number not for citation purposes)

Journal

BMC Pregnancy and ChildbirthSpringer Journals

Published: Oct 6, 2008

There are no references for this article.