Is gestational age at term a risk factor for ongoing pregnancies in nulliparous women: A prospective cohort study.

BACKGROUND: The results of American observational studies and 1 large, randomized trial show that elective induction of labor among nulliparous women can reduce cesarean delivery rates and suggest that gestational age at delivery may be a risk factor for cesarean delivery in pregnancies managed expectantly. However, data on the risk of cesarean delivery at term in ongoing pregnancies are sparse, especially in high-income countries, and further information is needed to explore the external validity of these previous studies. OBJECTIVE: This study aimed to evaluate the risk of cesarean delivery for each gestational week of ongoing pregnancy in nulliparous women with a singleton fetus in the cephalic presentation at term in a French population. STUDY DESIGN: This retrospective study was conducted in a perinatal network of 10 maternity units from January 1, 2016, to December 31, 2017, and included all nulliparous women with a singleton fetus in the cephalic presentation who gave birth at term (≥37 0/7 weeks of gestation). From the start of term (37 completed weeks) and at the start of each subsequent week of completed gestation (each week + 0 days), ongoing pregnancy was defined as that of a woman who was still pregnant and who gave birth at any time after that date. For each week of gestation for these ongoing pregnancies, the cesarean delivery rate was defined as the number of cesarean deliveries performed in each ongoing pregnancy group divided by the number of women in this group. Separate models for each week of gestation, adjusted by maternal characteristics and hospital status, were used to compare the cesarean delivery risk between ongoing pregnancies and those delivered the preceding week. The same methods were applied to subgroups defined according to the mode of labor onset. Odds ratios were calculated after adjusting for maternal age and educational level, presence of severe preeclampsia, and maternity unit status. RESULTS: The study included 11,308 nulliparous women, 2544 (22.5%) of whom had a cesarean delivery. These rates remained stable for ongoing pregnancies at 37 0/7, 38 0/7, and 39 0/7 weeks of gestation; the rates were 22.5% (95% confidence interval, 21.7-23.2), 22.6% (95% confidence interval, 21.8-23.3); and 22.7% (95% confidence interval, 21.9-23.6), respectively. The risk of cesarean delivery started to increase in ongoing pregnancies at 40 0/7 weeks of gestation (24.3%; 95% confidence interval, 23.1-25.4) and especially at 41 0/7 weeks of gestation (30.7%; 95% confidence interval, 28.9-32.5). Similar trends were also shown for all modes of labor onset and in every maternity unit. In univariate and multivariate analyses, ongoing pregnancy at or beyond 40 0/7 weeks of gestation was associated with a higher risk of cesarean delivery than pregnancy delivered the previous week: 24.3% of ongoing pregnancies at 40 0/7 weeks of gestation vs 19.9% of deliveries between 39 0/7 weeks of gestation and 39 6/7 weeks of gestation. The odds ratios were 1.28 (95% confidence interval, 1.15-1.44) or 30.4% of ongoing pregnancies at 41 0/7 weeks of gestation vs 1.73 (95% confidence interval, 1.51-1.96) or 19.6% of deliveries between 40 0/7 weeks of gestation and 40 6/7 weeks of gestation. CONCLUSION: Cesarean delivery rates increased starting at 40 0/7 weeks of gestation in ongoing pregnancies regardless of the mode of labor onset.

Cesarean section rate changes after audit and feedback with the Ten Group Classification System in a French perinatal network: A retrospective pre-post study.

INTRODUCTION: The rise in the number of cesarean sections (CS) is a major health public problem which concerns nearly all countries. It is suggested that the Ten Group Classification System be adapted to a procedure of audit/feedback cycles, which could have an effect on CS practice. Therefore, we aimed to study changes in CS rates between maternity wards in a perinatal network after implementation of the Ten Group Classification System in an audit with feedback. MATERIAL AND METHODS: This was a retrospective pre-post study of all births from 1 January 2012 to 31 December 2018, in a French perinatal network of 10 maternity wards in the Yvelines district of France. All live births occurring at a gestational age ≥24 weeks in the network were included. During the pre-period (1 January 2012 to 31 December 2014), the audit and feedback provided only overall CS rates. During the post-period (1 January 2015 to 31 December 2018), CS rates for each Robson Ten Group Classification System group were provided. Regression models, adjusted for maternal characteristics and maternity ward, were used to compare CS rates globally and for each group of the system. Variability of CS rates between maternity wards was analyzed using the coefficients of variation. RESULTS: There were 51 082 women who delivered during the pre-period and 63 964 during the post-period. The overall CS rate did not decrease (24.5% during the pre-period vs 25.1% during the post-period). There were no significant differences in CS rates for any group of the Ten Group Classification System after adjustment for maternity, maternal age and sociodemographic characteristics, nor did audit implementation decrease CS rate variability between maternity wards or within groups of the system. CONCLUSIONS: Implementation of an audit-and-feedback cycle using the Ten Group Classification System did not decrease either CS rates or variability between maternity wards.

Variation between hospital caesarean delivery rates when Robson's classification is considered: An observational study from a French perinatal network.

INTRODUCTION: WHO has recommended using Robson's Ten Group Classification System (TGCS) to monitor and analyze CD rates. Its failure to take some maternal and organizational factors into account, however, could limit the interpretation of CD rate comparisons, because it may contribute to variations in hospital CD rates. OBJECTIVE: To study the contribution of maternal socioeconomic and clinical characteristics and hospital organizational factors to the variation in CD rates when using Robson's ten-group classification system for CD rate comparisons. METHODS: This prospective, observational, population-based study included all deliveries at a gestational age > 24 weeks at the 10 hospitals of the French MYPA perinatal network in the Paris area. CD rates were calculated for each TGCS group in each hospital. Interhospital variations in these rates were investigated with hierarchical logistic regression models to quantify the variation explained by differences in patient and hospital characteristics when the TGCS is considered. Variations in CD rates between hospitals were estimated with median odds ratios (MOR) to express interhospital variance on the standard odds ratio scale. The percentage of variation explained by TGCS and maternal and hospital characteristics was also calculated. RESULTS: The global CD rate was 24.0% (interhospital range: 17-32%). CD rates within each TGCS group differed significantly between hospitals (P<0.001). CD was significantly associated with maternal age (>40 years), severe preeclampsia, and two organizational factors: hospital status (private maternities) and the deliveries per staff member per 24 hours. The MOR in the empty model was 1.27 and did not change after taking the TGCS into account. Adding maternal characteristics and hospital organizational factors lowered the MOR to 1.14 and reduced the variation between hospital CD rates by 70%. CONCLUSION: Maternal characteristics and hospital factors are needed to address variation in CD rates among the TGCS groups. Therefore, comparisons of these rates that do not consider these factors should be interpreted carefully.