Estimation of an expected caesarean section rate taking into account the case mix of a maternity hospital. Analysis from the AUDIPOG Sentinelle Network (France). Obstetricians of AUDIPOG. Association of Users of Computerised Files in Perinatalogy, Obstetrics and Gynaecology

Abstract

Objective: To provide maternity unit with an expected caesarean section rate, according to its case mix (i.e. women's characteristics associated with caesarean section risk).

Design: Cohort study.

Setting: 149 maternity units in France.

Sample: 40,512 single births collected by the French Sentinelle Network, in January every year, from 1994 until 1998.

Methods: Univariate analysis was used to identify caesarean section risk factors, and multivariate analysis to adjust for the role of the maternity units' characteristics, after taking into account the women's characteristics. A two-level logistic model was used to show that the caesarean section rate varied according to maternity units' characteristics and to estimate therefore expected caesarean section rates (before and during labour), for each maternity unit, according to its case mix.

Main outcome: Caesarean section rates (before and during labour).

Results: Within the Sentinelle Network the caesarean section rate was 15.0% (7.6% were before labour). The joint effect of the size and juridical status on caesarean section risk was studied. The reference hospital was university maternity units with more than 2000 deliveries/year. Community or private maternity units with more than 2000 deliveries/year carried out fewer prophylactic caesarean sections than the reference hospital (ORadj = 0.7 and 0.6, respectively). Conversely, private maternity units with fewer than 2000 deliveries/year performed more prophylactic caesarean sections than the reference hospital (ORadj = 1.7). The two-level logistic model showed that a maternity unit effect still existed after taking into consideration both women's characteristics and those of the maternity unit, and estimated expected caesarean section rates.

Conclusion: Knowledge of the expected caesarean section rate constitutes a personal reference to which the maternity hospital can compare its observed caesarean section rate, and is thus likely to have a significant effect on delivery practices.