Do risk factors for elective cesarean section differ from those of cesarean section during labor in low risk pregnancies?

Aims: As the rate of cesarean sections has continuously increased over the last three decades, we sought to identify the factors related to elective cesarean section (ECS) and cesarean section during labor (LCS) in low risk pregnancies and to determine if they differ for the two types of cesarean. Methods: We conducted an observational study that included all maternity units in metropolitan France. Using the sample from the National Perinatal Survey 2003, we included 5393 women who met the criteria of a low risk pregnancy. The odds ratios (OR) corresponding to ECS and LCS were calculated for various characteristics for the women, fetus and maternity units, using a multinomial logistic regression model. For each factor, the adjusted OR corresponding to ECS and LCS were compared using the Wald's test. Results: The rates of ECS and LCS in our population were 2.9% and 4.3%, respectively. Maternal age >= 30 years, body mass index >= 25 kg/m(2), primiparity and nationality from an African country were associated with an increased risk for both ECS and LCS. Those maternity units registering a low volume of deliveries (< 1000/year) and those with a high rate of cesarean section during the previous year had an increased rate of LCS. Conclusion: Women with low risk pregnancies at term may present several factors that appear to create an "environment'' favorable for cesarean section, leading to an increase in the likelihood of both ECS and LCS. Furthermore, several characteristics concerning maternity units are associated with an increased likelihood of LCS. Understanding the impact of various factors on the decision about the mode of delivery is essential for obstetrical teams concerned with controlling the progressive increase in the rate of cesarean sections.