The relationship between cesarean section rate in term singleton pregnancies, maternal weight, and weight gain during pregnancy.

Objective: Pregravid maternal weight and appropriate weight gain during pregnancy might be associated with increased cesarean section rate.

Study Design: We used data from the Slovenian National Perinatal Information System to select singleton pregnancies born at ≥38 weeks, during the period between 2003 and 2012. We calculated the frequencies of urgent and elective cesarean sections (UCS and ECS, respectively) in mothers who gained less than, more than, and as recommended by the Institute of Medicine (IOM) according to their pregravid body mass index (BMI).

Results: The analysis included 170,121 women who delivered singletons ≥38 weeks. A total of 24,327 (14.3%) women underwent cesarean section: 14,692 (8.6%) UCS and 9635 (5.7%) ECS. The frequency of cesareans, both UCS and ECS, increases as BMI increases irrespective of weight gain pattern. The frequency of urgent cesareans in all women increases and that of elective cesareans among obese women decreases as the level of weight gain increases from undergainers to overgainers.

Conclusion: The combination of pregravid BMI and weight gain pattern is an important determinant of cesarean section rates at term.