Identifying the Effect of Cesarean Delivery on Maternal Postpartum Weight and Subsequent Fertility

Cesarean delivery accounts for nearly one-third of all births in the U.S. and contributes to an estimated $38 billion in healthcare costs each year.  Although Cesarean delivery has a long record of improving maternal and neonatal mortality and morbidity, increased utilization over time has yielded public health concerns and calls for reductions. Studies have linked Cesarean delivery to increased maternal postpartum weight and decreased subsequent fertility, which have significant implications for the obesity epidemic and population-level fertility rates.  Previous literature, however, typically does not address selection biases stemming from correlations between pre-pregnancy weight and health and Cesarean delivery.  In this study, we rely on fetal malpresentation as a plausibly exogenous factor that warrants Cesarean delivery but is uncorrelated with pre-pregnancy weight or health. We use a unique dataset of hospital administrative records (including vital records fields) from multiple hospitals in the state of WI from 2006 to 2013, and we are able to link subsequent birth to the same mother. In comparing  mothers who deliver via Cesarean due to fetal malpresentation to mothers who deliver vaginally, we find no differences in any of the pre-delivery characteristics. When we examine post-delivery outcomes, we find that Cesarean mothers weigh about ¾ of a pound less at the start of their second pregnancy relative to their vaginal delivery counterparts, and their subsequent fertility is slightly diminished, but only at the margin for having 2 or more subsequent births. Overall, our findings provided limited support for the negative impact of Cesarean delivery on weight retention or fertility.