Previous cesarean section, gestational age at first delivery and subsequent risk of pre-eclampsia in obese mothers

We examine the association between prior C-section and subsequent pre-eclampsia; and describe the effect of gestational age at prior C-section, and obesity status on this association.

The study population included women with two subsequent singleton births in Missouri between 1998 and 2005. The risk for pre-eclampsia/eclampsia was assessed among women with and without prior cesarean delivery. The two groups were followed to their second pregnancy and the occurrence of pre-eclampsia was documented. Additionally, the history of pre-eclampsia, prior cesarean at preterm, and obesity status were examined for their differential effects on the risk of pre-eclamsia.

Women with prior C-section were 28% more likely to have pre-eclampsia in their subsequent pregnancy [OR = 1.28; 95% CI = 1.20-1.37]. However, this result was not significant when women with pre-eclampsia in their first pregnancy were excluded. After this exclusion, a more than threefold increased risk for subsequent pre-eclampsia was observed in women with prior early C-section [OR = 3.15; 95% CI= 2.43-4.08], while the level of risk did not change in the prior late C-section group [OR = 0.90; 95% CI= 0.82-1.00]. Subgroup analysis suggested that obesity status modified the risk of prior early C-section but did not affect the risk for prior late C-section.

Preterm C-section in the first pregnancy may be associated with subsequent pre-eclampsia regardless of prior pre-eclampsia status.