The effect of maternal health conditions on maternal morbidity in women with a prior cesarean: the role of elective repeat cesarean delivery

Background: We evaluated women with a prior cesarean delivery (CD) who were eligible for elective repeat CD or trial of labor to test whether the risk of severe maternal morbidity (SMM) was: 1) directly associated with important pre-existing and gestational conditions or 2) indirectly associated (significantly increased or decreased) with the decision to undergo elective repeat CD.Methods: Women with a prior CD who had inborn, liveborn, term, singleton, vertex deliveries were identified in California 2010-2011 hospital discharge datasets. Using discharge codes, this population was stratified into two groups: attempted labor and elective repeat CD. A mediation model (stratified by younger vs. older women [>35 years]) was built for each of the following maternal conditions (exposure): chronic/gestational diabetes mellitus (DM), chronic/gestational hypertension, heart disease, obesity, and mental health diagnoses. Elective repeat CD was the mediator and SMM was the outcome.Results: Of 141,535 eligible deliveries, 72.7% had an elective repeat CD; 2.3% had SMM, which occurred in 2.2% of younger vs. 2.6% of older women. For younger and older women respectively, the modeled total effect odds ratios (95% CI) for heart disease were: 10.7 (8.5, 13.5) and 8.8 (6.4, 12.2); for hypertension: 1.7 (1.4, 1.9) and 2.0 (1.6, 2.4); and for mental health diagnoses: 1.9 (1.6, 2.3) and 1.7 (1.3, 2.3). Neither DM nor obesity demonstrated a direct effect. Odds ratios for indirect effects were negligible for all models.Conclusion: Among women with a prior CD, in the presence of important health conditions, the increased risk of SMM mediated by an elective repeat CD was negligible.