Delivery timing and cesarean delivery risk in women with mild gestational diabetes mellitus

Objective The purpose of this study was to evaluate the relationship between gestational age (GA) and induction of labor (IOL) and the rate of cesarean delivery in women with mild gestational diabetes mellitus. Study Design We conducted a secondary analysis of data from a multicenter randomized controlled trial of mild gestational diabetes mellitus treatment. Cesarean delivery rate of women delivering at term (≥37 weeks' gestation) was evaluated by 2 complementary approaches: (1) IOL vs spontaneous labor: women who were induced at each GA compared with those who spontaneously labored at the same GA and (2) IOL vs expectant management: women who delivered after IOL at each GA compared with those who delivered after spontaneous labor at the same GA or subsequently after spontaneous or induced labor (outcome at each week compared with expectant management at that week). Logistic regression adjusted for potential confounders. Results The overall cesarean delivery rate was 13%. When compared with 39 weeks' gestation (either IOL or spontaneous labor) as the referent, there was no significant difference in the cesarean delivery rate in women who delivered at 37, 38, or 40 weeks' gestation. However, IOL was associated with a 3-fold increase in cesarean delivery rate at 41 weeks' gestation and beyond, as compared with IOL at 39 weeks' gestation. Similarly, there was a 3-fold increase in the cesarean delivery rate in women who were induced when compared with those who were treated expectantly at 40 completed weeks' gestation. Conclusion Induction of labor in women with mild gestational diabetes mellitus does not increase the rate of cesarean delivery at <40 weeks' gestation.