Impact of previous gestational diabetes management on perinatal outcomes in subsequent pregnancies affected by gestational diabetes mellitus

OBJECTIVE: To determine the impact of prior gestational diabetes mellitus (GDM) on perinatal outcomes in a subsequent GDM pregnancy. METHODS: This retrospective cohort study included 544 multiparous patients with two consecutive pregnancies between 2012-2019, where the second (index) pregnancy was affected by GDM. The primary exposure was prior GDM diagnosis, categorized into medical and dietary management. The primary outcome was a composite including need for pharmacotherapy, large-for-gestational age, or neonatal hypoglycemia. Adjusted odds ratios (aOR) were calculated using multivariable logistic regression controlling for maternal age, pre-pregnancy body mass index, and gestational age at GDM diagnosis in the index pregnancy. RESULTS: Of the 544 patients, 164 (30.1%) had prior GDM. Prior GDM significantly increased the likelihood of composite outcome compared to no prior GDM (74.4% vs. 57.4%; P < 0.001). After adjusting for confounders, prior GDM remained significantly associated with the composite outcome (aOR 2.03, 95% confidence interval [CI] 1.31-3.15). Stratifying by prior GDM treatment modality, a significant association was found for prior pharmacotherapy-controlled GDM (aOR 3.29, 95% CI 1.64-6.59), but not for prior diet-controlled GDM (aOR = 1.54, 95% CI 0.92-2.60). CONCLUSION: A history of pharmacotherapy-controlled GDM in a previous pregnancy increases odds of adverse perinatal outcomes in a subsequent GDM pregnancy.