Abstract / Summary
Objective: To explore the associations of maternal overweight/obesity and pre-pregnancy body mass index (BMI) on glycemia and pregnancy outcomes in women with pregestational type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM).
Research design and methods: We examined prospectively collected data (2010-2019) involving 264 singleton pregnancies affected by pregestational T1DM or T2DM. On separate analyses within each diabetes subtype, pregnancy outcomes were compared across maternal BMI categories and using BMI as a continuous variable. Co-primary outcomes included preterm delivery, large-for-gestational age (LGA) infants, and pre-eclampsia.
Results: In those with T1DM (N = 124, 46% overweight or obese), we did not find an association between increasing BMI category and greater risks of pre-eclampsia, preterm delivery, or LGA infants. However, amongst the women with T1DM, overweight and obesity were associated with higher odds of exceeding the first trimester HbA1c target (6.5%), and each 1 kg/m2 increase in BMI was associated with higher odds of excess GWG as well as caesarean delivery. In the T2DM cohort (N = 140, 90% overweight or obese), each 1 kg/m2 increase in BMI above ethnicity-adjusted normal range was associated with increased odds of pre-eclampsia (aOR 1.082, 95% CI 1.024 to 1.144) and preterm delivery (aOR 1.042, 95% CI 1.001 to 1.084). In the T2DM cohort, the odds of LGA were numerically higher with each 1 kg/m2 increase in BMI, but this was no longer statistically significant after adjustment for potential confounders.
Conclusions: On separate analyses within each diabetes subtype, maternal overweight/obesity was potentially associated with increased odds of pre-eclampsia and preterm delivery in the T2DM cohort. Amongst those with T1DM, maternal overweight/obesity was associated with non-attainment of first trimester HbA1c targets. Regression analyses were performed in an exploratory and hypothesis-generating manner, and larger-scale studies are required to directly compare the effects of maternal overweight/obesity on pregnancy outcomes in T1DM vs T2DM.