Changes in diabetes status between pregnancies and impact on subsequent newborn outcomes

Pregnancies complicated by gestational diabetes mellitus (GDM) or preexisting diabetes mellitus (DM) are at high risk for adverse newborn outcomes. Whether GDM history, recurrence, or transition to DM modifies such risks is unknown.

Medical record data on 62,013 repeat singleton pregnancies were collected retrospectively from women who delivered at least twice in Utah (2002 through 2010). Poisson regression models with robust variance estimators were used to estimate relative risks (RR) and 95% confidence intervals (CI) associated with GDM/DM status at the previous and/or current pregnancy relative to those without GDM/DM at either. Large for gestational age (LGA), shoulder dystocia, preterm birth (<37 weeks), respiratory distress syndrome, and other neonatal morbidities were examined adjusting for study site, maternal age, race, parity, interpregnancy interval, prepregnancy body mass index, and smoking status.

GDM in the previous pregnancy alone increased the risk of LGA in the current pregnancy (RR, 1.20; 95% CI, 1.05-1.38). Recurrent GDM increased the risks of LGA (RR, 1.76; 95% CI, 1.56-1.98), shoulder dystocia (RR, 1.98; 95% CI, 1.46-2.70), and preterm birth (RR, 1.68; 95% CI, 1.44-1.96) beyond that observed for pregnancies with current GDM alone. Women with GDM in a previous pregnancy that transitioned to DM in the current pregnancy and women with DM prior to the previous pregnancy had increased risks of all above outcomes.

GDM in a previous pregnancy alone without recurrence may still confer an increased LGA risk. Pregnancies complicated by GDM that transition to DM and those with DM prior to the previous pregnancy have the highest risks of adverse newborn outcomes.