Prepregnancy, gestational diabetes linked to congenital birth defects

Having a diabetes prior to pregnancy and, to a lesser extent, gestational diabetes mellitus (GDM) contribute to an increased risk of several subtypes of congenital anomalies in newborns, as reported in a study.

The analysis involved 29,211,974 live births to mothers aged 18–49 years. Of the mothers, 242,600 had prepregnancy diabetes and 1,685,479 had GDM. Compared with mothers who had no diabetes before and during pregnancy, those with prepregnancy diabetes and GDM were more likely to be older, less educated, have higher parities and prepregnancy hypertension, and be overweight or obese.

Among infants, 90,061 had congenital anomalies at birth. These conditions were more common among infants born to mothers who had prepregnancy diabetes or GDM than among those whose mothers had no diabetes.

Multivariable regression analysis confirmed the association between maternal diabetes and congenital anomalies, with adjusted risk ratios (RRs) of 2.44 (95 percent confidence interval [CI], 2.33–2.55) in prepregnancy diabetes and 1.28 (95 percent CI, 1.24–1.31) in GDM. The estimates were generally consistent across subgroups defined by maternal age, race/ethnicity, prepregnancy obesity status, and infant sex.

With regard to subtypes of congenital anomalies, maternal prepregnancy diabetes and GDM were associated with an increased risk of most subtypes, including cyanotic congenital heart disease (RR, 4.61, 95 percent CI, 4.28–4.96 and RR, 1.50, 95 percent CI, 1.43–1.58, respectively) and hypospadias (RR, 1.88, 95 percent CI, 1.67–2.12 and RR, 1.29, 95 percent CI, 1.21–1.36, respectively).

The findings further clarify the potential effects of maternal diabetes on congenital anomalies. As such, preconception counseling in women with pre-existing diabetes or at risk of GDM may be beneficial in the prevention of congenital anomalies.