Periconception glycemic control and congenital anomalies in women with pregestational diabetes

Introduction: To assess the relationship between periconception glycemic control and congenital anomalies in a contemporary, diverse population of women with pregestational diabetes.

Research design and methods: This is a retrospective cohort study of all pregnant women with pregestational diabetes at a single institution (2003-2017) in the USA. The primary outcome was frequency of major or minor congenital anomalies. Glycemic control was assessed by periconception glycosylated hemoglobin (HbA1c). The association of periconception HbA1c with pregnancy outcomes was assessed using bivariable and multivariable analyses.

Results: Our sample included 351 women, of which 63.8% had type 2 diabetes. Our study cohort is racially and ethnically diverse, with approximately equal numbers of women identifying as white non-Hispanic, black non-Hispanic and Hispanic, with 3.4% identifying as Asian. Of these 351 women, 52 (14.8%) had a fetus with a congenital anomaly, of whom the majority (n=43) had a major anomaly. Over half (51.1%) of all major anomalies were cardiovascular. Compared with the group with the best glycemic control (HbA1c ≤7.4%), which had an anomaly frequency of 10.2%, the frequency of congenital anomalies increased significantly with each category of worsening glycemic control (HbA1c 7.5%-9.4%: 20.6%, adjusted OR (aOR) 2.35, 95% confidence interval (CI) 1.08 to 5.13; HbA1c 9.5% to 11.4%: 25.8%, aOR 2.86, 95% CI 1.08 to 7.59; HbA1c ≥11.5%: 37.5%, aOR 7.66, 95% CI 2.27 to 25.9).

Conclusion: In a diverse cohort of women with pregestational diabetes, higher periconception HbA1c, especially HbA1c >9.5, was significantly associated with major congenital fetal anomalies. Our study sample is reflective of the current population of pregnant women with diabetes, including women with type 2 diabetes and from racial and ethnic minorities.