Elevated HbA1c on universal prenatal screening is associated with decreased postpartum weight retention

Abstract

Objective To determine the association of an elevated hemoglobin A1c (HbA1c) as part of an early pregnancy universal screening protocol and postpartum (PP) weight retention in the absence of a diagnosis of diabetes. Methods This is a retrospective cohort study of patients who underwent universal HbA1c screening with initial prenatal labs (≤16 weeks) over a 2-year period (2016–2018) at a single urban tertiary care center. An elevated HbA1c was defined as 5.7–6.4%. All patients who delivered ≥32 weeks with documented weights at first prenatal visit, delivery, and PP visit were included. Patients with preexisting or gestational diabetes, multiple gestation, fetal demise, or no glucose tolerance screening were excluded. Body mass index (BMI) was calculated and gestational weight gain was assessed by National Academy of Medicine (NAM) guidelines. The primary outcome was PP weight retention among patients with normal versus elevated HbA1c. Results 2,284 patients met inclusion criteria, of whom 2015 (88.2%) had a normal HbA1c and 269 (11.8%) had an elevated HbA1c. Compared to patients with a normal HbA1c, patients with an elevated HbA1c were more likely to be non-Hispanic black, multiparous, or publicly insured. They were also more likely to enter pregnancy obese. Patients with an elevated HbA1c gained less weight during pregnancy compared to those with normal HbA1c; however, this was no longer significant after adjusting for pre-pregnancy BMI. In both groups, almost half of patients exceeded NAM guidelines for gestational weight gain during the pregnancy. Patients with an elevated HbA1c had significantly less PP weight retention (2.2 vs. 4.5 kg, p < .001) compared to patients with a normal HbA1c. After adjusting for differences in baseline characteristics, the association between HbA1c and PP weight retention remained significant (B = −0.86, p < .003). More patients in the elevated HbA1c group returned to their pre-pregnancy weight or less by the PP visit. In all BMI categories, those who exceeded NAM guidelines had greater postpartum weight retention compared to those that met guidelines Conclusion Among patients not diagnosed with diabetes, elevated HbA1c in early pregnancy is associated with similar gestational weight gain but significantly less postpartum weight retention compared to those with normal HbA1c.