(786) Hemoglobin A1c among patients without diabetes and risk of large for gestational age neonates

Objective: To describe the association between an early pregnancy Hemoglobin A1c (HbA1c) as obtained on universal screening with large for gestational age (LGA) neonates among patients without a diagnosis of diabetes.

Study Design: This is a retrospective cohort study of patients with a singleton pregnancy who underwent universal HbA1c screening in early pregnancy (≤16 weeks) at a single urban tertiary care center between 2016 and 2018. We included those who delivered ≥32 weeks with documented maternal weight at the first prenatal visit and at delivery. We excluded patients with preexisting or gestational diabetes, fetal demise, or those without glucose tolerance screening. The exposure of interest was an elevated A1c (5.7-6.4%). The primary outcome was a diagnosis of LGA, defined by a birthweight ≥90thile by INTERGROWTH-21.

Results: Of 2594 eligible patients, 2272 (87.6%) had normal HbA1c levels (< 5.7%) and 322 (12.4%) had elevated HbA1c (5-7-6.4). Patients with an elevated HbA1c were more likely to be older, Black, multiparous, publicly-insured, obese at the initial prenatal visit, or have chronic hypertension compared to those with a normal HbA1c level. There was no significant difference in the rate of LGA neonates between patients with an elevated compared to normal HbA1c (12.7% vs. 11.9%, p=0.67). Among patients with obesity (BMI ≥30), however, an increasing HbA1c was significantly associated with LGA (OR=1.95, 95% CI 1.04-3.678). This remained significant after adjusting for maternal age, parity, insurance status, and chronic hypertension (aOR=2.85, 95% CI 1.41-5.74). The relationship between HbA1c and LGA remained regardless of whether Institute of Medicine gestational weight gain guidelines were met or exceeded.

Conclusion: In obese patients, an elevated HbA1c in early pregnancy increases the risk of delivering an LGA infant in the absence of diabetes and irrespective of weight gain in pregnancy. This underscores the importance of achieving normal HbA1c levels prior to pregnancy for improved neonatal outcomes.