Impact of Maternal HbA1c Levels ≤6% and Race in Nondiabetic Pregnancies on Birthweight and Early Neonatal Hypoglycemia

Objective: To evaluate whether pregnancy glycated hemoglobin (HbA1c) levels of ≤6% and maternal race impacts neonatal hypoglycemia and birthweight, and whether diabetes and beta blocker use during pregnancy additively impacts neonatal outcomes. Study design: Retrospective chart review of 4769 infants born at ≥34 weeks; 21 482 glucose measurements were assessed. Predefined groups were infants born to mothers without documented pregnancy conditions (group N), prenatal exposure of beta blockers (group B), diabetes (group D), or both (group DB). Results: In group N, both in Caucasian (Caucasian, n = 1756; β = 2.6, P < .001) and African American (n = 1872; β = 2.2, P = .002) race, there was a direct relationship between pregnancy HbA1c levels and birthweight. HbA1c (aOR 1.8; 95% CI [1.3-2.5]) levels, maternal race, prematurity, cesarean delivery, and birth weight predicted hypoglycemia. Each 0.1% increase in HbA1c levels between 4.8 and 6 increased the odds of neonatal hypoglycemia by 6.4% in African American (β 0.62, SE 0.22, P = .01) and by 12.0% in Caucasian (β 1.13, SE 0.23 P < .001) population. The odds of neonatal hypoglycemia were 1.7 (group B), 2.1 (group D), and 3.1 (group DB) times higher compared with group N. Conclusions: Pregnancy HbA1c levels between 4.8% and 6.0% considered acceptable during pregnancy impacts neonatal hypoglycemia and birthweight especially in Caucasian race. A third trimester HbA1c >5.2 is a potential risk factor for neonatal hypoglycemia, especially in preterm infants. Although we report new findings on the relationship between maternal HbA1c levels and neonatal outcomes, a prospective study is required to validate our findings and determine “optimal” HbA1C levels during pregnancy.