Edelson PK, James KE, Leong A, et al. - Researchers intended to determine if there is an association between hemoglobin A1c (HbA1c) levels and glucose tolerance across pregnancy and postpartum. They performed oral glucose tolerance testing (OGTT) and HbA1c measurements at 10-15 weeks gestation, 24-30 weeks gestation (N = 73), and 6-24 weeks postpartum (N = 42) in a longitudinal study of pregnant women with gestational diabetes risk factors (N = 102). According to results, mean OGTT glucose increased between 10-15 and 24-30 weeks gestation, whereas HbA1c declined during the same time period. Findings suggested that HbA1c precisely reflects glycemia in the first trimester, but underestimates the intolerance to glucose in the late second trimester. Greater underestimation is associated with lower hemoglobin levels. Gestational age and maternal hemoglobin accounting may improve the clinical understanding of the HbA1c levels during pregnancy.