AimPrognosis of treated hyperglycemia in pregnancy (HIP) may differ according to whether diagnosis following an oral glucose tolerance test (OGTT) is based on high fasting and/or high post-load glucose values. MethodsFrom a multiethnic prospective study, we included 8,339 women screened for HIP after 22 weeks of gestation. We evaluated the risk of large-for-gestational-age (LGA) infant (primary endpoint) and other adverse pregnancy outcomes according to HIP status in four groups defined as follows: no HIP (n = 6,832, reference); isolated fasting HIP (n = 465), isolated post-load HIP (n = 646), and fasting and post-load HIP (n = 396). ResultsAfter adjusting for age, body mass index, ethnicity, smoking during pregnancy and parity, compared with no HIP, the adjusted odds ratios [95% confidence interval] for LGA infant were higher in the isolated fasting HIP (1.47 [1.11–1.96]) and fasting and post-load HIP (1.65 [1.23–2.21]) groups, but not in the isolated post-load HIP (1.13 [0.86–1.48]) group. The adjusted odds ratios for preterm delivery and neonatal intensive care unit were higher in the post-load HIP group (1.44 [1.03–2.03] and 1.28 [1.04–1.57], respectively), the fasting and post-load HIP group (1.81 [1.23–2.68] and 1.42 [1.10–1.81], respectively) but not in the isolated fasting HIP group (1.34 [0.90–2.00] and 1.20 [0.94–1.52], respectively). ConclusionDespite glucose-lowering care and adjustment for confounders, compared with no HIP, fasting HIP was associated with a higher rate of LGA infant, whereas post-load HIP was associated with higher preterm delivery and neonatal intensive care unit admission rates.