Gestational diabetes is associated with increased birth size. Blood glucose concentrations within the nondiabetic range affect birth size but whether this influences postnatal growth is unclear. Methods: We measured fasting blood glucose concentrations (FBG) in 1650 singleton Caucasian pregnancies at 12 and 28 weeks' gestation and related values to birth weight and weight at 12 and 24 months of age. Pregnancies complicated by antepartum hemorrhage, gestational diabetes, preeclampsia, and

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... rity were excluded. Results: Mean maternal age was 30 years and 49% were primiparous. There was a weak relationship between birth weight (z score) and FBG at 12 (r ϭ 0.1; P ϭ .006) and 28 (r ϭ 0.1; P Ͻ .001) weeks. FBG at 12 and 28 were correlated (r ϭ 0.3; P Ͻ .001). Mothers at 12 and 28 weeks of pregnancy with higher FBG were shorter and heavier. The relationship between FBG at 12 and 28 weeks and birth weight was not observed in primiparous women and FBG was not associated with weight at any postnatal time point. Conclusions: These data suggest that in a low-risk United Kingdom pregnancy cohort FBG concentrations in the nondiabetic range affect birth weight in multiparous women. The effect is small (50 g change in birth weight/1 mmol/L FBG change) and does not persist into postnatal life. This implies a limited role for maternal glucose status within the normal range in determining size in infancy. (J Clin Endocrinol Metab 98: 4916 -4922, 2013)