Longitudinal Maternal Vitamin D Status during Pregnancy Is Associated with Neonatal Anthropometric Measures

Findings on maternal 25-hydroxyvitamin D (25[ OH] D) and neonatal anthropometry are inconsistent, and may at least be partly due to variations in gestational week (GW) of 25(OH) D measurement and the lack of longitudinal 25(OH) D measurements across gestation. The aim of the current study was to examine the associations of longitudinal measures of maternal 25(OH) D and neonatal anthropometry at birth. This study included 321 mother-offspring pairs enrolled in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies-Singletons. This study was a prospective cohort design without supplementation and without data on dietary supplementation. Nevertheless, measurement of plasma 25(OH) D reflects vitamin D from different sources, including supplementation. Maternal concentrations of total 25(OH) D were measured at 10-14, 15-26, 23-31, and 33-39 GW and categorized as < 50 nmol/L, 50-75 nmol/L, and > 75 nmol/L. Generalized linear models were used to examine associations of 25(OH) D at each time-point with neonate birthweight z-score, length, and sum of skinfolds at birth. At 10-14 GW, 16.8% and 49.2% of women had 25(OH) D < 50 nmol/L and between 50-75 nmol/L, respectively. The association of maternal 25(OH) D with neonatal anthropometry differed by GW and women's prepregnancy BMI (normal (< 25.0 kg/m(2)), overweight/obese (25.0-44.9 kg/m(2))). All analyses were stratified by prepregnancy BMI status. Among women with an overweight/obese BMI, 25(OH) D < 50 nmol/L at 10-14GWwas associated with lower birthweight z-score (0.56; 95% CI: 0.99, 0.13) and length (1.56 cm; 95% CI: 3.07, 0.06), and at 23-31 GW was associated with shorter length (2.77 cm; 95% CI: 13.38, 4.98) and lower sum of skinfolds (9.18 mm; 95% CI: 13.38, 4.98). Among women with a normal BMI, 25(OH) D < 50 nmol/L at 10-14 GW was associated with lower sum of skinfolds (2.64 mm; 95% CI: 5.03, 0.24), at 23-31 GW was associated with larger birthweight z-scores (0.64; 95% CI: 0.03, 1.25), and at 33-39 GW with both higher birthweight z-score (1.22; 95% CI: 0.71, 1.73) and longer length (1.94 cm; 95% CI: 0.37, 3.52). Maternal 25(OH) D status during pregnancy was associated with neonatal anthropometric measures, and the associations were specific to GW of 25(OH) D measurement and prepregnancy BMI.