Association of maternal vitamin D status during pregnancy with bone-mineral content in off spring: a prospective cohort study

Background Maternal vitamin D status in pregnancy is a suggested determinant of bone-mineral content (BMC) in off spring, but has been assessed in small studies. We investigated this association in a large prospective study. Methods Eligible participants were mother-and-singleton-off spring pairs who had participated in the Avon Longitudinal Study of Parents and Children, and in which the mother had recorded measurements of 25(OH) D concentration in pregnancy and the off spring had undergone dual-energy x-ray absorptiometry at age 9-10 years. 25(OH) D concentrations in pregnancy were assessed per 10.0 nmol/L and classified as sufficient (more than 50.00 nmol/L), insufficient (49.99-27.50 nmol/L), or deficient (lower than 27.50 nmol/L). Associations between maternal serum 25(OH) D concentrations and off spring total body less head (TBLH) and spinal BMC were assessed by trimester. Results 3960 mother-and-off spring pairs, mainly of white European origin, were assessed (TBLH BMC n=3960, spinal BMC n=3196). Mean off spring age was 9.9 years. 2644 (67%) mothers had sufficient, 1096 (28%) insufficient, and 220 (6%) deficient 25(OH) D concentrations in pregnancy, but TBLH and spinal BMC did not differ between off spring of mothers in the lower two groups versus sufficient 25(OH) D concentration. No associations with off spring BMC were found for any trimester, including the third trimester, which is thought to be most relevant (TBLH BMC confounder-adjusted mean difference -0.03 g per 10.0 nmol/L, 95% CI -1.71 to 1.65; spinal BMC 0.04 g per 10.0 nmol/L, 95% CI -0.12 to 0.21). Conclusions We found no relevant association between maternal vitamin D status in pregnancy and off spring BMC in late childhood.