Pregnancy vitamin D supplementation and offspring bone mineral density in childhood follow-up of a randomized controlled trial.

BACKGROUND: Findings from the Maternal Vitamin D Osteoporosis Study (MAVIDOS) trial demonstrated a positive effect of gestational cholecalciferol supplementation on offspring bone mineral density (BMD) at age 4 y. Demonstrating the persistence of this effect is important to understanding whether maternal vitamin D supplementation could be a useful public health strategy to improving bone health. OBJECTIVES: We investigated whether gestational vitamin D supplementation increases offspring BMD at ages 6-7 y in an exploratory post-hoc analysis of an existing trial. METHODS: In the MAVIDOS randomized controlled trial, pregnant females <14 wk' gestation with a singleton pregnancy and serum 25-hydroxyvitamin D 25-100nmol/l at 3 United Kingdom hospitals (Southampton, Sheffield, and Oxford) were randomly assigned to either 1000 IU/d cholecalciferol or placebo from 14 to 17-wk gestation until delivery. Offspring born at term to participants recruited in Southampton were invited to the childhood follow-up at ages 4 and 6-7 y. The children had a dual-energy X-ray absorptiometry (DXA, Hologic discovery) scan of whole-body-less-head (WBLH) and lumbar spine, from which bone area, bone mineral content (BMC), BMD, and bone mineral apparent density (BMAD) were derived. Linear regression was used to compare the 2 groups adjusting for age, sex, height, weight, duration of consumption of human milk, and vitamin D use at 6-7 y. RESULTS: A total of 454 children were followed up at ages 6-7 y, of whom 447 had a usable DXA scan. Gestational cholecalciferol supplementation resulted in higher WBLH BMC [0.15 SD, 95% confidence interval (CI): 0.04, 0.26], BMD (0.18 SD, 95% CI: 0.06, 0.31), BMAD (0.18 SD, 95% CI: 0.04, 0.32), and lean mass (0.09 SD, 95% CI: 0.00, 0.17) compared with placebo. The effect of pregnancy cholecalciferol on bone outcomes was similar at ages 4 and 6-7 y. CONCLUSIONS: Supplementation with cholecalciferol 1000 IU/d during pregnancy resulted in greater offspring BMD and lean mass in mid-childhood compared with placebo in this exploratory post-hoc analysis. These findings suggest that pregnancy vitamin D supplementation may be an important population health strategy to improve bone health. TRIAL REGISTRATION NUMBER: This trial was registered at the ISRCTN (https://doi.org/10.1186/ISRCTN82927713) as 82927713 and EUDRACT (https://www.clinicaltrialsregister.eu/ctr-search/trial/2007-001716-23/results) as 2007-001716-23.