Maternal vitamin D status has been positively associated with infant bone mass in observational studies. We therefore evaluated whether 1000 IU/day cholecalciferol during pregnancy would lead to greater offspring bone mass at birth, in a UK, multicentre, randomised, double-blind, placebo-controlled trial (MAVIDOS, ISRCTN82927713).
At 12 weeks gestation, pregnant women with a serum 25-hydroxyvitamin D [25(OH)D] 25-100 nmol/l were randomised to either 1000 IU cholecalciferol or matched placebo daily until delivery. Plasma 25(OH)D concentration was measured centrally at 14 and 34 weeks gestation (Diasorin Liaison). Within 2 weeks after birth, infant whole body bone mineral content (BMC) was assessed by Dual-Energy X-ray Absorptiometry (Hologic Discovery, Hologic; or iDXA, GE-Lunar; measurements standardised).
Infants born to mothers supplemented with cholecalciferol had non-significantly greater whole body BMC than infants born to mothers taking placebo (total n=665; mean (S.D.) 61.6 (11.7)g vs 60.5 (11.1)g, respectively, P=0.21). However, in a pre-specified analysis, there was an interaction between season of birth and treatment allocation (P=0.04): infants born in winter (DecemberFebruary) to mothers randomised to cholecalciferol had greater BMC than those randomised to placebo (63.0±10.8 g vs 57.5±10.9 g, P=0.004), a difference>0.5S.D. Similar patterns were observed for bone area and bone mineral density. At 34 weeks gestation, the proportion of women with vitamin D sufficiency [25(OH)D>50 nmol/l] was increased (83.4% vs 36.5%, P<0.001) amongst those who received cholecalciferol compared to placebo. In the placebo group, 25(OH)D declined from 14 to 34 weeks gestation in women who gave birth in winter or spring, but rose in those taking cholecalciferol, irrespective of birth season (P<0.001). No safety issues were identified.
Maternal gestational supplementation with 1000 IU cholecalciferol increases bone mass in UK infants born during winter months, and prevents the seasonal decline in 25(OH)D in these mothers. The findings inform public health policy relating to antenatal vitamin D supplementation. *CC and NCH are joint first author.
14 - 17 May 2016
European Calcified Tissue Society