News article

Bone mass in winter-born infants improves with vitamin D in pregnancy

Posted:  Monday, March 07, 2016

Vitamin D supplements in pregnancy increase bone mass in babies

Vitamin D supplements during pregnancy improve bone mass in winter-born infants! Past observational studies have linked maternal vitamin D deficiency during pregnancy with reduced bone mass in the offspring. A new clinical study has now confirmed that a high maternal vitamin D level during pregnancy is associated with increased bone mass of the baby.

The researchers conducted a randomized placebo-controlled trial known as the Maternal Vitamin D Osteoporosis Study (MAVIDOS) to confirm the impact of pregnancy vitamin D supplementation on the bone health status of the babies. Around 1134 women who were 14 – 17 weeks pregnant and had low-to-normal levels of vitamin D were recruited from three UK study sites. One group received oral placebo capsule daily (n= 569) and the second group received a 25µg vitamin D capsule daily (n= 565) until delivery of the baby.

The bone health of babies was assessed using bone density scanning. The study indicated that there was no significant difference in the mean bone mass of babies born to women receiving vitamin D supplements and placebo (61.6g vs. 60.5g, respectively). However, babies born during winter months to mothers who were on vitamin D supplements had significantly higher bone mass (63.0 g) than those born to mothers receiving placebo (57.5 g).

Dr. Nicholas Harvey, a Professor of Rheumatology and Clinical Epidemiology at the MRC Lifecourse Epidemiology Unit, University of Southampton, explained: "Babies' bones strengthen during the last stages of pregnancy. Since sunlight is our most important source of vitamin D, mothers' levels of vitamin D tend to drop from summer to winter, and babies born in the winter months tend to have lower bone density than those born during the summer. The MAVIDOS Trial has given us the first evidence that supplementing mothers with vitamin D during pregnancy counteracts the seasonal drop in maternal vitamin D levels and may help to ensure good bone development in these winter births."