Maternal vitamin D levels during pregnancy have no effect on offspring’s bone health in later life

by Bruce Sylvester – taken from The Lancet – Results from a new retrospective study of data from a large mother-child population in the UK suggest that maternal vitamin D levels during pregnancy are not associated with offspring bone health in later life.

The research was published online on March 18, 2013 in The Lancet. It is the largest observational study to date of the effects of maternal vitamin D levels in pregnancy to offspring bone health.

The study is part of the Avon Longitudinal Study of Parents and Children (ALSPAC), also known as Children of the 90s, a long-term health research project enrolling more than 14,000 mothers during pregnancy in 1991 and 1992, and following the subsequent health and development of the mothers and children.

Led by Professor Debbie Lawlor of the University of Bristol (UK), the investigative team assessed vitamin D levels in a subset of 3,960 pregnant women, using data from all three trimesters.

When the children were an average age of nine years and 11 months, the investigators evaluated bone mineral content (BMC) using dual-energy X-ray absorptiometry.

They found no significant association between a mother’s vitamin D levels and their child’s BMC.

Notably, the investigators reported that even though non-white mothers and those who smoked during pregnancy tended to have lower overall vitamin D levels overall, there no effect on offspring bone health.

In a Comment, Professor Philip Steer of Imperial College London, UK, said, “In view of the inconsistency in results [of previous studies], it might seem unclear why vitamin D supplementation is officially recommended for all pregnant and breastfeeding women.”

He added that, “The safest approach is probably routinely to supplement pregnant women at greatest risk, as defined by the NICE guidelines: women of south Asian, black African, black Caribbean, or Middle Eastern origin, women who have limited exposure to sunlight (eg, those who are predominantly housebound or are generally fully covered when outdoors), women who eat a diet particularly low in vitamin D (eg, no oily fish, eggs, meat, or vitamin D-fortified margarine or breakfast cereal), and women with a body-mass index higher than 30 kg/m² before pregnancy. For other women, the optimum approach is unclear, and long-term randomised trials of supplementation are justified.”