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Pregnant women not taking enough vitamin D

Feb. 2012

Vitamin D

In 2011, a number of studies identified a connection between low vitamin D levels and an increased risk of gestational diabetes. One of these, published online in Diabetic Medicine in December1, was led by Dr. Lorraine Lipscombe, Women’s College scientist and endocrinologist and assistant professor of medicine at the University of Toronto.

“Our study adds to the growing body of evidence calling for a randomized controlled trial to test whether vitamin D supplementation can lower the rate of gestational diabetes,” says Lipscombe.

A trial would confirm whether vitamin D depletion causes or merely coincides with gestational diabetes mellitus (GDM). It could also show whether vitamin D could reverse or improve GDM in pregnant women.

Poorly controlled pre-existing diabetes and GDM are not only unsafe for women, but also increase the risk of macrosomia (big baby syndrome) and future diabetes in babies. Studies have also shown that supplemental vitamin D may prevent or delay the onset of diabetes and reduce complications for those who have already been diagnosed. But since these studies weren’t done in pregnant women, doctors remain cautious in their recommendations.

“Doctors are rightly very careful to avoid harm, so obstetricians and general practitioners still aren’t routinely recommending supplementation to their pregnant patients,” Lipscombe says.

“But we do know that women who are pregnant and breastfeeding need more vitamin D.”

Pregnant women in northern communities are already counselled to supplement with vitamin D each day, yet these recommendations haven’t yet translated to southern Canadian communities, where office jobs and winter weather often keep people out of the sun and vitamin D-depleted. Vitamin D levels tend to be even lower in people with darker skin – something to consider in multi-cultural areas.

“When it comes to the evidence around vitamin D, the recommendations are really lagging behind the science.”

> read article

1 Parlea L, Bromberg IL, Feig DS, Vieth R, Merman E, Lipscombe LL. Association between serum 25 hydroxyvitamin D in early pregnancy and risk of gestational diabetes mellitus. Diabetic Medicine. 2011 Dec 12 [Epub ahead of print]


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