Although I rarely write articles about pregnancy, I couldn’t pass on a study that appeared in the April issue of the American Journal of Obstetrics and Gynecology. The authors from McGill University tested Vitamin D levels in a group of pregnant women in Halfax, Nova Scotia and Quebec City (not sunny places).169 of these women had preeclampsia or hypertension in pregnancy and 1975 controls had normal blood pressure and no signs of preeclampsia.
Preeclampsia is a syndrome in which there is an elevation of blood pressure in pregnancy together with loss of protein in the urine. Other signs and symptoms can include edema, vision changes, loss of clotting factors (platelets), impaired liver function and shortness of breath. Ultimately if not treated, this syndrome can lead to seizures (eclampsia). It is the leading cause of maternal illness and death. We still don’t know exactly what causes preeclampsia and how to prevent it.
According to the authors of this article, low vitamin D status is estimated to account for as much as 10% of pregnancy complications in Canada. The American Institute of Medicine (IOM) defines vitamin D deficiency as a serum (blood) 25 – hydroxy vitamin D of less than 30 nmol/L. The IOM recommends that the level for women of reproductive age be greater than 50 nmol/M.
The Canadian study evaluated those women who had vitamin D deficiency before 20 weeks of gestation to ascertain if they had an increased risk for developing preeclampsia. The researchers found that maternal vitamin D deficiency defined as less than 30nmol/L was associated with doubled odds of preeclampsia compared to women who had concentrations greater than 50 nmol/L.
Vitamin D supplementation in pregnancy helps to increase maternal concentrations of 25 hydroxy vitamin D. Unfortunately, the exact dosage that will decrease the risk of preeclampsia is not established. To date there have been no randomized controlled trials published on vitamin D supplementation alone and risk for preeclampsia. However, in the present study a level greater than 50 nmol/L was associated with a decrease risk for preeclampsia and this may correspond to 600 international units a day of vitamin D as per the recommendations of the Institute of Medicine. Based on this study the authors suggest that “reducing the proportion of women of childbearing age with vitamin D deficiency is important and may contribute to the prevention of adverse maternal health outcomes such as preeclampsia.”
Your dermatologists and I hope you are not excessively “sunning” yourself to get Vitamin D. Moreover, it is not an option in northern climates nor here in the winter months. Supplementing vitamin D appears to be a good idea at any age.