Vitamin D before and during pregnancy Back in January 2011 the online BBC news service reported on recommendations by the Scottish government to women who were planning a pregnancy to take vitamin D supplements. The news story went on to describe comment that many women of childbearing age in Scotland are known to be deficient in key nutrients such as iron, calcium, folate and vitamin D. Women currently take folic acid supplements but the suggestion from the Scottish government to take vitamin D is fairly recent. The main source of vitamin D is sunshine and women living in northern latitudes such as Scotland often do not get enough to ensure healthy growth of the foetus.
Use of supplements during pregnancy has always been a concern but vitamin D supplements are looking to be quite safe. Researchers writing in the Journal of Bone and Mineral Research report that even a vitamin D supplementation in healthy pregnant women was safe and effective in raising circulating vitamin D to a level thought by some to be optimal. The study also found no adverse effects of vitamin D supplementation, in women or their newborns. The lead researcher, Dr Bruce Hollis from the Medical University of South Carolina in Charleston USA commented “Vitamin D supplementation during pregnancy remains controversial largely due to severe misconceptions about the potential harm it may cause to the fetus,” said Dr Hollis. “Surprisingly the scientific debate has made little progress since Dr. Gilbert Forbes made a recommendation of 200 IU (international units) per day in 1963, which was based on a hunch!” Dr Hollis’ team monitored the pregnancies of 350 women, from a variety of ethnic and socio-economic backgrounds, who were all between 12 and 16 weeks into gestation.
The women were randomly assigned to one of three groups. One group received 400 IU of vitamin D per day, the second group received 2,000 IU per day and the third received 4,000 IU daily. The team found that women who received the highest level of supplementation were more likely to achieve and sustain the desired level of circulating levels of vitamin D throughout their pregnancy. Moreover, the researchers found that pregnant women who received lower levels of vitamin D supplementation did not attain the threshold circulating level of the vitamin.
Dr Hollis concluded, “following decades of speculation into its safety our research has demonstrated vitamin D supplementation to be both safe and effective.”
Hollis. B, Johnson. D, Hulsey. T, Ebeling. M, Wagner. L, “Vitamin D Supplementation during Pregnancy: Double Blind, Randomized Clinical Trial of Safety and Effectiveness”, Journal of Bone and Mineral Research, Wiley-Blackwell, June 2011