By David Kreiner, MD and Briana Rudick, MD
Vitamin D is a fat soluble vitamin that is present in a variety of forms but has recently been recognized as playing a critical role in reproduction. It is essential in the production of sex hormones in the body. It is thought that a deficiency of Vitamin D may lead among other things to ovulation disorders.
It has been demonstrated that Vitamin D deficient rats had a 75% reduced fertility and a 50% smaller litter size that was corrected with Vitamin D treatment. In addition, sperm motility in males was reduced in the presence of a Vitamin D deficiency.
A recent study at the Yale University School of Medicine revealed that only 7% of 67 infertile women studied had normal Vitamin D levels and not a single woman with an ovulatory disorder had normal levels. Nearly 40% of women with ovulatory dysfunction had a clinical deficiency of Vitamin D.
At the American Society of Reproductive Medicine conference this year, a study presented by Dr. Briana Rudick from USC showed that a deficiency of Vitamin D can also have a detrimental effect on pregnancy rates after IVF, possibly through an effect on the[O1] endometrial lining of the uterus. In her study only 42% of the infertile women going through IVF had normal Vitamin D levels. Vitamin D levels did not impact the number of ampules of gonadotropin utilized nor the number of eggs stimulated, embryos created nor embro quality. However, Vitamin D levels did significantly effect pregnancy rates even when controlled for number of embryos transferred and embryo quality. In this study the pregnancy rate dropped from 51% in Caucasian women undergoing IVF who had normal Vitamin D levels to 44% in those with insufficient levels and 19% in those that were deficient.
Vitamin D deficiency has also been associated with poor pregnancy outcomes including preeclampsia and gestational diabetes
Vitamin D can be obtained for free by sitting out in the sun and getting sun exposure on the arms and legs for 15-20 minutes per day during peak sunlight hours. The sunlight helps the skin to create Vitamin D3 that is then transformed into the active form of Vitamin D by the kidneys and liver. An oral supplement is available also in the form of Vitamin D3, with a minimum recommended amount of 1000 IU a day for women planning on becoming pregnant. For those with clinical insufficiencies a higher dose may be administered by injection.
[O1] Our study and many others suggest that the effect is endometrial, but we don’t know for sure.