Should We Be Monitoring Vitamin D Levels In Our Infertile Patients?
There is growing evidence that vitamin D is strongly associated with reproductive function. Deficiency of the hormonally active form of vitamin D has been associated with infertility and pregnancy complications. Several studies have reported that pregnancy rates in patients undergoing in-vitro fertilization are higher in women who have ample blood levels of vitamin D compared to women who are deficient in vitamin D. A recent study from Columbia University in New York and the University of Southern California (Rudick, Ingles, Chung, et. al. Fertility and Sterility, Vol. 101, No. 2, February, 2014) suggests that patients with ample vitamin D levels had significantly higher pregnancy rates compared with women with deficient levels of this vitamin, and their study design indicates that the improved outcomes were achieved through improvement in the receptivity of the uterine lining.
In this study, vitamin D levels were measured in a group of egg donor recipients. The patients were divided into groups based upon their serum levels of 25(OH)D. The groups were as follows:
Vitamin D deficiency: < 20 ng/ml
Vitamin D insufficiency: 20-30 ng/ml
Vitamin D replete: > 30ng/ml
The data generated in this study showed that the pregnancy rates progressively decreased as vitamin D levels decreased. The pregnancy rates were 74% in the vitamin D replete group compared to only 35% in the vitamin D deficient group. Because donated eggs were utilized in this study, the beneficial effect observed in the vitamin D “replete” group could not have been the result of vitamin D on the embryos. This suggests that the benefits of ample vitamin D were on the endometrium. Studies have demonstrated that there is complex cellular communication between the embryo and the endometrium around the time of implantation and vitamin D signaling is intimately involved in this process. While this study did not look at vitamin D supplementation, it would be interesting to construct a study looking at egg donor recipients with planned vitamin D supplementation for patients with insufficiency or deficiency. While we wait for this study to be done, it may be advantageous to begin measuring vitamin D levels routinely in our infertility patients and recommending supplementation in those who demonstrate deficiency.