I would like to update you on two recent studies that provide further knowledge on this topic. Keep in mind; Vitamin D status is commonly assessed by measuring serum 25-OH Vitamin D levels. Typical categories include:

• Sufficient: Greater than (>) 30 ng/mL
• Insufficient: 20-30 ng/mL
• Deficient: Less than (<) 20 ng/mL

In June, Researchers at Mt. Sinai Hospital in Toronto reported prospectively evaluating the Vitamin D status of 173 women undergoing IVF.  45 percent (78/173) of the women had sufficient (>30 ng/ml) 25-OH vitamin D levels while 55 percent had insufficient/deficient levels (<30 ng/mL).

This study observed that the women with sufficient 25-OH Vitamin D levels had a higher implantation rate (35%) than in the insufficient group (26%). Clinical pregnancy rates per embryo transfer were significantly higher in the sufficient group (54.7% vs. 37.9%).

The authors concluded that women with sufficient 25-OH Vitamin D levels are more likely to achieve a clinical pregnancy with IVF.

A second study was just published in the November 2013 edition of Fertility and Sterility. Of the 99 patients in this retrospective cohort study of egg donation recipients, only 35% had a 25-OH Vitamin D  > 30 ng/mL (38% were insufficient and 26% deficient).

This study observed significantly higher clinical pregnancy rates (78% vs. 37%) and live-birth rates (59% vs. 31%) in patients with 25-OH Vitamin D levels > 30 ng/mL.

The authors propose that the lower pregnancy rates observed in the patients with 25-OH Vitamin D levels < 30 ng/mL was likely mediated through localized effects on the endometrium.

These 2 studies add to our increasing understanding of the potential role of Vitamin D and human reproduction. As past studies have also indicated, patients with low serum 25-OH vitamin D levels have lower implantation and clinical pregnancy rates. It appears that oocyte production and embryo quality are not related to serum 25-OH Vitamin D status. The likely mechanism for reduced implantation and pregnancy rates appears to be the endometrium and perhaps placental development/function.

There are no studies yet published demonstrating that Vitamin D supplementation in women with insufficient or deficient levels will result in an increase in the live -birth rate. Such studies will greatly aid our understanding of Vitamin D and fertility.

Vitamin D can be safely and easily taken. It makes sense to measure 25-OH Vitamin D levels in all women attempting pregnancy, especially those undergoing IVF. In those women who are found insufficient or deficient, Vitamin D supplementation should be considered.