Low vitamin D levels associated with infertility

This study looked at vitamin D levels and pregnancy rates in patients undergoing in vitro fertilization (IVF). The study found that pregnancy rates were signficantly higher in the patients who had higher vitamin D levels.

Vitamin D is important for good health. The main source of vitamin D is from the action of sunlight on the skin. Few foods naturally contain vitamin D, though it is added by manufacturers to foods. It is also available as a supplement.

Vitamin D can affect fertility in mammals, but human studies are inconclusive.

In vitro fertilization (IVF) is a procedure where the egg is fertilized by the sperm outside the body, and then implanted into the woman's uterus. It can be used when there is unexplained infertility, or when a woman's fallopian tubes (the tubes that take the female egg from the ovaries to the uterus) are damaged or are missing. It is not clear whether vitamin D levels affect pregnancy rates following IVF.

This study examined the association between vitamin D and IVF success rates.

This study included 335 women. Vitamin D levels were measured for each woman prior to undergoing IVF. 154 women were deficient in vitamin D (levels less than 20 ng/mL), and 181 women were not deficient, with vitamin D levels greater than 20 ng/mL.

Pregnancy rates were 20% for the women deficient in vitamin D, and 31% for the women with higher levels of vitamin D. Women with vitamin D levels over 20 ng/mL were 2.15 times more likely to acheive pregnancy than women with lower levels. Women with the highest vitamin D levels (30 ng/mL or higher) had the highest chances of pregnancy.

The study concluded that vitamin D is an important factor influencing female fertility and IVF outcome. 

The study did not establish whether vitamin D deficiency caused infertility, only that there was an assoication.

If you are planning a pregnancy, you should discuss your vitamin D levels with your doctor. Vitamin D supplements may help if you have insufficient levels of this vitamin.