Low vitamin D is linked to poor fertility outcomes for women with polycystic ovarian syndrome

This study investigated vitamin D (vitD) levels in patients undergoing ovarian stimulation (OS). 

They found that low vitD reduced the chance of live birth in patients with polycystic ovary syndrome (PCOS).

Infertility can have a number of causes. One cause of infertility is polycystic ovary syndrome (PCOS). These patients may not ovulate regularly. Patients may undergo ovarian stimulation (OS) to treat this. Unexplained infertility (UI) does not have a clear cause. Women with UI may also undergo OS. It is important to understand what factors affect fertility success. 

One important factor may be Vitamin D (VitD). VitD may play an important role in human reproduction and fertility. Some studies suggest that low VitD reduces the odds of conceiving. It is unclear if VitD levels have an effect on patients undergoing OS.

This study included data from two clinical trials. One study included 607 patients with PCOS. The second trial included 647 patients with UI. The authors analyzed vitD levels. VitD was measured in blood samples. Low VitD was defined as below 20 ng/ml. Insufficient vitD was classified as 20-29 ng/ml. VitD levels greater than 30 ng/ml were considered sufficient. Live birth rate (LBR), ovulation and pregnancy outcomes were compared.

41% of PCOS patients had low vitD. 25% of UI patients had low vitD. PCOS patients with low VitD had an 18% lower rate of ovulation. LBR was 37% reduced in PCOS patients with low vitD. There was no link between low vitD and LBR in UI patients. Low VitD was associated with a 60% increase in pregnancy loss in both groups.

The authors concluded that low vitD reduced the chance of live birth in patients with PCOS.

This was a retrospective study. VitD was measured at one time-point during the study. Levels may have fluctuated during the trial. We do not know if patients were taking vitD supplements. More research is needed to understand the effect of vitD in fertility problems. 

If you have any concerns regarding fertility please consult with your physician.