In August 2018 researchers from the USA published the results of their study to assess the relationship between vitamin D deficiency and reproductive outcomes after ovarian stimulation in 607 women with polycystic ovary syndrome and 647 women with unexplained infertility. Results showed that in women with polycystic ovary syndrome, those with vitamin D deficiency (under 20 ng/mL or 50 nmol/L) were less likely to ovulate following ovarian stimulation and experienced a 40% lower chance of a live birth than those who were not deficient. In women with unexplained infertility, no significant association was seen between low vitamin D levels and live birth. Women from both groups who did fall pregnant following ovarian stimulation were seen to have an increased risk of experiencing a miscarriage if they had low levels of vitamin D.
Butts SF et al. Vitamin D Deficiency is Associated with Poor Ovarian Stimulation Outcome in PCOS but not Unexplained Infertility. J Clin Endocrinol Metab. 2018 Aug 3. [Epub ahead of print]