Health studies about vitamin D and female fertility:
BMI and Season are Associated with Vitamin D Deficiency in Women with Impaired Fertility: A Two-Centre Analysis (2016)
Conclusion: A study of women with impaired fertility found the overwhelming majority of them had low vitamin D levels.
Conclusion: A study of pregnancy outcomes in 335 women undergoing in vitro fertilization found that the women with the highest vitamin D levels also had the highest pregnancy rates.
Conclusion: A study of 99 women undergoing in vitro fertilization found that those with higher vitamin D levels also had higher pregnancy and live birth rates.
Effects of 25OHD Concentrations on Chances of Pregnancy and Pregnancy Outcomes: A Cohort Study in Healthy Danish Women (2012)
Conclusion: A study of 153 women trying to get pregnant found that those with lower vitamin D levels had a higher risk of miscarriage.
Note: This is a detailed, technical article covering the role of vitamin D in male and female fertility. Did you know that even sperm have vitamin D receptors?
Conclusion: Female rats with better vitamin D levels were found to have better fertility compared to vitamin D-deficient rats.
Conclusion: Vitamin D-deficient female rats were found to be significantly less fertile than those with better vitamin D levels.