Studies about vitamin D and fertility:
Vitamin D Treatment Improves Levels of Sexual Hormones, Metabolic Parameters and Erectile Function in Middle-Aged Vitamin D Deficient Men (2017)
Conclusion: In a 12-month study of 102 vitamin D-deficient middle-aged men, monthly high-dose vitamin D therapy raised their testosterone levels, improved erectile function, and reduced body fat.
Vitamin D Deficiency and Low Ionized Calcium Are Linked with Semen Quality and Sex Steroid Levels in Infertile Men (2016)
Conclusion: In a prospective study of 1248 Danish men, those with adequate vitamin D levels had slightly higher testosterone levels and much higher sperm counts compared to those with deficient vitamin D levels.
Conclusion: 12 months of vitamin D therapy revealed to be effective for improving testosterone production in rats and for reversing testicular damage from hyperglycemia-induced inflammation.
Conclusion: This study of fertility in Chinamen found that fertile men had slightly higher vitamin D levels compared to infertile men.
Association of Vitamin D Status with Semen Quality and Reproductive Hormones in Iranian Subfertile Men (2016)
Conclusion: In a study of 278 subfertile Iranian men, a positive correlation was found between vitamin D levels and sperm motility.
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.
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.