Environmental influences on fertility and reproductive health

National Institute Of Environmental Health Sciences

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Linked publications & trials

Abstract

Vitamin D is known for its role in calcium absorption and bone health, but interest in its role in reproduction has been growing. Vitamin D is known as the sunlight vitamin because it is synthesized in the skin in response to ultraviolet radiation. It can also be obtained from foods or nutritional supplements. Vitamin D is metabolized to 25-hydroxyvitamin D (25(OH)D) in the liver and this is the clinical biomarker of vitamin D status. Animal models of vitamin D deficiency show disrupted ovulation and subfertility. In human, community-based samples, we published three studies that have reported associations between low 25(OH)D and long or irregular menstrual cycles (PMID26997249, PMID 25879830) including one in which we also reported delayed ovulation in women with low vitamin D (PMID 29337846). Similar to the animal studies, we recently found that high levels of 25-hydroxyvitamin D (25(OH)D), a biomarker of vitamin D status, were associated with a higher probability of becoming pregnant while low levels were associated with a lower probability of becoming pregnant (PMID: 31665286). Our research group collaborated with others at NIEHS and at NICHD to examine vitamin D deficiency and reproductive hormones; we found that estrogen was lower in vitamin D deficient women (PMID: 32068843). Vitamin D may interact with metals to alter absorption. We found some evidence for this in a clinical trial of vitamin D in Bangladesh (PMID: 33226277), but conflicting results in an observational cohort in the U.S. (PMID: 34022229). We plan to follow up on this study in our clinical trial.