Environmental influences on fertility and reproductive health

National Institute Of Environmental Health Sciences

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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 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 previously published three studies that have reported associations between low 25(OH)D and long or irregular menstrual cycles, delayed ovulation, and lower probability of conception. In the U.S., levels of vitamin D are lower in reproductive-aged women compared with other age groups and are particularly low in non-Hispanic Black women (PMID: 39408379). We previously reported that chronic inflammation did not underlie our observed association of vitamin D with conception although inflammation was associated with menstrual cycle length, ovulation timing, and ovarian reserve biomarkers (PMID: 39623697). We recently found that certain air pollutants increased miscarriage risk among women with low vitamin D but not among women with high vitamin D (PMID: 40447021). Similarly, higher vitamin D has been inconsistently associated with lower levels of metals, and to better inform future research, we published a review of the biological pathways linking vitamin D and metals. Vitamin D’s interactions with other environmental exposures should be further investigated. We published a literature review summarizing how the menstrual cycle functions as a vital sign and its importance for women’s health (PMID: 39906529). We explored trends in senor-based metrics during and after pregnancy (PMID: 39296604) and used sensor data to identify ovulation and menses start day (PMID: 39881571).