Atmospheric pollution could disrupt menstrual cycle function

Scientists at the French institute for medical research Inserm have observed a potential link between exposure to particulate matter and a longer follicular phase in menstrual cycles.

In January 2018, an American study conducted by researchers at Boston University in the United States showed that air pollution could have an impact on the menstrual cycle. Now new research by Inserm scientists has provided further evidence of this phenomenon.

Rémy Slama of the Grenoble University Institute of Advanced Biosciences supervised the research which has been published in the review Environmental Pollution. The study recruited 184 women not using hormonal contraception. The participants agreed to collect urine samples at least every other day to allow the researchers evaluate their exposure to pollution over the course of a 30-day period preceding a menstrual cycle.

Environmental levels of particulate matter and nitrogen dioxide pollution were established on the basis of the home addresses of participants and data from permanent monitoring stations.

A longer follicular phase

Scientists observed a correlation between an increased concentration of particulate matter in the air and the duration of the preovulatory phase of the menstrual cycle, called the “follicular phase” (as opposed to the luteal phase, which corresponds to post-ovulation). The hypothalamic-pituitary-ovarian axis, the brain’s transmission chain of hormonal information between the hypothalamus, the pituitary gland (gland below the hypothalamus) and the ovaries, ensures the proper regulation of these phases.

The study suggests that the follicular phase tends to increase with pollution levels. Indeed, each 10 µg/m3 increase in particulate matter concentration in air over a 30-day period before the cycle was associated with an increase in the duration of the follicular phase of about 0.7 days, or just under one day. On the other hand, no net change in the duration of the luteal phase or the total duration of the cycle was observed.

“These results are consistent with the more fundamental data suggesting that air pollution can disrupt the axis that controls the menstrual cycle and stress hormones such as cortisol, which can also influence it. It will probably take some time to refute or confirm this new hypothesis with larger population samples, given the cost and effort involved in such studies,” explained Rémy Slama in a press release published on the Inserm website.

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