Can atmospheric pollutants influence menstrual cycle function?

A few experimental studies suggest that atmospheric pollutants could affect the endocrine system, and in particular stress hormones and the hypothalamic-hypophyseal-ovarian axis, which could in turn influence menstrual cycle function. We aimed to study the possible short-term effects of atmospheric pollutants on the length of the follicular and luteal phases and on the duration of the menstrual cycle in humans. To do so, from a nation-wide study on couples' fecundity, we recruited 184 women not using contraception who collected urine samples at least every other day during one menstrual cycle, from which a progesterone metabolite was assayed, allowing estimation of the duration of the follicular and luteal phases of the cycle. Atmospheric pollution (nitrogen dioxide and particulate matter with an aerodynamical diameter below 10 µm, PM10) levels were estimated from a dispersion model with a 1-km resolution combined with permanent monitoring stations measurements, allowing to estimate exposures in the 30-day, 1-10 and 11-30-day periods before the start of the menstrual cycle. Regression models allowed to quantify the change in cycle duration associated with atmospheric pollutants and adjusted for potential confounders. Follicular phase duration increased on average by 0.7 day (95% confidence interval, CI, 0.2; 1.3) for each increase by 10 µg/m3 in NO2 concentration averaged over the 30 days before the cycle and by 1.6 day (95% CI, 0.3; 2.9) for each increase by 10 µg/m3 in PM10. There was no strong evidence of associations of exposures in this time window with luteal phase or with total menstrual cycle durations (p > 0.2). Exposures in the 1-10 day period before the cycle start were also associated with increased follicular phase duration. This study is one of the first prospective studies to suggest short-term alterations in follicular phase duration following atmospheric pollutants exposure.

Estimation of the frequency of involuntary infertility on a nation-wide basis.

BACKGROUND: Assessing couple fecundity on a nation-wide basis without excluding couples who eventually remain infertile is challenging. Our aim was to describe couple fecundity (in terms of frequency of involuntary infertility) among the general population living in France. METHODS: We used a current-duration design. A random sample of 64 262 households was selected in 2007-2008, allowing us to identify 15 810 women aged 18-44 years. Eligible women (n= 1089) were those having regular sexual intercourse with a male partner, not using any method of contraception and not having delivered in the previous 3 months. These women reported information on the current duration of unprotected intercourse (CDUI, the time elapsed between the start of the period of unprotected intercourse and the time of inclusion in the study). The CDUI distribution was used to estimate the frequency of involuntary infertility, using a newly developed statistical technique that does not require couples to be followed up until the end of the period of unprotected intercourse. RESULTS: CDUI was defined for 867 women. An estimated 46% of couples had no detected pregnancy conceived during the first 6 months of unprotected intercourse [95% confidence interval (CI), 36-56%]. The proportions of couples with no detected pregnancy within 12 and 24 months were 24% (19-30%) and 11% (8-14%), respectively. CONCLUSIONS: These results constitute one of the few descriptions of the fecundity of a nation-wide representative sample of couples from the general population, not limited to couples who eventually conceived or to those resorting to medical help.