Does air pollution affect menstrual regularity?
A study recently published in Human Reproduction found that air pollution is linked to irregular menstrual cycles. The research focused on exposure to air pollution among teenage girls (ages 14-18) and found an association between the exposure and a slightly increased chance of menstrual irregularity along with longer time to attain regularity.
The researchers used a cross-sectional study of 34,832 of the original 116,430 women enrolled (29.91%) in 1989 from Nurses’ Health Study II (NHSII). Looking at the perimenarchal exposure to total suspended particulate (TSP) in air during the participants’ years of high school attendance, the researchers compared exposure levels with time to menstrual cycle regularity, as self-reported by the participants. They created three case definitions including high school menstrual irregularity and androgen excess.
In multivariable adjusted models, the authors observed that for every 45 mg/m3 increase in average high school TSP, the odds of moderate, persistent, and persistent with androgen excess irregularity phenotypes increased by 1.08 (1.03 – 1.14), 1.08 (1.02 – 1.15) and 1.10 (0.98 – 1.25), respectively. TSP was also associated with longer time to cycle regularity, with stronger results seen in women who were older at menarche and also among participants living in the Northeast or the West.
The researchers noted a few limitations in the study. The participant responses may have been susceptible to recall bias since the outcomes of menstrual regularity and time to cycle regularity were retrospectively assessed. They also noted potential for selection bias since women participating in the study had to live until 2011 to provide addresses to the researchers. The researchers noted that while this research aligns with existing literature on air pollution and reproductive tract diseases, more study is needed to determine the wider implications of the findings.