Associations between Ambient Air Pollution Exposure and Menstrual Cycle Irregularity in Premenopausal Women.

PURPOSE: This study investigates the associations between various air pollutants and menstrual cycle irregularity. MATERIALS AND METHODS: Data for premenopausal women were obtained from the Korea National Health and Nutrition Examination Survey (n=4478). We evaluated the associations of moving averages of five air pollutants over 90, 120, 150, 180, and 365 days with short-interval (menstruation occurring at least once every 3 months) and long-interval (menstruation skipped for ≥ 3 months) menstrual cycle irregularity using multinomial logistic regression models. The joint effects of air pollution mixtures were explored using the quantile g-computation method. RESULTS: Interquartile range increases in moving averages of nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) over 90, 120, 150, and 180 days were associated with short-interval menstrual cycle irregularity [e.g., odds ratio (OR)=1.24, 95% confidence interval (CI): 1.03, 1.50 for NO₂ over 120 days; OR=1.07, 95% CI: 1.03, 1.12 for SO₂ over 150 days]. Each quintile increase in air pollution mixture (NO₂ over 120 days and SO₂ over 150 days) was also associated with short-interval menstrual cycle irregularity (OR=1.07, 95% CI: 1.00, 1.14). CONCLUSION: Our results indicate associations between various exposure indices of NO₂ and SO₂ and short-interval menstrual cycle irregularity in a representative sample of Korean premenopausal women. This research represents one of the first investigations on this issue; therefore, further longitudinal studies are warranted to confirm these findings.