Environment/Climate Change
Examining the relationship between high ambient temperatures and reproductive hormone levels in healthy premenopausal women: BioCycle study Kaniz Rabeya* Kaniz Rabeya Neil J. Perkins Lindsey M. Russo Pauline Mendola Timothy P. Canty Karen C. Schliep Nidhi Manchikanti Carrie J. Nobles
Background: Rising temperatures due to climate change have been linked to adverse reproductive health outcomes. While hormones play a critical role in reproductive health, the impact of high ambient temperature on hormone levels has been underexplored. We examined the relationship between ambient temperature and reproductive hormones in healthy premenopausal women.
Method: A prospective cohort study (BioCycle, 2005–2007) enrolled 250 regularly menstruating women (18-44 years) for two menstrual cycles from Buffalo, NY. Daily ambient temperature was averaged across the week (1-7 days) before menses, week (1-7 days) after menses, and 2nd week (8-14 days) after menses. Estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and progesterone (P4) were measured in serum at 8 time points during the menstrual cycle, including menstruation, mid-follicular phase, and LH/FSH surge. Generalized linear mixed models estimated the association between temperature and hormones overall, by season, and for temperature thresholds ≥ 22°C vs. 85th percentile) adjusting for season, age, and PM2.5.
Result: While we observed a trend of increasing E2 with increasing temperature, E2 decreased above higher temperature thresholds. For example, a 1°C increase in temperature one week before menses was associated with 0.26 pg/mL (95% CI, 0.04, 0.49) higher E2 at menstruation. Conversely, exposure to temperatures ≥ 22°C vs. < 22°C was associated with -13.74 pg/mL (95% CI, -25.66, -1.82) lower E2 at menstruation. The association between E2 and temperature was similar in the mid-follicular phase and LH/FSH surge. Additionally, we observed lower LH and FSH at LH/FSH surge and lower P4 at menses with higher temperatures.
Conclusion: Exposure to high ambient temperatures was associated with consistently lower E2 and modest reductions in LH, FSH, and P4, indicating reproductive hormones may play a role in the impact of high temperatures on women’s reproductive health.