Environment/Climate Change
Ambient temperature during susceptible windows of spermatogenesis and impact on hCG+ pregnancy in an infertility treatment population Lindsey M. Russo* Lindsey M. Russo J. Richard Pilsner Timothy P. Canty Pauline Mendola Kaniz Rabeya Karen S. Schliep May Shaaban Akanksha Singh Allison M. Ring Rachael Hemmert Neil J. Perkins James A. VanDerslice C. Matthew Peterson Erica Johnstone Carrie Nobles
Background: Male preconception exposure to temperature remains a critically under-addressed area of family planning. Animal studies have found spermatogenesis susceptible to heat stress; therefore, we examined ambient temperature and hCG+ pregnancy in the Folic Acid and Zinc Supplementation Trial (2013-2018) among couples seeking infertility treatment in Salt Lake City.
Methods: In the FAZST Trial (n=2,015 men), we evaluated four susceptible windows of ambient air pollution exposure during spermatogenesis (mitosis, meiosis I-II, spermiogenesis, spermiation) for semen samples provided during couple-level intrauterine insemination (IUI, n=505 couples and 1,223 cycles) or in vitro fertilization (IVF, n=221 couples and 280 cycles) treatment cycles over nine months of follow-up. Daily ambient temperature was abstracted from weather monitoring stations for Salt Lake City and averaged across each susceptibility window. Treatment-cycle probability of pregnancy was assessed for IUI and IVF cycles separately using generalized linear mixed models adjusted for fine particulate matter, ozone, age, and income, as well as interaction with warm (Apr – Sept) versus cold season (Oct – Mar).
Results: Overall, there were 133 (10.9%) IUI and 171 IVF hCG+ pregnancies (61.1%). For a 2° C increase in average ambient temperature in the warm season, we observed no clear association in models adjusted for age, income, and fine particulate matter [e.g., RR: 1.01, 95% CI: 0.95, 1.07 during meiosis]. Upon addition of ozone, a seasonal confounder, we observed a higher likelihood of IUI pregnancy during mitosis and meiosis [e.g., RR: 1.13, 95% CI: 1.03, 1.23 for meiosis]. We observed minimal impacts among IVF participants. No associations were observed during the cold season.
Conclusion: Overall, we observed few associations, but found an unexpected association when adjusting for ozone, which may suggest potential mediation or other complexity.