Exposure to nitrogen dioxide, particulate matter increases miscarriage risk

Key takeaways:

• Nitrogen dioxide exposure near time of conception was tied to more than double the miscarriage risk vs. less exposure.
• In addition, 1-day peak particulate matter exposure was tied to increased miscarriage risk.

NEW ORLEANS — Exposure to air pollution around the time of conception was linked to an increased risk for miscarriage compared with less exposure, according to study results presented at the ASRM Scientific Congress & Expo.

However, in fully adjusted models, researchers noted that these associations failed to remain significant. These findings add to the current human studies available that are limited by infertile populations or small sample sizes and more research is needed, according to the study abstract.

Anne Marie Z. Jukic, PhD, investigator in the Epidemiology Branch/Fertility and Reproductive Health Group at the National Institute of Environmental Health Sciences, and colleagues evaluated data from 446 women from the Time to Conceive (TTC) prospective, time-to-pregnancy cohort study from 2008 to 2016 in North Carolina. All women were aged 30 to 44 years with no infertility history and were trying to conceive for more than 3 months at recruitment. All participants reported each menses and any positive pregnancy results during the study.

Based on geocoded residential addresses for participants, researchers obtained ambient concentrations of particulate matter less than 2.5 µm in diameter (PM_2.5), particulate matter less than 10 µm in diameter (PM₁₀) and levels of ozone, carbon monoxide, nitric oxide, nitrogen dioxide and sulfur dioxide. These data came from the U.S. Environmental Protection Agency’s Fused Air Quality Surface Using Downscaling (FAQSD) files and the Community Multiscale Air Quality (CMAQ) modeling system. Researchers assessed six exposure windows and estimated the daily average and peak concentrations of each pollutant and its association with likelihood of miscarriage.

Overall, 101 pregnancy losses occurred during the study period. Researchers observed the most consistent associations between miscarriage and increasing nitrogen dioxide exposure. All estimates were greater than 1 in fully adjusted models and across exposure windows. During the follicular phase, higher levels of nitrogen dioxide exposure were linked to more than two times the risk for miscarriage (RR = 2.3; 95% CI, 1-5.27).

In addition, an increased miscarriage risk was associated with 1-day peak PM₁₀ during the luteal placental shift window, between 7 and 9 weeks gestation (RR = 1.4; 95% CI, 1.04-1.89).

“We suggest that miscarriage be examined in larger studies, perhaps in a pooled study of multiple cohorts or an analysis to leverage a larger sample of pregnancy losses,” Jukic said.

Reference:

• Jukic AMZ, et al. J Fert Steril. 2023;doi:10.1016/j.fertnstert.2023.08.849.