Outdoor air pollution and diminished ovarian reserve among infertile Korean women

Abstract

Background: Mounting evidence implicates an association between ambient air pollution and impaired reproductive potential of human. Our study aimed to assess the association between air pollution and ovarian reserve in young, infertile women.

Methods: Our study included 2276 Korean women who attended a single fertility center in 2016-2018. Women's exposure to air pollution was assessed using concentrations of particulate matter (PM₁₀ and PM_2.5), nitrogen dioxide (NO₂), carbon monoxide (CO), sulfur dioxide (SO₂), and ozone (O₃) that had been collected at 269 air quality monitoring sites. Exposure estimates were computed for 1, 3, 6, and 12 months prior to the ovarian reserve tests. Anti-Müllerian hormone (AMH) ratio (defined as an observed-to-expected AMH based on age) and low AMH (defined as < 0.5 ng/mL) were employed as indicators of ovarian reserve. We included a clustering effect of 177 districts in generalized estimating equations approach. A secondary analysis was conducted restricting the analyses to Seoul residents to examine the association in highly urbanized setting.

Results: The mean age was 36.6 ± 4.2 years and AMH level was 3.3 ± 3.1 ng/mL in the study population. Average AMH ratio was 0.8 ± 0.7 and low AMH was observed in 10.3% of women (n=235). The average concentration of six air pollutants was not different between the normal ovarian reserve and low AMH groups for all averaging periods. In multivariable models, an interquartile range (IQR)-increase in 1 month-average PM₁₀ was associated with decrease in AMH ratio among total population (β= -0.06, 95% confidence interval: -0.11, 0.00). When we restrict our analysis to those living in Seoul, IQR-increases in 1 and 12 month-average PM_2.5 were associated with 3% (95% CI: -0.07, 0.00) and 10% (95% CI: -0.18, -0.01) decrease in AMH ratio. The ORs per IQR increase in the six air pollutants were close to null in total population and Seoul residents.

Conclusions: In a cohort of infertile Korean women, there was a suggestive evidence of the negative association between ambient PM concentration and ovarian reserve, highlighting the potential adverse impact of air pollution on women's fertility.

Keywords: Air pollution; Anti-Müllerian hormone; Fertility; Ovarian reserve.

Fig. 1

Association between ovarian reserve and air pollutant concentrations. a A 1-month average PM₁₀ and the AMH ratio in total population and b a 1-month average PM_2.5 and the AMH ratio in Seoul residents. Generalized additive models with non-parametric smoothing splines were used. Interrupted lines indicate 95% confidence intervals of estimates.