The influence of fine particulate matter on the association between residential greenness and ovarian reserve

Abstract

Background: Natural vegetation, or greenness, is thought to improve health through its ability to buffer and reduce harmful environmental exposures as well as relieve stress, promote physical activity, restore attention, and increase social cohesion. In concert, these effects could help mitigate the detrimental effects of air pollution on reproductive aging in women.

Methods: Our analysis included 565 women attending the Massachusetts General Hospital Fertility Center (2004-2014) who had a measured antral follicle count (AFC), a marker of ovarian reserve. We calculated peak residential greenness in the year prior to AFC using 250 m² normalized difference vegetation index (NDVI) from the Terra and Aqua satellites operated by the United States National Aeronautics and Space Administration. Validated spatiotemporal models estimated daily residential exposure to particulate matter <2.5 μm (PM_2.5) for the 3 months prior to AFC. Poisson regression models with robust standard errors were used to estimate the association between peak greenness, average PM_2.5 exposure, and AFC adjusted for age, BMI, smoking status, education, year, and season.

Results: Women in our study had a mean age of 35.2 years with a standard deviation (SD) of 4.3 years (min: 20 years, max: 45 years). The peak residential NDVI ranged from 0.07 to 0.92 with a SD of 0.18. There was no statistically significant association between peak residential greenness and AFC; however, higher exposure to PM_2.5 was associated with lower AFC (-6.2% per 2 μg/m³ [1 SD increase] 95% CI -11.8, -0.3). There was a significant interaction between exposure to PM_2.5 and peak greenness on AFC (P-interaction: 0.03). Among women with an average PM_2.5 exposure of 7 μg/m³, a SD increase in residential peak greenness was associated with a 5.6% (95% CI -0.4, 12.0) higher AFC. Conversely, among women with a PM_2.5 exposure of 12 μg/m³, a SD increase in residential peak greenness was associated with a 5.8% (95% CI -13.1, 2.1) lower AFC.

Conclusions: Residing in an area with high levels of greenness may slow reproductive aging in women only when exposure to PM_2.5 is low.

Keywords: Air pollution; Built environment; Fertility; Greenness; Ovarian aging.

FIGURE 1.

Overview of study sample and exclusion criteria

Figure 2.

Slice plot displaying the interaction between peak greenness and average PM_2.5 exposures on adjusted mean AFC in the Environment and Reproductive Health Study, 2005–2014. Average PM_2.5 exposures of 7, 9, and 12 μg/m³ represent the 10^th, 50^th and 90^th percentiles in our population. The adjusted models account for age (continuous), BMI (continuous), smoking status (ever, never), education (<college, college, graduate school), year of AFC (continuous), season of AFC (Jan-Mar, Apr-Jun, Jul-Sept, Oct-Dec), average PM_2.5 exposure in 3 months prior to AFC (continuous), and a cross-product between peak NDVI exposure and average PM_2.5 exposure.

Figure 3.

Contour and scatter plot displaying the interaction between PM_2.5 and peak greenness exposures on adjusted mean AFCs in the Environment and Reproductive Health Study, 2005–2014. Adjusted models account for age (continuous), BMI (continuous), smoking status (ever, never), education (2.5 exposure in 3 months prior to AFC (continuous), and a cross-product between peak NDVI exposure and average PM_2.5 exposure.