Time-Varying Exposure to Fine Particulate Matter and Black Carbon and Outcomes of In Vitro Fertilization

Abstract

Background/Aim: Air pollution has been linked to decreased fertility yet the specific mechanisms and windows of susceptibility remain unclear. We examined the association between time-varying exposure to fine particular matter (PM2.5) and black carbon (BC) on in vitro fertilization (IVF) outcomes.Methods: We included 356 women (537 cycles) for the PM2.5 analysis (2005-2016) and 234 women (343 cycles) for the BC analysis (2005-2011) enrolled in a prospective cohort study of couples undergoing a fresh IVF cycle in New England. We used spatiotemporal models to estimate daily PM2.5 and BC exposures (based on residential address) throughout the IVF cycle. Multivariable discrete time Cox proportional hazards models with 3 time periods (cycle initiation to embryo transfer (ET), ET to implantation, implantation to live birth) were used to estimate odds ratios (OR) and 95% confidence intervals (CI) of failing at IVF. Time-dependent interactions between exposures and IVF time windows were used to identify vulnerable periods.Results: An interquartile range (IQR) increase in PM2.5 (3 µg/m3) and BC (0.2 µg/m3) throughout the IVF cycle was associated with a non-significant, elevated odds of failing at IVF prior to live birth (OR=1.15, 95% CI 0.96, 1.38 for PM2.5 and OR=1.25, 95% CI 0.87, 1.78 for BC). The effect of PM2.5 and BC exposure on IVF failure was strongest during the earliest windows of IVF. Specifically, an IQR increase in PM2.5 and BC exposure was associated with 1.30 (95% CI 1.01, 1.67) and 1.55 (95% CI 1.15, 2.10) times the odds of failing prior to ET, 1.07 (95% CI 0.82, 1.39) and 1.18 (0.77, 1.80) times the odds of failing between ET and implantation, and 1.05 (0.59, 1.88) and 0.82 (0.43, 1.59) times the odds of failing between implantation and live birth.Conclusion: Increased exposure to PM2.5 and BC during ovarian stimulation is associated with higher odds of IVF failure prior to ET. Acute exposure to PM2.5 and BC may have adverse effects on oocyte development.