Maternal exposure to fine particulate matter and pregnancy outcomes in women undergoing in vitro fertilization: A multicenter retrospective study

Few large-scale studies have systematically examined the effects of maternal exposure to fine particulate matter (PM_2.5) on live birth in women undergoing <i>in vitro</i> fertilization (IVF). This study aimed to investigate the associations between ambient PM_2.5 exposure and live birth in women treated with IVF, and determine critical periods, key failure events, and vulnerable populations affected by such exposure. We included 58,637 patients from six reproductive centers in China between 2016 and 2021. We defined six exposure windows and adopted logistic regression with random-effect models to investigate the associations between PM_2.5 exposure and live birth. We further categorized live birth failure as implantation failure, biochemical pregnancy loss, and miscarriage, to determine at which stage PM_2.5 exposure caused the live birth failure. Subgroup analyses were conducted by female age, ovarian response, embryo quality, and transplantation protocol. For each 10 ​μg/m³ increase in PM_2.5 concentration during follicle growth phase, preantral-antral follicle phase, and antral-mature follicle phase, the odds ratios for live birth were 0.966 [95% confidence interval (CI): 0.938, 0.995], 0.967 (0.939, 0.996), and 0.978 (0.958, 0.998), respectively. PM_2.5 during these stages was significantly associated only with an increased likelihood of implantation failure, highlighting adverse impact of ambient PM_2.5 on early pregnancy outcome. In addition, we observed relatively stronger associations in women with poor ovarian response, compromised embryo quality, and those undergoing fresh or double embryo transfers. This large-scale population-based study demonstrated the detrimental effects of high PM_2.5 exposure for IVF women, shedding light on clinical and public health practices.