Early pregnancy loss: Do Per- and polyfluoroalkyl substances matter?

Per- and poly-fluorinated substances (PFASs) with endocrine disrupting effect can efficiently transfer across the blood-follicle barrier. However, it is still controversial and attracting extensive public concern that whether PFASs can affect the human fertility potential. Therefore, we aimed to analyze the associations of women's exposure to PFASs with pregnancy loss, the relevant processes of fertilization, zygote implantation, and embryo development by using a prospective cohort study. The women undergoing in vitro fertilization-embryo transfer (IVF-ET) treatment were recruited in Beijing City (Beijing Center) and Yantai City (Yantai Center) in China during 2015-2017. A total of 305 women were recruited before the IVF-ET treatment. Twelve PFASs were measured in their serum samples collected in the day before the IVF-ET treatment, as well as in the human chorionic gonadotropin (hCG) day. The three IVF-ET outcomes were included, i.e. hCG test negative, clinical pregnancy failure (CPF), and preclinical spontaneous abortion. Nine serum PFASs had detection rate of >70% in Beijing and Yantai centers. The exposure patterns to PFASs between these two centers were overall different. For Beijing Center, we only found a positive association of perflurodecanoic acid (PFDA) with the risk of CPF [RR = 2.28 (95 %CI: 1.02-5.11)], but there is a reverse trend in Yantai Center with [RR = 0.45 (95 %CI: 0.23-0.85)]. However, the serum concentration of PFDA in Beijing Center was relatively lower than that of Yantai Center. Other significant associations of the detected PFASs with the IVF-ET outcomes, or with the relevant clinical processes, were not found. The multi-pollutant regression model of the Bayesian kernel machine regression suggested that there were no joint effects between various PFASs on the concerned outcomes. Overall, we suggest that most PFAS were not associated with early pregnancy loss at the current exposure levels. As for the PFDA, there may exist susceptibility of different populations.