Transplacental Transfer of Per- and Polyfluoroalkyl Substances (PFASs): Differences between Preterm and Full-Term Deliveries and Associations with Placental Transporter mRNA Expression

Abstract

Previous studies demonstrated that per- and polyfluoroalkyl substances (PFASs) can cross human placental barrier. However, their transplacental transfer efficiencies (TTEs) have not been investigated in preterm delivery and the role of placental transport proteins has rarely been explored. Our study hypothesized that the TTEs of PFASs could differ between preterm and full-term delivery and some placental transporters could be involved in active maternofetal PFAS transfer. In the present study, the median TTEs of 16 individual PFAS chemicals or isomers were determined to be 0.23 – 1.72 in matched maternal-cord serum pairs with preterm delivery (N = 86), significantly lower than those (0.35 – 2.26) determined in full-term delivery (N = 187). Significant associations were determined between the TTEs of several PFASs and the mRNA expression levels of selected transporters located on the brush border membrane. The association patterns also differed significantly between preterm and full-term delivery and exhibited a chemical-specific manner. For example, the expression of MRP2 exhibited significantly positive associations with the TTEs of linear and branched PFOS isomers in full-term delivery, but negative, non-significant associations were observed in preterm delivery. This is the first study to compare transplacental transfer of PFASs between preterm and full-term delivery and indicate that some placental transport proteins could be involved in active transmission. The mechanisms underlying cross-placental transfer of PFASs require further investigations in order to better elucidate their risks to fetal health and birth outcomes.