Prenatal Perfluorooctanoic Acid (PFOA) Exposure Significantly Decreases in utero Fetal Head Circumference and Biparietal Diameter Growth Among Women Reporting Higher Levels of Perceived Stress

Background and Aim Perfluoroalkyl Substances (PFAS) are ubiquitous synthetic chemicals with long half-lives and are known to cross the placenta during pregnancy. We examined the influence of maternal PFAS levels on in utero fetal growth trajectories and assessed whether maternal stress modified these associations. Methods Blood serum concentrations of five PFAS (PFOS, PFHxS, PFNA, PFOA, PFDA) were measured in 335 prenatal specimens (mean gestational age (GA): 21±9 weeks) in the MADRES cohort. Fetal growth outcomes were abstracted from ultrasound medical records and head circumference (HC), abdominal circumference (AC), biparietal diameter (BPD), and femur length (FL) were also measured at the 3rd trimester study visit (N=833 scans, GA range 10-42 weeks, mean 2.4 scans/participant). Adjusted linear mixed models with a GA quadratic growth curve were used for each PFAS exposure and growth outcome. PFOS and PFHxS were modeled continuously (100% sample detection), while PFOA, PFNA, and PFDA were modeled categorically (57%-70% sample detection). Scores on the Perceived Stress Scale (PSS) measured in pregnancy were dichotomized at the median (<13 vs. ≥ 13) in stratified models. Results Participants were on average 29±6 years old and predominately Hispanic (76%). Median serum concentrations of PFOS, PFHxS, PFNA, PFOA and PFDA were 1.34, 1.10, 0.07, 0.12, and 0.04 ng/mL, respectively. Participants with detected PFOA concentrations had fetuses with –2.5 mm (95% CI -4.2, -0.8) smaller HC and –0.7 mm (95% CI -1.3, -0.2) smaller BPD on average than those without detected PFOA concentrations. In models stratified by PSS level, the effects of PFOA on fetal growth parameters were stronger and only significant in participants with higher stress levels (HC: β= -3.5, 95% CI -5.8, -1.4; BPD: β = -0.8, 95% CI -1.6, -1.1). Conclusions Prenatal PFOA exposure adversely impacted fetal head biometric parameters in participants experiencing higher stress during pregnancy. Keywords PFAS; Fetal Growth; Stress