P4.044: Association of Prenatal Exposure to Poly-and Perfluoroalkyl Substances (PFAS) With Birth Outcomes Among Michigan Mothers and Newborns

Background: The early-life period is particularly vulnerable to the influences of environmental exposures. Poly- and perfluoroalkyl substances (PFAS) are persistent bioaccumulative chemicals that can cross the placental barrier and have been associated with increased risk of adverse birth outcomes. Despite phase-out of legacy PFAS, these chemicals remain ubiquitously present in the environment and are still detected in the majority of the US population. Newer fluorinated chemicals are continuously being introduced as legacy PFAS substitutes; however, their exposure levels and health risks have not been well characterized. We measured serum legacy and emerging PFAS concentrations in pregnant women in Michigan, a state with well-known PFAS contamination, and assessed relationships between PFAS and birth outcomes.

Methods: Our analytic sample included 317 women enrolled in one of two prospective birth cohorts in Michigan as part of the Child Health Advances from Research with Mothers (CHARM) alliance. Concentrations of 13 legacy PFAS were measured in the earliest available pregnancy serum for all participants, with an additional 34 emerging PFAS measured in a subset of participants. Adjusted linear regression models were used to estimate the association between prenatal PFAS concentrations with gestational age and birth weight for gestational age z-scores.

Results: Twelve PFAS were detected in >70% of participants, including the replacement PFAS 6:2 FTS and PFHpS. Legacy PFAS - PFOA, PFOS, PFHxS, and PFNA - were detected in 95-100% of participants. For a 1-unit higher log-normalized concentration of PFOA and PFUnDA, we observed lower birthweight-for-gestational-age z-scores of β = -0.16 [95% CI: -0.29, -0.03] and β = -0.16 [95% CI: -0.29, -0.04], respectively. Sex-stratified analyses revealed significant associations between increasing concentrations of multiple PFAS and lower birthweight-for-gestational-age z-scores among girls (PFOA: β = -0.20 [95% CI: -0.39, -0.01], PFNA: β = -0.22 [95% CI: -0.40, -0.004], PFDA: β = -0.31[95% CI: -0.50, -0.06], PFUnDA: β = -0.21 [95% CI: -0.40, -0.03]) but no significant associations among boys.

Conclusion: Pregnant women in Michigan are exposed to legacy and emerging PFAS. Early pregnancy exposure to select PFAS compounds is associated with smaller size at birth, with more pronounced associations in girls. Future studies are needed to determine the long-term impact on child growth and development and potential interventions to mitigate prenatal exposures.