Prenatal exposure to perfluoroalkyl and polyfluoroalkyl substances and birth outcomes: A longitudinal cohort with repeated measurements.

Background: Previous studies on perfluoroalkyl and polyfluoroalkyl substances (PFAS) showed inconsistent results when biological samples were collected in different time of pregnancy.
Objectives: To describe the change of PFAS concentration during pregnancy and to identify a sensitive window for adverse effects of PFAS on the fetus.
Methods: A total of 255 pregnant women were selected from the Shanghai Birth Cohort (SBC). We quantified 10 PFAS with high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) in maternal plasma at three trimesters and cord blood at delivery. Multiple linear regression analyses were used to analyze the association between PFAS and birth outcomes, including birth weight, birth length, and head circumference.
Results: The concentrations of most PFAS declined substantially during pregnancy. PFOS, PFNA, PFDA, PFUA and PFDoA were negatively related to birth length only in the first trimester. The coefficients and 95% confidence intervals (CI) of birth length change with a log-unit increase in PFOS, PFNA, PFDA, PFUS and PFDoA concentrations were -0.27 cm (-0.51, -0.02), -0.34 cm (-0.65, -0.03), -0.27 cm (-0.53, -0.01), -0.29 cm (-0.58, -0.01), and -0.54 cm (-1.00, -0.08), respectively. The effects were only observed for female fetuses. No association between PFAS and birth weight or head circumference was observed.
Conclusion: The concentrations of most PFAS in the maternal circulation declined during pregnancy. There were negative associations between several PFAS and birth length. The sensitive window of exposure appeared to be the first trimester. The association was stronger for female fetuses.
Competing Interests: Declaration of competing interest The authors declare no conflicts of interest.
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