Association study of umbilical cord serum per- and polyfluoroalkyl substances (PFAS) exposure with birth outcomes: A meta-analysis.

BACKGROUND It has been reported that per- and polyfluoroalkyl substances (PFAS) in cord serum are closely associated with birth outcomes. However, the associations vary inconsistently across different studies. To summarize the relationships between cord serum PFAS and birth outcomes, a meta-analysis was performed.

METHODS The characteristics of the studies, β values and 95 % confidence intervals were extracted. A random effects model or a fixed effects model was selected for analysis based on the I2 value. Subgroup analyses were applied to explore the sources of heterogeneity.

RESULTS We included 22 eligible studies in this meta-analysis. Perfluorooctanoic acid (PFOA) in cord serum was positively related to gestational age (β = 0.10; 95 % CI: 0.00, 0.19; P < 0.05). Cord serum perfluorononanoic acid (PFNA) was positively associated with birth length and head circumference, with corresponding values of 0.18 (95 % CI: 0.10, 0.26; P < 0.05) and 0.07 (95 %CI: 0.01, 0.14; P < 0.05), respectively. Cord serum perfluoroundecanoic acid (PFDA) was significantly associated with birth length (β = 0.15; 95 % CI: 0.04, 0.27; P < 0.05). Based on the subgroup analysis, it was found that the associations between PFOA exposure and birth weight, between PFNA and birth length, and between PFOS and head circumference were more pronounced at high dose levels.

CONCLUSIONS This meta-analysis demonstrates that PFAS concentrations in cord serum are significantly associated with gestational age, as well as neonatal head circumference and birth length. However, whether these findings might translate into an elevated risk of abnormal birth outcomes associated with PFAS concentration in cord serum warrants further investigation.