Association between maternal exposure to perfluoroalkyl and polyfluoroalkyl substances and risks of adverse pregnancy outcomes: A systematic review and meta-analysis.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs), a class of persistent endocrine-disrupting chemicals, are widely used in consumer products due to their unique amphiphilic properties. Previous epidemiological studies suggest association of maternal PFASs exposure and adverse pregnancy outcomes, while evidences about the association are inconsistent. The aim of this systematic review and meta-analysis is to assess the relationship of maternal PFASs exposure and adverse pregnancy outcomes. Twenty-one relevant studies were identified from three databases before 2020. The quality, heterogeneity and possibility of publication bias of included studies were evaluated by Newcastle-Ottawa Scale, Q-statistic and Begg's test, respectively. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were obtained by means of random-effects meta-analysis models. Meta-analysis results revealed that maternal exposure to perfluorooctane sulfonic acid (PFOS) may have a positive association with preterm birth (OR = 1.20, 95% CI: 1.04, 1.38). The pooled estimates also showed limited evidence of association between maternal perfluorononanoic acid (PFNA) exposure and miscarriage (OR = 1.48, 95% CI: 0.92, 2.38) with obvious heterogeneity (I2 = 93.9, p < 0.01). However, no such significant associations were found between the other PFASs and miscarriage, stillbirth and preterm birth. In addition, the subgroup analyses showed that studies on the relationship of maternal PFASs exposure and miscarriage were mainly contributed by developed countries. The meta-analysis results indicated maternal exposure to PFOS can increase the risk of preterm birth. The results of the included studies are inconsistent and the effects of PFASs on human health are complex. Further studies with enough samples are required to verify these findings.