Association between maternal exposure to polycyclic aromatic hydrocarbons and birth anthropometric outcomes: A systematic review and meta-analysis

Background: Previous research has proposed that exposure to polycyclic aromatic hydrocarbons (PAHs) during pregnancy could potentially lead to a higher risk of adverse birth anthropometric outcomes. However, the current evidence on this connection remains inconclusive, as various studies have presented conflicting results. Objective: This systematic review and meta-analysis seeks to synthesize the available research on the potential link between maternal PAHs exposure and birth anthropometric outcomes. Methods: A comprehensive search of Scopus, PubMed/MEDLINE, Web of Science, and the Cochrane Library up to July 1, 2024, was conducted to identify studies investigating the impact of maternal PAHs exposure during pregnancy on birth anthropometric measures, including small gestational age (SGA), low birth weight (LBW), birth weight (BW), birth length (BL), birth head circumference (BHC), and birth chest circumference (BCC). Quality assessment was performed using the Newcastle-Ottawa Scale (NOS) and the GRADE framework, and a random-effects meta-analysis was conducted to consolidate association estimates. Results: Out of 5499 articles initially screened, 27 studies were included in the review. The meta-analysis revealed no significant association between maternal PAHs exposure and LBW (OR: 1.02, 95 % CI: 0.96-1.08), with moderate heterogeneity (I-2: 25.8 %, P=0.37). Notably, PAHs exposure was significantly associated with BW (beta: -9.79 g, 95 % CI: -16.71 to -2.87), along with high heterogeneity (I-2: 99.9 %, P<0.001), and shorter BL (beta: -0.04 cm, 95 % CI: -0.07 to -0.01), also with high heterogeneity (I-2: 84.3 %, P<0.001). Additionally, a borderline significant decrease in BHC was observed (beta: -0.01 cm, 95 % CI: -0.02 to -0.00) with no significant heterogeneity among studies. The results SGA were inconsistent across the studies. Conclusion: Maternal exposure to PAHs was associated with adverse birth anthropometric outcomes, particularly lower BW and BL. The borderline significant reduction in BHC suggests a potential impact worth further investigation, although this finding remains inconclusive and not yet actionable. Results for SGA varied significantly among studies, underscoring the complexity of these associations. Collectively, these findings highlight the necessity for additional research to elucidate the effects of specific PAH metabolites on birth anthropometric outcomes and to explore potential interventions aimed at mitigating the identified risks.