Pesticide exposure and spontaneous abortion risk: A comprehensive systematic review and meta-analysis

Backgrounds and aim

Exposure to pesticides has been proposed as a potential contributor to adverse pregnancy outcomes, possibly through the induction of inflammation, oxidative stress, and disruption of endocrine functions. Nevertheless, the definitive link between prenatal pesticide exposure and the risk of Spontaneous Abortion (SAB) remains uncertain. The objective of this systematic review is to explore and analyze the existing evidence regarding the link between pesticide exposure and the risk of SAB.

Methods

A comprehensive systematic literature search was carried out on PubMed, Web of Science, and Scopus from their inception until February 2024 to identify relevant studies exploring the potential link between pesticide exposure and SAB. The frequency of SAB events and the total number of patients in each group were used to calculate the Relative Risk (RR) using the Mantel-Haenszel random-effects model. Heterogeneity among the studies was evaluated by visually inspecting the forest plot and performing the Chi-square test and I2 tests. We also used RevMan version 5.4 for Windows for the analysis. We also used the NIH tool to assess the quality of the included studies.

Results

The initial database search yielded 2121 results, with 1525 articles remaining after removing duplicates. After screening, 29 articles were eligible for full-text review, and 18 studies (Four case-control, eleven cohorts, three cross-sectional) were included in the meta-analysis, comprising 439,097 participants. All included studies evaluated the primary outcome, SAB. Most of the included studies were cross-sectional in design, and pesticide exposure was primarily assessed through questionnaires administered to patients. We found that most of our observational studies, precisely 12 out of the total, were deemed fair quality. Four studies were rated poor quality, while only two received a good quality rating. The analysis demonstrated a significant 41 % increase in SAB risk among pregnant women exposed to pesticides compared to pregnant women without exposure to pesticides (RR= 1.41, 95 % CI; [1.10, 1.80], P= 0.006).

Conclusion

Our systematic review and meta-analysis revealed a significant 41 % increase in the risk of SAB among pregnant women exposed to pesticides. However, it is essential to acknowledge the limitations of the current evidence: potential publication bias and the inability to establish causality. Moving forward, future research should focus on longitudinal studies, mechanistic insights, and risk reduction strategies. In summary, our findings underscore the urgency of public health measures to protect maternal and fetal health in pesticide-exposed areas. Rigorous research and preventive strategies are crucial to mitigate adverse outcomes.