Abstract: Objective: This study aims to investigate the critical window(s) of exposure to PM_2.5 during pregnancy on offspring neurodevelopmental impairments by reviewing existing literature and conducting a meta-analysis, in order to provide a theoretical basis for individual-level protection against PM_2.5 exposure during pregnancy. Methods: We searched three English-language databases—PubMed, Elsevier's ScienceDirect, and Web of Science—for all literature on the associations between prenatal PM_2.5 exposure and offspring neurodevelopmental impairments. Studies reporting odds ratio (OR) values for exposure during the first, second, and third trimesters, according to predetermined criteria, were selected for meta-analysis. Results: A total of 14 studies meet inclusion criteria after excluding duplicates and non-qualifying studies. Meta-analysis of ORs revealed significant associations between PM_2.5 exposure during all three trimesters and offspring neurodevelopmental impairments. The strongest association was observed during the second trimester (OR = 1.11, 95% CI: 1.04-1.18), followed by the first trimester (OR = 1.10, 95% CI: 1.04-1.15) and the third trimester (OR = 1.09, 95% CI: 1.02-1.16). Conclusion: PM_2.5 exposure during all gestational periods could significantly increase the risks of neurodevelopmental impairments in offspring, with the strongest association observed during the second trimester. This period warrants targeted protective measurements for prenatal PM_2.5 exposure.