Review Article Copyright © All rights are reserved by Raouf Roshdy Ambient Fine Particulate Matter and Assisted Reproduction: A Narrative Review of Gamete, Implantation and Fetal Evidence

Background: Fine Particulate Matter (PM2.5) is a candidate modifiable risk factor in Assisted Reproductive Technology (ART), but published estimates disagree on size, timing and even direction. Methods: Narrative review. We searched PubMed on 27 October 2026 for human and experimental studies linking PM2.5 and related air-pollution metrics to ovarian reserve, gametes, implantation, early loss, placental function, fetal outcomes and mitigation. Records were screened by title and abstract; reported estimates were taken from abstracts. No formal risk-of-bias scoring was done. Findings: In a single-clinic cohort of 3659 frozen embryo transfers, highest-quartile PM2.5 in the three months before oocyte retrieval carried 34% lower odds of live birth (OR 0.66, 95% CI 0.47-0.92) than the lowest quartile. A meta-analysis of five studies (about 282,000 participants) found a 6% lower probability of live birth per 10 µg/m³ of fine particulate matter in the year before retrieval (RR 0.94, 95% CI 0.92-0.97). A US registry analysis of 253,528 fresh cycles found no association between PM2.5 and any reproductive outcome. Cohorts of 5354 and 29,610 ART patients linked particulate exposure to lower antral follicle count. In 21,851 US semen samples, PM2.5 was associated with sperm DNA fragmentation, with a non-linear pattern peaking near 11 µg/m³. Cell and rodent studies show trophoblast, granulosa-cell and follicle injury, but they do not establish human effect sizes. Evidence for fetal harm is modest for preterm birth (pooled OR 1.07 for whole-pregnancy PM2.5 in China) and mixed for neurodevelopment. Air-purifier trials show limited benefits. Conclusion: The association between PM2.5 and poorer ART outcomes is plausible and repeatedly observed, but the evidence is observational, heterogeneous and partly null. [Inferen