Particulate matter (PM2.5, PM10) exposure and assisted reproductive technology outcomes in fresh cycles: a systematic review and meta-analysis

Several studies have assessed the relationship between exposure to particulate matter with aerodynamic diameters ≤2.5 μm (PM2.5) and ≤10 μm (PM10) and assisted reproduction technology (ART) success rates, with controversial findings. This review aimed to consolidate the current evidence from fresh ART cycles and explore sources of heterogeneity across studies. The outcomes of interest were biochemical and clinical pregnancy, and live birth. Four exposure timeframes were considered: T0 (within 90 days before starting the stimulation protocol), T1 (from the first day of stimulation protocol to oocyte retrieval), T2 (from oocyte retrieval to embryo transfer), and T3 (from embryo transfer to pregnancy). Database searches were conducted on PubMed/Medline and Embase up to April 2025, using a combination of MeSH/Emtree and generic terms relating to ART patients and air pollution exposure. Fourteen studies, involving 333,438 cycles, were included in the meta-analysis. The studies were conducted between 2010 and 2024 primarily in China (10/14), while 3 were from the USA and one from Korea. We estimated pooled relative risks (RRs) and the corresponding 95% confidence intervals (CIs) for a 10 μg/m3 increase in PM2.5 and PM10 for biochemical pregnancy, clinical pregnancy, and live births, using random-effects meta-analytic models. The pooled RRs for 10 μg/m3 increment in PM2.5 and PM10 at T0 were respectively 0.97 (95%CI: 0.91–1.04) and 0.98 (95%CI: 0.95–1.02) for biochemical pregnancy; for clinical pregnancy they were respectively 0.98 (95%CI: 0.96–1.01) and 0.99 (95%CI: 0.98–1.00). All other findings were close to unity. Substantial heterogeneity was observed across studies for selected outcomes and exposure periods for both pollutants. This systematic review found no significant association between PM2.5 and PM10 exposure and ART outcomes after fresh embryo transfer for any of the four exposure windows.