Wang X, et al. - Researchers investigated how outdoor air pollution affects the outcomes of frozen–thawed embryo transfer (FET) and fresh transfer in IVF treatment via retrospectively studying a cohort of 11,148 patients who contributed to 16,290 transfer cycles between January 2013 and December 2016. Using inverse distance weighting interpolation, researchers determined the daily ambient exposures to six pollutants (PM_2.5, PM₁₀, SO₂, NO₂, CO, O₃) at an IVF clinical site, according to the data from fixed air quality monitoring stations in the city. Outcomes revealed lower live birth rates following FET in significant correlation with increased SO₂ and O₃ levels at the site of IVF unit. However, these were not identified affecting the contemporary fresh transfer outcomes.