Choe SA, et al. - Researchers investigated if the concentrations of five criteria air pollutants are associated with probabilities of biochemical pregnancy loss and intrauterine pregnancy in women. They noted an association of increased concentrations of ambient particulate matter (PM₁₀), nitrogen dioxide (NO₂), carbon monoxide (CO) during controlled ovarian stimulation (COS) and after embryo transfer with a decreased probability of intrauterine pregnancy. Observations thereby indicated that lower intrauterine pregnancy rates in IVF cycles could be associated with ambient air pollution during COS and the post-transfer period.