Effects of exposure to high levels of particulate air pollution during the follicular phase of the conception cycle on pregnancy outcome in couples undergoing in vitro fertilization and embryo transfer.

The objective of this retrospective cohort study was to assess the potential effects of preconceptional short-term exposure to particulate air pollution in a real-world situation on pregnancy outcome in infertile women evaluating the possible role of IVF/embryo transfer treatment on this outcome using women who had conceived naturally for the first time during the same time frame as a matched control group. The study provides evidence for an association between brief exposure to high levels of ambient particulate matter (aerodynamic diameter <or=10 microm) during the preconceptional period and early pregnancy loss, regardless of the method of conception, and showed a 2.6-fold increase in risk of miscarriage, suggesting a threshold instead of a monotonic effect of this exposure on reproductive outcome.