Impact of air pollution on fertility: a systematic review.

Air pollution has gained considerable interest because of the multiple adverse effects reported on human health, although its impact on fertility remains unclear. A systematic search was performed to evaluate the impact of air pollutants on fertility. Controlled trials and observational studies assessing animal model and epidemiological model were included. Occupational exposure and semen quality studies were not considered. Outcomes of interest included live birth, miscarriage, clinical pregnancy, implantation, and embryo quality. Ten studies were included and divided into two groups: animal studies and human epidemiological studies including the general population as well as women undergoing in vitro fertilization and embryo transfer (IVF/ET). Results from this systematic review suggest a significant impact of air pollution on miscarriage and clinical pregnancy rates in the general population, whereas among subfertile patients certain air pollutants seem to exert a greater impact on fertility outcomes, including miscarriage and live birth rates. Besides, studies in mammals observed a clear detrimental effect on fertility outcomes associated to air pollutants at high concentration. The lack of prospective studies evaluating the effect of air pollution exposure in terms of live birth constitutes an important limitation in this review. Thus, further studies are needed to confirm these findings.