Infertility, Pregnancy Loss and Adverse Birth Outcomes in Relation to Maternal Secondhand Tobacco Smoke Exposure.

A substantial proportion of the etiology involved in female infertility and adverse pregnancy outcomes remains idiopathic. Recent scientific research has suggested a role for environmental factors in these conditions. Secondhand tobacco smoke (STS) contains a number of known or suspected reproductive toxins, and human exposure to STS is prevalent worldwide. Robust evidence exists for the toxic effects of active smoking on fertility and pregnancy, but studies of passive exposure are much more limited in number. While the association between maternal STS exposure and declined birth weight has been fairly well-documented, only recently have epidemiologic studies begun to provide suggestive evidence for delayed conception, altered menstrual cycling, early pregnancy loss (e.g. spontaneous abortion), preterm delivery, and congenital malformations in relation to STS exposure. There is also new evidence that developmental exposures to tobacco smoke may be associated with reproductive effects in adulthood. To date, most studies have estimated maternal STS exposure through self-report even though exposure biomarkers are less prone to error and recall bias. In addition to utilizing biomarkers of STS exposure, future studies should aim to identify vital windows of STS exposure, important environmental co-exposures, individual susceptibility factors, and specific STS constituents associated with female infertility and adverse pregnancy outcomes. The role of paternal exposures/factors should also be investigated.