Maternal exposure to second-hand tobacco smoke and pregnancy outcome among couples undergoing assisted reproduction.

BACKGROUND: Exposure to second-hand tobacco smoke is preventable, yet common. This study assessed relationships between maternal exposure to second-hand tobacco smoke and adverse pregnancy outcomes.
METHODS: We measured cotinine (a biomarker of tobacco smoke) in urine from 921 women undergoing assisted reproductive technologies (ARTs) between 1994 and 1998. We also collected information on self-reported exposure to second-hand smoke at home or at work, in addition to parental smoking during the women's childhood.
RESULTS: In crude analysis, creatinine-adjusted cotinine levels were associated with a slight decrease in implantation rate among non-smoking women (11.1% in the lowest cotinine quintile versus 8.2% in the highest cotinine quintile; P=0.13). However, in multivariate logistic regression, cotinine levels above the median were not associated with failed fertilization, failed implantation or spontaneous abortion, nor was there evidence of a dose-response relationship among cotinine quintiles. After excluding women in couples diagnosed with male factor infertility, there were increased odds of having a spontaneous abortion among non-smoking women who reported that both parents smoked while they were children growing up compared with women reporting that neither parent smoked [adjusted odds ratio (OR) = 4.35; 95% confidence interval (CI) = 1.04-18.1].
CONCLUSIONS: Female exposure to second-hand smoke as a child or in utero may be associated with an increased risk of spontaneous abortion in adulthood. However, this may be a chance finding due to multiple comparisons. Similar associations should be explored in additional studies with more refined estimates of childhood and in utero exposure to tobacco smoke.