Sources and frequency of secondhand smoke exposure during pregnancy.

introductionThis study examined sources of exposure to secondhand smoke (SHS) during pregnancy and misclassification of women as having no SHS exposure if partner smoking was used as the only measure of SHS exposure. We also examined changes in SHS exposure across the three trimesters of pregnancy.

methodsThe sample consisted of 245 pregnant women who were in a serious relationship with a partner and 106 for examination of change over time. Women's smoking status was determined by a combination of self-reports and oral fluid assays. Women's reports of partner smoking, smoking by other social network members, and frequency of exposure to SHS were obtained.

resultsThe most common source of SHS exposure during pregnancy was the partner (n = 245). However, reliance on the partner smoking measure alone would have misclassified a substantial number of women as having no SHS exposure during pregnancy. The importance of exposure from the general social network was also evident in the finding that among nonsmoking women with nonsmoking partners, 50% reported some level of SHS exposure in the preceding week. Contrary to expectations, there were no changes in SHS exposure across the three trimesters of pregnancy (n = 106).

conclusionsResults highlight the need for treatment plans to target sources of exposure from other members of women's social networks in addition to partners. It may be unrealistic to expect women's cessation efforts to be successful in the face of consistent and continued SHS exposure through pregnancy.