The aim of this study was to evaluate the main sources of and sociodemographic factors associated with second-hand smoke (SHS) exposure, assessed both by questionnaire and by urinary cotinine (UC) levels, in non-smoking pregnant women. We conducted a cross-sectional study in pregnant women from 4 different regions in Spain. A total of 1783 non-smoking pregnant women completed a questionnaire about their previous smoking habit and SHS exposure in their 3rd trimester of pregnancy and provided a urine sample for measuring UC levels. We used logistic regression models to assess the relationship between several sociodemographic variables and some potential sources of SHS exposure. In addition, we analysed the association of several sociodemographic variables and the SHS exposure according to UC levels, using Tobit regression analysis. More than half of women (55.5%) were exposed to SHS in their 3rd trimester of pregnancy. The following variables were associated with SHS exposure: having smoked previously, low educational level, and being primiparous. Data collection after the first law banning smoking in public places was associated with lower risk of SHS exposure in restaurants and at work. UC levels were higher among women exposed to more than one source. Having a partner who smoked at home was the source of SHS with the greatest impact on UC levels, followed by having a partner who smoked but not at home, other people smoking in the household, being exposed during leisure time, at work and at restaurants. The most important source of SHS exposure was exposure at home. Prevention of SHS exposure should be addressed not only with pregnant women but also with their families.
Keywords: Biological monitoring; Cotinine; Passive smoking; Pregnant women; SHS.
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