Assessment of prenatal SHS exposure
SHS exposure after birth was assessed using self-reported
questionnaires. Mothers were asked to complete the questionnaire at week
36 of pregnancy. They were considered to have been exposed to SHS if
they answered “Yes” to the question: “Were you exposed to secondhand
smoke during the period of this pregnancy?”. For quantitative
assessment, urine cotinine levels of the pregnant mothers were measured
at gestational week 36.