Newborn infant urinary cotinine and birth outcomes in the Jerusalem Environment Mother and Child Cohort Study

Background: Environmental tobacco smoke (ETS) exposure during pregnancy can cause preterm delivery and childhood cancer. The aim of this study was to measure ETS exposure in pregnant women and in newborn infants in Israel using urinary cotinine measurements, to assess predictors of ETS exposure in these vulnerable groups, and to assess associations with birth effects (birth weight, birth length, head circumference) in newborn infants. Methods: We analyzed urinary cotinine and creatinine in 265 non-smoking pregnant women and 97 newborns, and analyzed associations with self-reported exposure to ETS, paternal smoking, sociodemographic variables and with birth outcomes (birth weight, birth length, head circumference). Results: 37.7% of pregnant women and 29.0% of infants had urinary cotinine concentrations above the level of quantification (LOQ) of 1 μg/L, whereas 63.8% and 50.5%, respectively, had urinary cotinine concentrations above the level of detection (LOD) of 0.5 μg/L. Median unadjusted and creatinine adjusted urinary concentrations of cotinine in pregnant women were 0.7 μg/L, and 0.9 μg/g creatinine, respectively, and in newborn infants were 0.5 μg/L, and 1.3 μg/g creatinine, respectively. We did not find an association between maternal and infant urinary cotinine level. Maternal (but not infant) urinary cotinine was significantly associated with paternal smoking (p < 0.05). Infant (but not maternal) cotinine above the LOQ was negatively associated with birth weight (p < 0.05). Conclusions: In this high socioeconomic cohort, almost a third of newborn infants born to non-smoking mothers had quantifiable levels of urinary cotinine. This is the first study showing that newborns with quantifiable urinary cotinine levels have lower birth weight.