Exposure to environmental tobacco smoke is associated with adverse effects in infants and children.
To explore whether an increase in urinary cotinine fumarate level is caused by ingested nicotine and cotinine in breast-feeding infants.
We studied newborns at risk for developing asthma and allergies based on a strong family history. We measured urinary cotinine levels in the infants as a measure of environmental tobacco smoke exposure and cotinine levels in the breast milk of breast-feeding mothers.
Of 507 infants, urinary cotinine levels during the first 2 weeks of life were significantly increased in infants whose mothers smoked. Breast-fed infants had higher cotinine levels than non–breast-fed infants, but this was statistically significant (P<.05) only if mothers smoked. Urinary cotinine levels were 5 times higher in breast-fed infants whose mothers smoked than in those whose mothers smoked but did not breast-feed.
Mothers should be encouraged to not smoke, and parents must be advised of the potential respiratory and systemic risks of environmental tobacco smoke exposure to their child, including the potential for future addiction to smoking.