Nicotine exposure in breastfed infants

To study exposure to nicotine in breastfed infants in relation to parental smoking habits.

Forty mother-infant pairs were studied. Twenty non-smoking mothers, 18 smoking (2-20 cigarettes per day) and two snuff-taking mothers were included. All infants were healthy, exclusively breastfed and their postnatal age was 6 wk. During a home visit, parental smoking habits were recorded, and the time of mothers' last smoke or taking of snuff and breastfeeding were recorded. Breast milk and infant urine samples were collected. Concentrations of nicotine and cotinine were analysed with gas chromatography. The amount of milk ingested during the home visit was calculated by weighing the infants.

Two non-smoking and non-snuff-taking women had milk containing nicotine (28 and 13 microg/l, respectively). Both had smoking spouses. In the smoking and snuff-taking group, the mean (SD) milk nicotine concentration was 44 (38) microg/l (n = 36). When milk samples taken 7 h and 0.6 h after smoking were compared, the concentration of milk nicotine increased from 21 to 51 microg/l (p < 0.01). The two snuff-taking mothers exposed their children to higher milk nicotine concentrations than all but two of the smokers. The concentrations of the metabolite cotinine in infant urine correlated with the dose of nicotine ingested during the home visit (r = 0.84, p < 0.01).

Breastfed infants with a smoking or snuff-taking mother are exposed to nicotine in breast milk. The mean intake of nicotine via milk is 7 microg/kg/d. With a shorter time between the mothers' smoking and breastfeeding, the milk nicotine concentration will increase. Both passive smoking at home and snuff-taking were associated with measurable nicotine levels in milk. Healthcare personnel promoting breastfeeding should be aware of these factors influencing exposure to nicotine in the breastfed infant.