Approximately 25% of American women of reproductive age smoke tobacco, and many continue to smoke during and after pregnancy despite the known potential harm to their own health and to their child’s health. These health threats remain after the child’s birth as the baby is exposed to nicotine and other toxins in both ambient air and breast milk.

Despite the fact that the amount of nicotine transferred into breast milk is more than double the quantity transferred through the placenta during pregnancy, there is strong evidence that breast milk itself provides protection: the incidence of respiratory illness among infants who were breastfed by mothers who smoked was lower when compared with babies who were formula fed. As it appears that the benefits of breastfeeding outweigh the risks of nicotine exposure, nicotine is no longer listed as a drug that is contraindicated during breastfeeding.

Women are strongly encouraged to breastfeed but the ones who smoke are more likely to have a lower milk supply, and those who do breastfeed tend to wean their babies earlier than women who don’t smoke. Studies indicate that smoking more than 10 cigarettes per day decreases milk production and alters milk composition. Furthermore, mothers who smoke are more likely to think that their milk supply is inadequate and are less motivated to breastfeed. Finally, breastfed babies whose mothers smoke more than 5 cigarettes daily exhibit behaviors (e.g. colic and crying) that may promote early weaning.

In addition, because smoking is associated with sleep disturbances in adolescents and adults, researchers have begun to look at the sleeping patterns of babies breastfed by mothers who smoke. They found that the infants of mothers who smoke just before nursing have shorter sleep times and altered sleep architecture.

While there is still little evidence to suggest that smoking mothers has significant adverse effects on their infants, the lack of evidence may be due to the insufficiency of investigation. More research needs to done to address the effects of smoking and breastfeeding not only in the acute phase but also in the long-term, analyzing the possible developmental and behavioral impairments associated with nicotine exposure. Furthermore, there is a clear need for effective smoking cessation treatments for breastfeeding women and also awareness about the consequences of smoking.

M. Pia Rogines Velo Sardi, MD PhD

Mennella JA, Yourshaw LM, Morgan LK. Breastfeeding and smoking: short-term effects on infant feeding and sleep. Pediatrics. 2007 Sep;120(3):497-502.