Nicotine is a toxic chemical naturally found in tobacco plants and released during smoking. It is very addictive and stimulates the nervous system, increases the heart rate and blood pressure (and causes other harmful effects (drugabuse.com, 2012). For a review of how smoking affects your baby see Smoking While Breastfeeding. This article looks in more detail at how nicotine in breast milk might affect the breastfed baby.
Does nicotine get into breast milk?
Yes, nicotine is readily absorbed into breast milk from the mother’s blood whenever she smokes or uses nicotine replacement therapy 1 and her baby will also breathe in nicotine directly if exposed to side smoke.
Passive smoking vs nicotine in breast milk
Bajanowski et al found nicotine levels in a baby’s blood were much greater from passive smoking than from ingesting nicotine in breast milk 2. However another study found ten times as much cotinine (a metabolite of nicotine with a much longer half life that can be measured in blood, urine, saliva, hair and nails) in breastfed babies of smoking mothers compared with bottle fed babies of smoking mothers 3 suggesting more nicotine came via the milk.
Benefits of breastfeeding
Although nicotine moves readily into breast milk, breastfeeding is thought to outweigh the risks of nicotine exposure compared with formula feeding because breastfeeding protects against respiratory infections and has many other benefits 4. However, Mennella et al suggest more research is still needed:
The removal of nicotine from the list of drugs contra-indicated during lactation does not diminish the need for more research on the effects of smoking during lactation.
cigarette smoke is a complex mixture of chemicals with ~4000 compounds, including >60 carcinogens. Whether compounds other than nicotine and cotonine [a metabolite of nicotine] are transferred to human milk with similar time courses and, if so, what levels are transmitted remain unknown.
Nicotine in breast milk
Nicotine in breast milk can:
- Flavour milk and is a known appetite suppressant 5.
- Cause fussy behaviour, breast refusal, excessive crying, and increased colic in mothers who smoke more than five cigarettes per day 6.
- Lead to vomiting and nausea if a mother is smoking 20 cigarettes or more daily 7.
- Cause diarrhoea (Fisher, 2006)
- Increase baby’s heart rate (Fisher, 2006)
- Cause disturbed sleep with more nicotine exposure because nicotine is a stimulant (Menella et al, 2007)
- Increase the risk of SIDS by affecting the way a baby can resuscitate during hypoxic episodes (when the body doesn’t have enough oxygen) 8.
- Interfere with normal infant lung development (Lactmed).
- Reduce prolactin levels (a hormone needed for making breast milk) and so affect milk supply although not all studies agree 9.
- Be a risk factor for childhood obesity and thyroid dysfunction 10 11.
It is not clear whether there comes a time when a certain number of cigarettes smoked and hence the amount of nicotine and other substances crossing into milk could outweigh the benefits of breast milk. Certainly it would be better for your baby not to add nicotine to your breast milk. However, until research provides an answer, a smoker’s breast milk has many health advantages for your baby just as all breast milk does. It contains living cells and unique nutrients that both grow your baby’s brain and body normally and protect it from infections. Formula has none of these protective substances and has its own risks 12.
How long does nicotine stay in breast milk?
Nicotine readily moves into breast milk during smoking. The amount of nicotine in breast milk is highest by the time you finish your cigarette. Over the next two hours the concentration of nicotine halves 13. It would take about ten hours for nicotine to completely leave the blood or breast milk without a trace—based on the general guide that it takes five half lives to completely clear a substance from the body. In practice although nicotine isn’t stored in breast milk, the levels of nicotine in a mother who smokes regularly throughout the day will accumulate over 24 hours with each cigarette she smokes 14 and breakdown products of nicotine e.g. cotonine remain for much longer.
smoking represents a multiple dosing situation with considerable accumulation while smoking and persistent levels for 24 h of each day.
When is the best time to smoke if I am breastfeeding?
Waiting as long as possible after smoking gives time for the nicotine levels to drop. Nicotine levels in breast milk fall by half after about two hours. As breastfed babies generally want to feed at least every two hours, general advice is that smoking straight after breastfeeding will give time for nicotine levels time to come down before the next breastfeed.
What about other chemicals in breast milk and cigarette smoke?
Tobacco contains much more than just nicotine. Lung.org15 credits 600 different ingredients to cigarettes from nicotine, tar, and arsenic to carbon monoxide, lead and many more. When smoked, these 600 chemicals become thousands of harmful pollutants that both you and your baby can breathe in. Passive smoking puts your baby at a much higher risk of sudden infant death syndrome 16. And not only nicotine will cross into breast milk—so will other chemicals.
mothers unable to stop smoking should be informed of the possibility that harmful chemicals derived from tobacco smoke may be transmitted to their infants via breast milk.
See Smoking While Breastfeeding for more about the effects of cigarette smoking during breastfeeding.
What about nicotine replacement therapy?
For more information about nicotine replacement therapy including patches, gum, and sprays, and for guidance on e-cigarettes, vaping and breastfeeding, see Nicotine Therapy, Vaping and Breastfeeding.
Nicotine has several side effects for your baby when breathed in via cigarette smoke or swallowed via breast milk. Current health guidelines 17 18 19 advise mothers to protect their babies from smoke inhalation and to reduce nicotine exposure via breast milk by smoking straight after a breastfeed and smoking as little as possible.