Drinking alcohol while breastfeeding: Will it harm your baby?

Dr. Koren is the founder and director of the Motherisk Program and professor of Paediatrics, Pharmacology, Pharmacy, and Medical Genetics at the University of Toronto. He is also the Richard and Jean Ivey Chair in Molecular Toxicology in the Schulich School of Medicine, at The University of Western Ontario, where he holds the rank of professor in Medicine and Paediatrics.


If you have recently delivered a healthy, full-term baby and are now breastfeeding exclusively, you may be wondering if drinking alcohol could harm your nursing baby.

Ample evidence indicates that drinking alcohol during pregnancy poses a severe and avoidable risk to unborn babies. However, some mothers are still advised by physicians, nurses, lactation consultants, family members and friends, that it is all right to drink, even though an acceptable level of alcohol in breast milk has never been established.

Alcohol consumed by a mother passes easily into her breast milk at concentrations similar to those found in her bloodstream. Although a nursing infant is actually exposed to only a fraction of the alcohol the mother ingests, infants get rid of alcohol very slowly in their first weeks of life. There are studies that show impaired motor development, changes in sleep patterns, decrease in milk intake and risk of hypoglycemia (low blood sugar) when the baby suckles the mother’s alcohol.

At this time, the possibility of adverse effects has not been ruled out. However, occasional drinking does not warrant discontinuing breastfeeding, as the benefits of breastfeeding are extensive and well recognized. But, until a safe level of alcohol in breast milk is established, no alcohol in breast milk is safest for nursing babies. Therefore, it is wise for mothers to delay breastfeeding their babies until alcohol is completely cleared from their breast milk.

Previous guidelines for determining the time needed to eliminate alcohol from breast milk were rough estimates based on the number of drinks consumed. By also taking into account the mother's weight, which affects milk-alcohol concentration, a more accurate estimate of how long a nursing mother should delay breastfeeding can be determined.

To help you, the Motherisk team produced a table to show breastfeeding mothers how long it takes to eliminate alcohol completely from breast milk. This depends on your body weight and on how many drinks you have had.

Carefully planning a breastfeeding schedule and waiting for alcohol to completely clear from your breast milk can ensure that your baby is not exposed to any alcohol.


This research was supported by the Brewers Association of Canada and the Research Leadership for Better Pharmacotherapy during Pregnancy and Lactation.

Copyright © 2011 The Hospital for Sick Children, Toronto, Ontario, Canada. All rights reserved.

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