Is it safe to drink alcohol while breastfeeding?
Dr. Stephanie Liu with her first child. Credit: Stephanie Liu

Is it safe to drink alcohol and breastfeed? As physicians, we have always cautioned patients not to. As mothers, we look forward to the occasional glass of wine.

We also know that drinking while breastfeeding remains a controversial and very , one for which many mothers find themselves judged by friends and family.

Does beer increase milk supply?

Historically, beer was made very differently than it is today. Beer companies marketed low-alcohol beers to women to stimulate appetite, increase their strength and enhance milk production. Barley used in beer production contains a polysaccharide that can enhance breast milk production by increasing prolactin secretion in nursing mothers.

On the other hand,  may also inhibit breast milk letdownand slow the flow of  to the baby due to a blunted prolactin response required for breast milk production. An older study published in Developmental Psychobiology also found that infants consumed less milk during the four-hour testing sessions in which nursing mothers drank alcoholic beer compared to mothers who drank nonalcoholic beer.

Alcohol consumption may cause a woman’s breasts to feel fuller, giving the illusion of enhanced milk production when in fact there is less milk transferring to the baby.

How much alcohol will reach your baby?

The amount of alcohol present in your breast milk is closely related to the amount of alcohol present in your bloodstream. The highest amount of alcohol level in your breast milk occurs 30 to 60 minutes after an alcoholic drink.

Many studies have been performed that measure the amount of alcohol that gets into breast milk and thus into baby. One study found that consuming 250 ml of wine had a very small impact on the baby’s blood alcohol level.

The legal driving limit for blood alcohol concentration in many cities is 0.05 percent. This correlates to 50 mg of alcohol in 100 ml of blood. Because the amount of alcohol present in your breast milk is closely related to the amount of alcohol in your bloodstream, the amount transferred to your baby depends upon your blood alcohol level at the time of nursing.

For example: If your baby drinks 100 ml of breast milk while you have a blood alcohol level of 0.05 percent, your baby will consume 50 mg of alcohol. For a 5 kg baby, this is 0.001 percent of their body weight in alcohol.

Put another way: a standard drink (defined as one 355 ml can of beer, one 150 ml glass of wine or 45 ml of hard liquor) contains approximately 14,000 mg of alcohol. If your baby drinks 100 ml of breast milk while you have a blood alcohol concentration of 0.05 percent, this is nearly equivalent to your baby drinking 1.5 ml of beer, or 0.5 ml of wine or 0.2 ml of hard liquor.

Wait at least two hours before nursing

Ultimately, just as in pregnancy, there is no known safe level of alcohol consumption while breastfeeding. We cannot know for certain the safety of even small amounts of alcohol for young .

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