When it comes to breastfeeding and consuming alcohol, there can be a lot of confusion out there. I thought I would summarise what the effects to the baby there may be, so you can make an informed choice. Many mothers breastfeed for extended periods of time, and often feel like they can’t also let their hair down. But is this really true?

Drinking alcohol while you are pregnant, and drinking alcohol while you are breastfeeding are two totally different things. When you are pregnant, the baby’s blood alcohol level is the SAME as the mother’s. This is because their two circulations are connected by the placenta and alcohol can readily cross over. The foetus’ developing brain is sensitive to the effects of alcohol.

When a breastfeeding mother consumes alcohol, her blood alcohol concentration is the same (or similar) to her breast milk alcohol concentration, as alcohol can easily cross into breast milk. However, when the baby drinks this breast milk, the baby’s liver will then metabolise the alcohol, before producing the baby’s blood alcohol concentration. It is the baby’s blood alcohol concentration that will affect its brain.

To give an example and put this into context: let’s say a mother had drunk enough alcohol to get her blood alcohol concentration to 0.05 (just over the legal limit to drive). This would mean that her breast milk alcohol concentration was about 0.05%. Some fruit juices contain up to 0.01% alcohol; beers are 5% alcohol; and wine is around 13%. Even if the mother had a blood alcohol level of 0.3 (6 times the legal limit to drive), her baby is still only receiving a drink that has 0.3% alcohol. The risk to baby is going to be inadequate parenting, not the alcohol in the milk.

As the mother’s blood alcohol concentration falls, so too does her breast milk alcohol concentration. The alcohol in the breast milk doesn’t stay in there until the breast is emptied; it travels across a concentration gradient. This means there is NO NEED to pump and dump after consuming alcohol. The longer between the last drink and the next breastfeed, the lower the breast milk alcohol concentration.

Alcohol can affect breastfeeding in other ways though. It will often reduce the release of oxytocin. Oxytocin is the hormone that is released with suckling (or thinking about your baby, or when touched etc), and it produces a let-down. Some women may find it harder to get a let-down if they are consuming alcohol. This is one of the reasons why it is advised to limit alcohol consumption in the early days of breastfeeding, while milk supply is getting established. LactMed (an online resourse or app that summarises all the evidence for medication use and breastfeeding) suggests that alcohol decreases milk production after 5 standard drinks, due to this reduced let down.

I think, on the whole, we can be reassured that breastfeeding and alcohol do mix.

by Dr Briony Andrew