If you ingest caffeine when you’re breastfeeding it can pass into your milk, and may therefore be consumed by your baby1. From a health perspective, this is not a cause for great concern. Low doses of caffeine are not regarded as harmful, and indeed caffeine is sometimes administered to preterm babies to help reduce apnea (pauses in breathing of more than 20 seconds)2. The stimulant properties of caffeine that make it suitable for therapeutic use, however, could potentially affect babies in a less desirable way — in particular, by making them wakeful and irritable.
So, how likely is it that drinking too much coffee will cause your baby to lose sleep? Research investigating this issue shows that moderate levels of consumption aren’t likely to cause any problems. A study examining the levels of caffeine over a 12 hour period in the milk of women drinking their usual caffeinated beverages found that consumption of less than 100mg (roughly the amount in a single espresso) did not pass into milk at a detectable level3. It also found (as did an earlier study1) that the amount of caffeine that makes it into milk is greatly reduced — between 0.06% and 1.5% of the maternal dose — and that the level peaks an hour after consumption, and then declines, disappearing completely after 12 hours.
Could this small amount of caffeine cause sleeplessness? The available evidence indicates this is unlikely. In a study examining this issue, 11 breastfeeding mothers drank 5 cups of decaffeinated coffee a day over a 5 day period, and 5 cups a day of decaffeinated coffee with 100mg caffeine added over another 5 days4. The results showed that the babies’ average heart rates and the amount of sleep they got over a 24 hour period remained the same, regardless of whether their mothers had consumed caffeine.
According to the American Academy of Pediatrics, ‘moderate consumption of tea, coffee and caffeinated sodas is fine when you’re breastfeeding’. Although babies can ingest caffeine through breast milk, if their mothers are drinking around 5 cups of coffee a day it is unlikely to impact on sleep levels. People metabolize caffeine at different rates, of course, and young babies do it much more slowly than adults5, so it’s not impossible that drinking coffee will affect your baby, particularly if you consume it in large amounts. At low levels of consumption the chances of this being a problem are small, however, so most breastfeeding mothers can enjoy a coffee, tea or cola safe in the knowledge that is keeping them, but not their baby, awake.