A study appearing in the journal Pediatrics suggests that drinking while breastfeeding may affect cognitive outcomes in children.

Imagine you’re a breastfeeding mother. You’re up all hours of the night, you’re trying to manage your entire life plus a completely helpless newborn, and tonight, at last, you secured a trustworthy babysitter so you can have a dinner out with other adults. Should you have that glass of wine?

This study, appearing in the Journal Pediatrics suggests that, no, drinking alcohol while breastfeeding can affect the cognitive development of your child.

This is an easy study to hype – the news segments write themselves: “Is your baby being harmed by your breastmilk? Tune in at 11”. But, digging into this study a bit, I’m not particularly worried.

Researchers used the “Growing up in Australia” database, a longitudinal study of over 5000 Australian children to ask whether drinking alcohol while breastfeeding was associated with poorer performance in three cognitive domains: vocabulary, non-verbal reasoning, and early literacy.

The big conclusion you’ll hear is that moms who drank while breastfeeding had kids who did worse on non-verbal reasoning tasks at age 6-7. The analysis was done well and adjusted for a lot of other things like drinking during pregnancy, smoking, income, etc.

But before we add yet another thing for new moms to feel guilty about, let’s look at the data a little more deeply.

First, the observed relationship was only seen among moms who HAD breastfed but WEREN’T breastfeeding when the baby was enrolled in the study at around 6-18 months of age. That’s odd, right? I mean, if drinking while breastfeeding is bad, wouldn’t the kids who were breastfed more do worse? Is the implication that, once you start drinking while breastfeeding, you better keep it up?

OK, maybe the alcohol in breast milk is only bad early on in life.  Maybe, but surely in utero alcohol would have a worse effect. But in this study, drinking during pregnancy was NOT associated with any of the developmental outcomes. That’s a really odd finding, and in contrast to multiple prior studies which suggest that drinking during pregnancy can be harmful.

I asked lead author Louisa Gibson about this finding. She suggested that perhaps there was some social desirability bias here – moms didn’t want to admit to drinking while pregnant, so the exposure was muddled.

By the way, smoking during breastfeeding wasn’t associated with any differences in cognitive function either.

So, in case you’re keeping score, I made a little chart of the positive associations in this study:

I don’t have a great way to make sense of this. It feels like there are some positive controls in this study that didn’t come out positive, which should probably call the primary results into question.

Should women drink while breastfeeding? According to the American Academy of Pediatrics, moderation is advised.

But in all these studies about young children, the mothers often take a back seat. By focusing so exclusively on the children’s outcomes, we end up imposing restrictions on mothers that make them feel like they are completely subservient to the needs of their children. This is not a good thing for moms or their kids frankly. A happy mom is a good mom.

So breastfeeding moms, I wouldn’t let this particular study scare you off from that glass of wine tonight. You’ve got enough to worry about.

Update (8/1/2018): Dr. Gibson points out that the group in whom the association was seen was those who had been breastfeeding AND were currently breast feeding. The association was not seen in those who were currently breastfeeding exclusive of those who had been breastfeeding.