Will Alcohol During Pregnancy Alter My Baby’s Brain?

A new study was released that says even small amounts of drinking during pregnancy alter a baby’s brain structure. Given that a lot of your writing has stated that drinking during pregnancy is okay, what do you think?
—Concerned Mom

Studies such as these come out often and were a part of the inspiration behind my writing Expecting Better. The particular study you reference is here. It is, at this point, an unpublished abstract. What the authors do is study fetal MRI scans for 20 babies whose mothers have some degree of prenatal alcohol exposure and compare them with age-matched controls without exposure. They report two differences — in two brain measures — across groups.

When reading about data like this, it’s first important to put it in the context of the vast existing literature on these relationships. I talked about this in Expecting Better, I’ve written about it in follow-ups (like here), and I’ve written about new research in this newsletter (i.e. here). It’s the one section of Expecting Better that I’ve carefully revisited every time I revise the book. This is a hard question to answer because of many underlying differences between women who drink in pregnancy and those who do not, but when we isolate papers that do a better job for controlling for these differences, we do not see evidence of negative impacts of occasional alcohol consumption.

The release of new studies, especially those with seemingly fancy outcome measures, is always notable. But all studies should be evaluated in the context of existing work.

In the particular case of this study, the unfortunate truth is that right now there is absolutely no way to evaluate what it means. The abstract contains no information about the amount of drinking in the drinking group. The authors reported more information about this in the press release but did not provide many details. There is no other information about the treatment versus control group, making it hard to evaluate whether there were other important differences (as there often are). We do not have a full sense of the outcomes they considered or the statistical methods used. The outcomes they cite are not well-understood — fetal brain science being in its infancy — so it’s hard to know if they have any clinical significance at all.

Bottom line: There isn’t enough information here to really comment in detail. But the existing work is voluminous.