Something’s Fishy . . .

Pregnant women want to make sure they are taking every possible prenatal precaution to ensure their children’s healthy development. Although “What to Expect When You’re Expecting” has both helped–and daunted–soon-to-be mothers over the years, doctors still advise them using evidence-based practices derived from rigorous medical testing and a culture of experimentation. The intended result is less adherence to urban legends and more confidence about prenatal health choices.

draftfishoil2Well, sort of. For years, obstetricians told women to take fish oil during their pregnancies. A key ingredient in fish oil is docosahexaenoic acid, or DHA, which is considered integral to cognitive development. The logic was simple: mother takes fish oil, baby receives more DHA, and baby’s IQ rises! The plan sounded remarkably easy, and several observational studies touted its benefits. After all, who wouldn’t want to ensure their child’s acceptance to an elite university just by taking a pill?

In fact, the fish oil “miracle” has left mothers holding little more than snake oil. Despite fish oil’s high DHA quantities, a randomized control trial (“RCT”) using over 500 children with a seven-year follow-up has shown that it produces no difference in cognitive outcomes.  These results no doubt surprised many physicians. Other doctors wisely pointed out critical flaws in the original observational studies. First, their sample sizes were probably too low. Second, those nonrandom samples were most likely subject to pretty important confounding effects. It’s fair to assume that women who took fish oil might already be more health-conscious than those who did not or otherwise differ socioeconomically in ways that would affect their children’s aptitude.

As with many of my previous “spectacular failure” posts, the lesson here is caution when scientific results are the ones we want to believe. Just because they align with our priors should not give them the force of gospel. Nor should we be so skeptical of such findings that we immediately discount them. Rather, we need to push back on preliminary results, making sure they stand up to further, rigorous scrutiny. In the case of fish oil, an RCT helped dispel myth and helped doctors realize that babies pretty much get all the DHA they need. Once they have reached a saturation point, adding more fish oil cannot and does not cause their IQs to reach even greater heights.

But wait . . . there’s more! The RCT suggested that fish oil isn’t completely superfluous. The study also found that mothers taking fish oil might decrease their children’s risk of developing asthma or experiencing premature birth. That said, these outcomes also should undergo need further examination before the OB-GYN community offers its seal of approval.

At the end of the day, fish oil might be more than a placebo; just don’t expect that adding it to your regimen will automatically produce Baby Geniuses.

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