A large, double blind study out of Denmark suggests that fish oil during pregnancy may help lower a child's risk of asthma, reports the New York Times, reducing rates from 24% in women given placebos to 17% in those given fish oil in the final trimester, amounting to a 31% reduction in risk. And while they're not ready to recommend that pregnant women take fish oil, the lead researcher tells NPR his team was surprised by the "magnitude" of the reduction. The difference was more pronounced among children of mothers who had low levels of fatty acids called EPA and DHA in their blood: By age 3, 17.5% of children whose mothers took fish oil had developed asthma, while that number was 34.1% among those of mothers who took the placebo. That's a reduced risk of 51%. An NIH expert writes in an accompanying editorial that factors such as these may allow development of "precision medicine" aimed at women most likely to benefit.
Reporting in the New England Journal of Medicine, the researchers suggest that in spite of the conflicting conclusions in previous studies, fish oil's effect on inflammatory diseases is becoming more clear. Because small airways in the lungs further restrict when they are inflamed, and lab studies have found that lipids in fish oil could help infant airways counteract inflammation, fish oil may, at the right dose and in the right population of pregnant women, have a positive effect on developing fetuses. But until more large studies are done replicating these findings and determining when and how much which pregnant women should take fish oil to reduce their offspring's risk of asthma, doctors aren't likely to start recommending it. (Is fish oil more like snake oil?)