Can fish oil supplements taken during pregnancy prevent asthma in children? According to a randomized trial in the New England Journal of Medicine, yes. Children of 736 pregnant women who took supplements containing given n-3 long-chain polyunsaturated fatty acid during their third trimester had a 31% relative reduction in risk of developing asthma or persistent wheezing as young children, as compared with kids whose mothers took olive oil (17% versus 24%, HR 0.69, 95% CI 0.49-0.97, P=0.035), according to Hans Bisgaard, MD, head of the Pediatric Asthma Center of the University of Copenhagen in Denmark, and colleagues.