(HealthDay)—For women in the third trimester of pregnancy, supplementation with n-3 long-chain polyunsaturated fatty acids (LCPUFAs) is associated with a reduction in the risk of persistent wheeze and asthma in offspring, according to a study published in the Dec. 29 issue of the New England Journal of Medicine.

Hans Bisgaard, M.D., from Herlev and Gentofte Hospital in Hellerup, Denmark, and colleagues randomized 736 at 24 weeks of gestation to 2.4 g n-3 LCPUFAs or placebo. Their children formed the Copenhagen Prospective Studies on Asthma in Childhood2010 cohort and were followed prospectively. For the first three years of the children's lives, neither the investigators nor the participants were aware of the group assignments.

Six hundred ninety-five children were included in the trial and 95.5 percent completed the three-year follow-up period. The researchers found that the risk of persistent wheeze or was 16.9 and 23.7 percent in the treatment and control groups, respectively (hazard ratio, 0.69), corresponding to a relative reduction of 30.7 percent. Children of women whose blood levels of eicosapentaenoic acid and docosahexaenoic acid were in the lowest third of the trial population at randomization had the strongest effect (17.5 versus 34.1 percent; hazard ratio, 0.46).

"Supplementation with n-3 LCPUFA in the third trimester of pregnancy reduced the absolute risk of persistent wheeze or asthma and infections of the in offspring by approximately 7 percentage points, or one-third," the authors write.

One author disclosed financial ties to the pharmaceutical industry; two authors reported being named on a pending patent relating to the prevention of through FADS genotyping.