Prenatal fish oil supplementation associated with lower risk of asthma in children: The COPSAC trial

1. Third trimester supplementation with long-chain polyunsaturated fatty acids (LCPUFA) reduces offspring risk of asthma or persistent wheeze and risk of lower respiratory tract infections (LRTI).

Evidence Rating Level: 1 (excellent)  

Study Rundown: Asthma is a chronic disease that affects approximately 20% of young children, with the cost of care for these patients between 2005 and 2009 estimated as a little over $10 billion. The association between poor prenatal intake of n-3 LCPUFAs and increased risk of asthma in offspring has been suggested by observational studies, but randomized controlled trials have offered mixed results. In the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC), researchers aimed to determine if supplementation of n-3 LCPUFAs in pregnant women during their trimester would reduce the risk of asthma in their offspring up to 5 years of age. The results demonstrated that third trimester n-3 LCPUFA supplementation reduced the absolute risk of asthma and LRTI (i.e. bronchitis, pneumonia) in offspring. Specifically, the risk of asthma in offspring was reduced by 6%, and this effect was most pronounced in women with low pre-study levels of omega-3 fatty acids. The number needed to treat to prevent one case of asthma was 14.6 in the total cohort. Overall, the trial is well-powered with good longitudinal follow-up but with some recruitment bias (participants vs. nonparticipants differed in employment and income level). The clinical implications of this study suggests that prenatal supplementation with n-3 LCPUFAs may contribute to the prevention of asthma and respiratory infections in young children.

Click to read the study, published today in NEJM

Relevant Reading: The global burden of asthma: executive summary of the GINA Dissemination Committee Report

In-Depth [randomized controlled trial]: In this single-center, double-blind placebo-controlled trial, 736 women between 22-26 weeks of gestation were randomly assigned to receive either n-3 LCPUFA (fish oil) or placebo (olive oil) daily up until 1 week after delivery. The final study included 695 children and pediatricians collected clinical data for visits at 1 week after birth, then at 1, 3, 6 months and every 6 months until 36 months and then yearly after until 5 years. A total of 95.5% of children completed the 3-year double-blind follow-up. The primary endpoint was risk of asthma, which was 16.9% vs. 23.7% in the n-3 LCPUFA and placebo groups, respectively (HR 0.69; 95%CI 0.49-0.97; p = 0.035). In a subgroup analysis that stratified women by pre-intervention levels of omega-3 fatty acids, the study showed that this protective effect against asthma was strongest in women with the lowest pre-intervention levels of omega-3 fatty acids. Secondary endpoints included risk of LRTI, asthma exacerbations, eczema or allergic sensitization. Supplementation reduced risk of LRTIs in the treatment compared to the control group (31.7% vs 39.1%; HR 0.75; 95%CI 0.58-0.98; p = 0.033), however, there was no significant association between groups for asthma exacerbations, eczema or allergic sensitization.

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