STUDY QUESTION: Does dietary n-3 long chain polyunsaturated fatty acid (LCPUFA) supplementation of pregnant women with a fetus at high risk of allergic disease reduce immunoglobulin E associated eczema or food allergy at 1 year of age? SUMMARY ANSWER: n-3 LCPUFA supplementation in pregnancy did not reduce the overall incidence of immunoglobulin E associated allergies in the first year of life, although immunoglobulin E associated eczema was lower. WHAT IS KNOWN AND WHAT THIS PAPER ADDS: Several mechanistic studies have suggested that higher intakes of n-3 LCPUFA during pregnancy modulate the neonatal immune response towards a less allergenic phenotype. n-3 LCPUFA supplementation in pregnancy did not reduce the incidence of immunoglobulin E associated food allergies in the first year of life, but the incidence of atopic eczema was lower. [ABSTRACT FROM AUTHOR]