New research shows that pregnant women who take fish oil supplements during their pregnancy, as well as during their child’s infancy and nursing, have children with far fewer allergy problems:

In a recent study, 145 pregnant mothers from families with high risk of allergy and asthma were either given a fish oil supplement or a placebo from the 25th week of pregnancy until the third month of breastfeeding.

The study found that the children whose mothers had taken fish oil supplements had “considerably fewer allergic reactions” than those whose mothers who had taken the placebo. Significantly, they had less than half as many reactions to eggs, which is an early indicator of eczema and asthma.

One of the researchers in the study commented that fish oil worked by relieving inflammation in the mother, and this had an effect on the child’s immune system also.
Source: Omega 3 Fats Appear to Aid Against Child Allergies