Pregnancy diet could influence the development of allergies in early life.
According to BBC Health, fish oil contains a special kind of fat called omega-3 that has a positive, anti-inflammatory effect.
But they said the research confirmed that pregnancy diet could influence the development of allergies in early life.
Allergies are caused by the immune system malfunctioning and over-reacting to these harmless foods, and this triggers symptoms such as rashes, swelling, vomiting and wheezing.
The research suggests probiotic and fish oil supplements may reduce a child's risk of developing an allergic condition, and these findings need to be considered when guidelines for pregnant women are updated.
Pregnant women should eat no more than two portions of oily fish per week due to presence of mercury in some fish.
The researchers who studied past trials by Imperial College London looked at 19 trials of fish oil supplements taken during pregnancy involving 15,000 people.
They found that reduction in allergy risk equated to 31 fewer cases of egg allergy per 1,000 children.
They also looked at the impact of probiotic supplements taken during pregnancy and found a 22% reduction in the risk of eczema developing in children up to the age of three.