The study reveals that daily intake of fish oil capsule and probiotic supplements during the certain period of pregnancy and postnatal reduces egg allergy in kids by 30% and eczema by 22% respectively

In one of the largest ever research reports of how a pregnant woman's diet affects her baby's allergy and eczema risk, scientists from Imperial College London assessed over 400 studies involving 1.5 million people.

Dr. Robert Boyle et al. described "Food allergies and eczema in children are a growing problem across the world. Although there has been a suggestion that what a woman eats during pregnancy may affect her baby's risk of developing allergies or eczema until now there has never been such a comprehensive analysis of the data."

The research advises probiotic and fish oil supplements could reduce a child's risk of developing an allergic condition, and these findings need to be considered when guidelines for pregnant women are updated.

The team assessed a host of dietary factors during pregnancy including fruit, vegetable, and vitamin intake, but found no evidence that any of these affected allergies. 

Around one in 20 children are allergic to foods such as nuts, egg, milk or wheat, in the UK. They have been caused by the immune system malfunctioning and over-reacting to these simple foods which lead to symptoms such as rashes, swelling, vomiting, and wheezing.

Around one in five children are affected by eczema in the UK and causes dry, cracked and itchy skin. The causes of eczema and allergies are not fully understood, but allergies are more common in people who suffer from eczema.

In the present study, the team evaluated 28 trials of probiotic supplements during pregnancy, involving around 6,000 women. Probiotics contain a bacterium called Lactobacillus rhamnosus that may influence the natural balance of bugs in the gut.

Previous research has linked a disruption in naturally-occurring bacteria to allergy risk. And the results were found to reduce the risk of a child developing eczema – between the ages of six months to three years – by 22%.

The team also assessed around 19 trials of fish oil supplements, the capsules contained a standard dose of omega-3 fatty acids during pregnancy, containing approximately 15,000 people. These studies revealed a 30 % reduction in risk of egg allergy by age one. Egg allergy was tested with a skin test, where a tiny amount of egg is pricked onto the skin.

The team also found that taking fish oil supplements during pregnancy reduced the child's risk of peanut allergy by 38 percent. However, they caution this finding was based only on two studies, and not as reliable as the egg allergy and eczema results.

The present study supports a relationship between maternal diet and risk of immune-mediated diseases in the child. Maternal probiotic and fish oil supplementation may reduce the risk of eczema and allergic sensitization to food, respectively.