By avoiding exposure to the food her child is allergic is to -- starting in the third trimester and continuing into the second year of life, say researchers from Royal Prince Alfred Hospital in Camperdown, Australia.
Seven out of 10 babies born to mothers who took avoidance measures had no food allergies vs. 45% of babies whose moms did not follow the doctors' advice, says pediatrician and study leader Velencia Soutter, MD.
That means eliminating the offending food not only from the diet but also from the environment, she says.
"Take peanut allergies, for example. If someone eats a lot of peanuts in your house, there is going to be aerosolized peanut protein in the environment. You need a clean household," Soutter tells WebMD.
Pregnant Moms Given Food Allergy Advice
Soutter says she undertook the study because "parents of kids with food allergies came to us asking, 'What can we do so this doesn't happen again?' They were desperate."
The study involved 274 pregnant mothers of children with peanut, egg, or milk allergies.
"We didn't tell them what to do, but gave them a lot of advice about how to avoid the food [their child was allergic to]. We started in the third trimester so everything would be in place when the baby was born," she says.
The women were also encouraged to breastfeed, which has been shown to protect against the development of allergies in some studies, Soutter says.
About two-thirds of the women followed their advice.
At 1 and 1/2 and 3 years of age, the babies were evaluated for symptoms of allergic disease and given skin prick tests to determine if they showed susceptibility to the same food allergies as their older siblings.
"The results were dramatic," Soutter says.
Thirty percent of babies born to mothers who took avoidance measures had one or more food allergies vs. 55% of babies whose moms didn't take those avoidance measures,
Babies born to mothers who took avoidance measures were less likely to develop symptoms of asthma: Only 11% exhibited symptoms by the age of 3, compared with 43% of babies whose mothers didn't avoid the offending foods.
Robert Wood, MD, director of the division of pediatric allergy and immunology at Johns Hopkins University School of Medicine in Baltimore, tells WebMD that pregnant women should not feel guilty if they do not want to follow avoidance measures.
"I explain to my patients that exposure [to food allergens] in pregnancy seems to be a risk factor in some studies, but the results are not consistent. We don't have the answer," he says.