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Eating Peanuts While Pregnant May Up Allergy Risk

Study Shows Higher Peanut Sensitivity in Babies Whose Moms Ate Peanuts in Pregnancy
WebMD Health News
Reviewed by Laura J. Martin, MD

Nov. 1, 2010 -- Babies with evidence of food allergies whose mothers ate peanuts during pregnancy may have an increased risk for potentially life-threatening peanut allergies, a new study suggests.

The more peanuts the new mothers in the study ate during their third trimester, the higher their babies’ risk for sensitivity to peanuts, researchers reported.

The findings do not prove that eating peanuts during pregnancy is a risk factor for peanut allergies in the first year or so of life. But they do highlight the need for more studies to answer the question, study researcher Scott H. Sicherer, MD, of New York’s Mount Sinai School of Medicine tells WebMD.

“Our study looked at sensitization, not peanut allergy,” he says. “It is going to be a few years before we know whether these children really do develop true peanut allergies.”

Pregnancy, Peanuts, and Allergies

About one in 100 children has peanut allergies, and there is evidence that the prevalence has grown over the last decade, researchers say.

In an effort to prevent peanut allergies in children, the American Academy of Pediatrics (AAP) briefly recommended that high-risk women avoid peanuts during pregnancy and while breastfeeding.

But this recommendation was based on very limited clinical research and the group rescinded it in 2008, replacing it with a statement noting that the impact of eating or avoiding peanuts during pregnancy remains uncertain.

In the newly published study, researchers assessed peanut allergy risk in 503 babies presumed to be allergic to eggs and/or milk, based on skin-prick test results or the presence of food allergy-related skin rashes.

The children were 3- to 15-months old, and none had been diagnosed with peanut allergies. Blood testing revealed that 140 had a strong sensitivity to peanuts.

Specifically, the blood test measured levels of a protein known as IgE, which are elevated in people with peanut allergies. But not everyone with high IgE levels is allergic, Sicherer says.

Maternal consumption of peanuts during pregnancy was strongly predictive for this sensitivity, the researchers reported.

The study appears in the November issue of the Journal of Allergy and Clinical Immunology.

Avoiding Peanuts: Good for Some, Not Others?

Until more definitive studies are done, Sicherer says there is no reason to revisit the 2008 AAP revised guideline.

“We simply don’t have enough information to tell women they should or should not eat peanuts during pregnancy,” he says.

There is even some evidence that early peanut exposure may lower an at-risk child’s risk for peanut allergies.

It may even be that some at-risk children benefit from early exposure while early exposure increases peanut allergy risk in others, Baltimore pediatrician Elizabeth Matsui, MD, tells WebMD.

She explains that some experts now believe the interaction between genetic factors and environmental ones, such as when certain foods are introduced in the diet, determine susceptibility to allergies and other health conditions.

Matsui is an associate professor of pediatrics and epidemiology at the Johns Hopkins Children’s Center.

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