Pregnancy is a time filled with dos and don'ts. Do take folic acid. Don't smoke. Do get daily exercise. Don't take super-hot baths.
When it comes to your diet, you face a laundry list of advice. Until recently, that advice included a caution about potentially allergy-inducing foods. In 2000, the American Academy of Pediatrics advised allergy-prone moms to avoid peanuts and tree nuts during pregnancy to help prevent their babies from getting allergies. They extended the warning to breastfeeding, adding cow's milk, eggs, and fish to the list.
But times have changed, and so has the thinking about allergy prevention. "The incidence of food allergies, particularly peanuts, has increased since those recommendations," says Frank R. Greer, MD, professor of pediatrics at the University of Wisconsin. "The idea of avoiding peanuts was based on deduction, but it seems like that wasn't a good idea."
Published medical studies find no evidence that avoiding foods like milk and eggs during pregnancy has any effect on a baby's allergy risk, and little evidence that shunning peanuts helps.
"Mothers don't need to avoid any of these allergic foods. If anything, they might be beneficial," Greer says. One recent study found that non-allergic mothers who ate peanuts or tree nuts five times a week or more were less likely to have a baby with a nut allergy. The new thinking is that introducing foods early might help an infant build a tolerance to them, lowering the risk of allergies.
Still, if you've got a strong family or personal history of allergies (at least one immediate relative, such as a parent or sibling, with an allergy), your infant is likely high-risk. Talk to your OB/GYN or allergist before you dip into the peanut brittle. There's enough uncertainty in the research to justify caution, at least when it comes to nuts.
What else can you do during pregnancy to cut your child's risk of getting food allergies? Studies show some evidence that taking probiotics ("good" bacteria such as those found in yogurt) late in pregnancy and while breastfeeding may lessen allergies in your baby. The research isn't solid enough to recommend that every pregnant woman take probiotics, but there's probably no harm in trying a supplement if your doctor says it's OK.
Expert Tip
"I ate a well-rounded, balanced diet including cow's milk, eggs, and nuts during my pregnancy. Thankfully, my children are allergy-free. However, I don't have a 'high risk' family history of allergies that could increase my children's risk." -- Nivin C.S. Todd, MD
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