Maternal High-Egg-Peanut Diet During Pregnancy Fails to Cut Infant Allergy Risk

For decades, parents and clinicians have searched for modifiable prenatal factors that might reduce the surging rates of childhood food allergy. The hypothesis that maternal dietary exposure to common allergens during pregnancy and lactation could prime fetal immune tolerance is biologically compelling — but a well-powered randomized trial now delivers a sobering answer.

This multisite trial enrolled 2,137 pregnant women, all carrying a child considered high-risk due to at least two biological family members with diagnosed allergic disease. Participants were randomized before 23 weeks' gestation to either a high intake regimen — a minimum of six eggs and 60 peanuts per week — or a standard control diet capped at half those amounts, maintained through pregnancy and four months postpartum during breastfeeding. The primary endpoint was IgE-mediated egg or peanut allergy confirmed at 12 months of age. The result: 7.8% of infants in the high-intake group developed allergy versus 8.4% in the control group — a relative risk of 0.93 that was neither statistically significant nor clinically meaningful (95% CI: 0.69–1.26; P=0.65). Safety profiles were comparable across groups.

This is an important null result that meaningfully narrows a long-standing hypothesis. The LEAP trial (2015) demonstrated that early direct infant exposure to peanut protein dramatically reduces peanut allergy risk in high-risk infants, reshaping feeding guidelines globally. The assumption that maternal dietary manipulation could replicate this via in-utero allergen transfer or breast milk had theoretical support but sparse controlled evidence. This trial, powered at over 2,100 participants across multiple sites, closes that gap with considerable authority. The null finding aligns with the biological reality that breast milk allergen concentrations from maternal diet are substantially lower than those achieved through direct infant feeding. A key limitation is that the trial does not address the LEAP strategy itself — direct early infant allergen introduction remains strongly supported. For high-risk families, these data suggest that maternal dietary modification alone is unlikely to provide meaningful allergy prevention, reinforcing the primacy of the infant's own oral exposure window.