Eating more eggs and peanuts while pregnant does not prevent infant allergies, clinical trial finds
· Medical Xpressby Sanjukta Mondal, Medical Xpress
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Millions of people around the globe might never know the taste of a PB&J sandwich or crème brûlée because of severe peanut and egg allergies. For a long time, avoiding exposure to allergy-causing foods early in life was considered the best way to prevent this, but now this notion has been turned on its head. Scientists believe exposure as early as during breastfeeding might help children build tolerance to these foods.
A team of researchers explored whether a mother consuming large amounts of egg and peanut during pregnancy and early lactation lowers the chance that her baby will develop an allergy to those foods by age 1.
The randomized trial, called PrEggNut, followed more than 2,000 pregnant mothers whose babies were at higher risk of developing allergic disease because of a family history. Half of the women were asked to eat a diet rich in eggs and peanuts, beginning before 23 weeks of pregnancy and continuing until four months after giving birth while breastfeeding.
Eating lots of eggs and peanuts during pregnancy and breastfeeding didn't significantly reduce babies' risk of developing those allergies. By age 1, infants had about the same risk of an egg or peanut allergy whether their mothers ate more of these foods or stuck to a normal diet.
The findings are published in the New England Journal of Medicine.
How early is early enough
A few randomized trials of early infant feeding challenged existing avoidance practices and suggested that introducing allergenic foods early might build tolerance rather than trigger allergies. However, they didn't give scientists a clear timeline for how early one needs to start. Should it be as early as in the womb and during breastfeeding, when the immune system first encounters maternal antigens and dietary proteins?
Some allergy-prone babies already show immune responses to egg by 4 months of age. So current guidelines, which recommend introducing allergenic foods at 4 to 6 months, may already be too late for these babies.
During pregnancy, a fetus swallows food allergens present in the amniotic fluid, and after birth, infants encounter these same proteins again through breast milk. This natural pattern of exposure led researchers to the hypothesis that pregnancy and early lactation might be the window when a baby's immune system first learns to tolerate foods.
More eggs on a plate
To explore this further, the researchers designed a randomized, single-blind trial conducted across Adelaide, Melbourne, Perth and Sydney, Australia. A total of 2,137 pregnant women took part in the PrEggNut trial, with their unborn babies considered at higher risk of developing allergies.
The team randomly divided the mothers into two equal groups and asked them to follow different dietary patterns. Those in the high egg-and-peanut group consumed at least six eggs and 60 peanuts each week, while mothers in the standard-diet group consumed no more than three eggs and 30 peanuts per week.
- Weekly egg intake. Shown are the median weekly egg intake values across the intervention period for each trial group. Credit: New England Journal of Medicine (2026). DOI: 10.1056/nejmoa2605659
- Weekly peanut intake. Shown are the median weekly peanut intake values across the intervention period for each trial group. Credit: New England Journal of Medicine (2026). DOI: 10.1056/nejmoa2605659
When the infants turned 1, researchers tested them for egg and peanut allergies at major children's hospitals. Each baby first got a skin-prick test. If that came back positive, they moved on to a food challenge, where doctors watched closely as the baby ate small amounts of scrambled egg or peanut butter to confirm whether a true allergy was present.
A high-allergen maternal diet during pregnancy and lactation did not result in a significantly lower risk of infants developing an egg or peanut allergy. When the researchers looked at allergy outcomes, 7.8% of infants whose mothers ate more eggs and peanuts developed an egg or peanut allergy, compared with 8.4% in the comparison group.
Egg allergy occurred in 6.2% of infants in the high-intake group versus 7.2% in the standard group, while peanut allergy rates were identical at 2.6% in both groups. Eczema rates were also comparable between the two groups.
The results make it clear that adding extra eggs and peanuts to a pregnancy diet does not protect a baby from developing allergies to them. Going forward, the focus should be on evidence-based infant feeding guidance rather than asking mothers to take on another dietary burden.
Written for you by our author Sanjukta Mondal, edited by Sadie Harley, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.
Publication details
Debra J. Palmer et al, Trial of a Maternal Diet Rich in Eggs and Peanuts to Reduce Infant Allergy, New England Journal of Medicine (2026). DOI: 10.1056/nejmoa2605659
Maria C. Jenmalm, Maternal Allergen Consumption and Infant Food Allergy — Reassurance, Not Prescription, New England Journal of Medicine (2026). DOI: 10.1056/nejme2610158
Journal information: New England Journal of Medicine
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Allergy and immunologyChildren's healthPediatricsCommon illnesses & PreventionObstetrics & gynecologyWomen's health Who's behind this story?
Sanjukta Mondal
Master's in Chemistry. Freelance science journalist and communicator. Published in Chemistry World, BioSpace, and The Hindu. Full profile →
Sadie Harley
BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile →
Robert Egan
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