Increasing maternal consumption of eggs and peanuts during pregnancy and breastfeeding does not significantly reduce the risk of egg or peanut allergy in infants at 1 year of age, according to a large randomized trial published in the New England Journal of Medicine. Conducted by Australian researchers across Adelaide, Melbourne, Perth, and Sydney, the PrEggNut trial evaluated 2,137 pregnant women to test whether prenatal and lactating dietary interventions could shape infant food tolerance before the introduction of solid foods.
The PrEggNut Trial Design and Dietary Intervention
Study organizers selected women carrying a single fetus at less than 23 weeks of gestation who intended to nurse for a minimum of 4 months, and whose expected baby had at least two biological relatives diagnosed by a doctor with allergic conditions such as eczema, asthma, allergic rhinitis, or IgE-mediated food allergy. Women with pre-existing egg or peanut allergies were excluded from the study. Out of 2,137 enrolled participants, 1,070 women were randomly assigned to a high egg-peanut diet, while 1,067 were assigned to a standard diet.
The high-intake group consumed at least 6 eggs and 60 peanuts per week from enrollment until 4 months after delivery during lactation, or until breastfeeding ceased. Participants in the standard-diet group consumed no more than 3 eggs and 30 peanuts per week, which aligned with typical Australian intake and existing health guidelines that do not recommend avoiding common food allergens during pregnancy or lactation. Periodic tracking via monthly surveys showed that 64.4% of the high-consumption cohort achieved the egg target and 66.6% attained the peanut goal across 75% or more of the evaluation periods. In the standard-diet group, adherence to upper limits was 72.7% for eggs and 79.7% for peanuts.
Allergy Outcomes and Infant Sensitization Results
At a median infant age of 12.9 months, researchers assessed primary and secondary outcomes, including IgE-mediated egg or peanut allergy, skin-prick test responses, and medically diagnosed eczema. Based on the published results, an IgE-mediated peanut or egg allergy developed in 83 out of 1,066 infants (7.8%) belonging to the high egg-peanut group, contrasted with 89 out of 1,064 infants (8.4%) from the standard-diet group. This yielded no statistically significant difference in combined allergy risk.
Did you know?
Fetal immune cells become responsive to allergens around 23 weeks of pregnancy, which is why the PrEggNut trial initiated dietary interventions at that specific gestational milestone.
When researchers restricted the analysis to women who breastfed for 4 months with adequate dietary adherence, allergy rates remained similar at 5.6% and 6.8% in the respective groups. Individual outcomes—including specific egg and peanut allergies, allergen sensitization, and eczema prevalence at 4 and 12 months—showed no notable divergence between the cohorts. Safety outcomes were also comparable, with serious adverse events recorded in 3.6% of the high-intake group and 3.8% of the standard-diet group, while infant anaphylaxis to egg or peanut occurred in 0.5% and 0.9% of infants, respectively.
Trial Limitations and Evolving Allergy Guidelines
The study faced limitations, notably that the actual observed prevalence of egg or peanut allergy was approximately 8%, falling short of the anticipated 16%. The authors noted that this lower incidence may have reduced the statistical power to detect a preventive effect, though confidence intervals do not completely exclude a clinically important 30% reduction in risk.
This lower prevalence likely reflects broader shifts in infant feeding practices following the 2016 update to Australian allergy-prevention guidelines, which recommend the direct introduction of peanut butter and cooked egg during an infant’s first year of life. Separate evidence continues to support the timely, direct introduction of these allergens into the infant diet rather than relying solely on maternal dietary modification during pregnancy and lactation.
Pro Tip:
Current guidelines from the Australasian Society of Clinical Immunology and Allergy do not recommend omitting allergenic foods during pregnancy or nursing, nor do they advise excessive consumption as a guaranteed preventive measure.
Frequently Asked Questions
Did eating more eggs and peanuts during pregnancy prevent allergies?
No. According to the PrEggNut trial published in the New England Journal of Medicine, increasing maternal consumption of eggs and peanuts during pregnancy and lactation did not significantly reduce the risk of egg or peanut allergies in 1-year-old infants.
What amounts of eggs and peanuts did participants consume?
Participants in the high-intake group consumed at least 6 eggs and 60 peanuts per week, while those in the standard-diet group consumed no more than 3 eggs and 30 peanuts per week.
Does the Australasian Society of Clinical Immunology and Allergy recommend avoiding allergens?
No. The Australasian Society of Clinical Immunology and Allergy does not recommend omitting allergenic foods during pregnancy or nursing.
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