Maternal egg, peanut diet in pregnancy, and associated infant allergy

Increasing maternal egg and peanut consumption during pregnancy and breastfeeding did not reduce egg or peanut allergy in infants at high hereditary risk, according to results of the randomized PrEggNut trial published in the New England Journal of Medicine.¹ At 1 year of age, IgE-mediated egg or peanut allergy occurred in 7.8% of infants whose mothers followed a high egg–peanut diet and 8.4% of those whose mothers followed a standard diet (relative risk [RR], 0.93; 95% CI, 0.69–1.26; P = .65).¹

The trial tested whether earlier allergen exposure, via amniotic fluid and breast milk, could promote tolerance before solids are introduced.¹ Current guidelines already advise against maternal allergen avoidance; PrEggNut suggests deliberately increasing intake adds no protection.¹

PrEggNut trial design and maternal egg and peanut diet intervention

PrEggNut was a multisite, single-blind, randomized controlled trial conducted in 4 Australian cities.¹ From 2018 to 2024, it enrolled 2137 pregnant women at less than 23 weeks' gestation whose fetus had at least 2 first-degree relatives with medically diagnosed allergic disease; women with egg or peanut allergy were excluded.¹ Participants were randomly assigned to eat at least 6 eggs and 60 peanuts weekly (n = 1070) or no more than 3 eggs and 30 peanuts weekly (n = 1067) through 4 months of breastfeeding.¹

The primary outcome, IgE-mediated egg or peanut allergy at 1 year, was confirmed by skin-prick testing and food challenge, with outcome assessors blinded to group assignment.¹ Monthly text surveys showed clear separation in weekly egg and peanut intake between groups.¹

Infant egg allergy, peanut allergy, and eczema outcomes in PrEggNut

Primary outcome data were available for 90.0% of infants, assessed at a median age of 12.9 months.¹ Results were consistent in a per-protocol analysis of women who breastfed to 4 months and adhered to their assigned diet (5.6% vs 6.8%; RR, 0.80; 95% CI, 0.48–1.35).¹

IgE-mediated egg allergy occurred in 6.2% vs 7.2% of infants in the high-intake and standard-diet groups, respectively, and IgE-mediated peanut allergy in 2.6% of each group.¹ Medically diagnosed eczema by 12 months was reported in 42.8% vs 46.2%.¹

Safety outcomes were similar, including maternal or infant serious adverse events (3.6% vs 3.8%) and infant anaphylaxis to egg or peanut (0.5% vs 0.9%).¹

Prenatal allergen exposure and food allergy prevention guidelines

The trial's rationale rested on evidence that egg-specific immune responses can emerge by 4 months of age, before guideline-recommended introduction of allergenic solids, and that food allergens reach the fetus through amniotic fluid and the infant through breast milk.¹

A 2018 meta-analysis found that maternal allergen avoidance during pregnancy or lactation did not reduce allergic disease in children,² and the EAT trial linked infant consumption of 2 g weekly of peanut or egg-white protein to lower prevalence of those allergies.³ PrEggNut matched maternal egg and peanut protein amounts on a similar basis but found no added benefit from boosting exposure through the mother.¹

PrEggNut limitations and implications for infant allergy prevention

Observed allergy prevalence was about 8%, half the 16% used to power the study, and the confidence interval does not exclude a clinically important 30% relative reduction.¹ Participants were not blinded to diet assignment, and the cohort was largely White and university-educated.¹

The authors attributed the lower prevalence partly to updated Australasian Society of Clinical Immunology and Allergy (ASCIA) infant-feeding guidelines, which all families received.¹ A separate Australian cohort found that giving these guidelines to high-risk families was associated with earlier introduction and a lower combined prevalence of IgE-mediated peanut, egg, and cow's milk allergy at 1 year (4.1% vs 12.6%).⁴

For pediatricians, the findings support advising pregnant and breastfeeding patients to eat egg and peanut normally, without restriction or deliberate excess, while focusing prevention on timely introduction of these foods in the infant diet.¹

References:

1. Palmer DJ, Campbell DE, Nanan R, et al. Trial of a maternal diet rich in eggs and peanuts to reduce infant allergy. N Engl J Med. 2026;395(11):1090-1099. doi:10.1056/NEJMoa2605659
2. Garcia-Larsen V, Ierodiakonou D, Jarrold K, et al. Diet during pregnancy and infancy and risk of allergic or autoimmune disease: a systematic review and meta-analysis. PLoS Med. 2018;15(2):e1002507. doi:10.1371/journal.pmed.1002507
3. Perkin MR, Logan K, Tseng A, et al. Randomized trial of introduction of allergenic foods in breast-fed infants. N Engl J Med. 2016;374(18):1733-1743. doi:10.1056/NEJMoa1514210
4. Walker SVM, D'Vaz N, Pretorius RA, et al. Infant diet recommendations reduce IgE-mediated egg, peanut, and cow's milk allergies. J Allergy Clin Immunol Pract. 2025;13(11):3077-3083.e1. doi:10.1016/j.jaip.2025.06.012