Six eggs and 60 peanuts a week in pregnancy did not reduce infant allergy in a 2,137-woman trial
A 2,137-woman randomized trial in the New England Journal of Medicine found that eating at least six eggs and 60 peanuts a week during pregnancy and breastfeeding left infant egg-or-peanut allergy at the same rate as eating little of either, so ordinary intake is enough and there is no reason to cut these foods out.
Women who ate at least six eggs and 60 peanuts every week during pregnancy and the first four months of breastfeeding finished the trial period with the same rate of infant egg or peanut allergy as women who ate little of either. PrEggNut randomized 2,137 pregnant women, all of them carrying a child with a strong family history of allergic disease, and followed the babies to their first birthday. 1
At 12 months, food-challenge-confirmed egg or peanut allergy affected 7.8% of the infants in the high-intake group and 8.4% in the standard-diet group, a relative risk of 0.93 with a 95% confidence interval of 0.69 to 1.26. 1
That single comparison settles two competing pieces of kitchen-table advice at once. Eating extra allergens to protect a baby does not work. Eating these foods normally, as almost everyone already does, carries no penalty.
What the women in the trial actually ate
PrEggNut ran at hospitals in Adelaide, Perth, Sydney and Melbourne, and enrolled women before 23 weeks' gestation. A woman qualified if she had a single pregnancy, planned to breastfeed for at least four months, and had at least two biological family members — the baby's mother, father or sibling — with a doctor-diagnosed allergic disease: asthma, eczema, hay fever or IgE-mediated food allergy. Women who were themselves allergic to egg or peanut were left out, because the assigned diet would have been unsafe for them. 2
Every participant already ate eggs and peanuts. The standard-diet arm was told to stay at or below 3 eggs and 30 peanuts a week, which matches ordinary Australian intake: 899 postpartum women surveyed at one of the recruiting hospitals averaged 2.5 eggs and 20 peanuts a week. The high-intake arm was asked to reach at least 6 eggs and 60 peanuts. Both targets sit inside the Australian dietary guidelines for pregnancy, which recommend 2.5 to 3.5 serves a day of protein foods such as lean meat, poultry, fish, eggs, nuts, seeds and legumes. 2
Women followed the assigned diet from before 23 weeks' gestation until their baby turned four months old, and answered four questions about their egg and peanut intake every month. 2
The outcome was the strictest one available. Every infant with a positive skin-prick test to egg or peanut at 12 months went on to a supervised hospital food challenge — lightly cooked scrambled egg or peanut butter — scored to the Australasian Society of Clinical Immunology and Allergy standard. A positive test on its own did not count as allergy. 2
What the one-year numbers showed
| Arm | Weekly egg and peanut intake | Infants analysed | Egg or peanut allergy at 12 months | What the number means in practice |
|---|---|---|---|---|
| High egg-and-peanut diet (1,070 women assigned) | At least 6 eggs and 60 peanuts | 1,066 | 83 infants, 7.8% | The extra allergens changed the rate by about half a percentage point 1 |
| Standard egg-and-peanut diet (1,067 women assigned) | No more than 3 eggs and 30 peanuts | 1,064 | 89 infants, 8.4% | Ordinary intake produced the same result as the high dose 1 |
The two food allergies behaved the same way when counted separately: IgE-mediated egg allergy in 6.2% of infants in the high-intake arm against 7.2% in the standard arm (RR 0.87, 95% CI 0.62 to 1.21), and egg or peanut sensitization with the same pattern. Peanut allergy came in at 2.6% in both arms (RR 1.02, 95% CI 0.60 to 1.76). Medically diagnosed eczema was also close: 16.4% against 18.1% at four months, and 42.8% against 46.2% at 12 months. 34
A dietitian weighing whether to trust a null result will want to know what happened in the women who stuck closest to their assignment. The per-protocol analysis, which counts only those women, put the rate at 5.6% against 6.8% (RR 0.80, 95% CI 0.48 to 1.35). That leans the same direction, inside a much wider interval. 34
Safety also matched. Serious adverse events occurred in 3.6% of the high-intake group and 3.8% of the standard group, and anaphylaxis to egg or peanut in 0.5% against 0.9%. 34
Why a high-allergen diet looked promising
Two separate lines of evidence pointed toward maternal diet, and the trial settles only one of them.
The first was observational. A 2014 cohort study followed 8,205 children of women in the Nurses' Health Study II and compared peanut and tree-nut allergy against how often their mothers had eaten those foods around the pregnancy. Among the 8,059 mothers who were not themselves allergic, children of the heaviest nut eaters — five or more times a month — had lower odds of peanut or tree-nut allergy than children of mothers who ate nuts less than once a month (odds ratio 0.31, 95% CI 0.13 to 0.75). 5 A cohort study can show that a mother's diet and her child's allergy travel together. It cannot show that changing the diet changes the allergy, and PrEggNut is the randomized test of that inference.
The second line of evidence concerns what the infant eats, and it holds up. In the LEAP trial, 640 infants with severe eczema, egg allergy or both were assigned either to eat peanut regularly or to avoid it. Among the 530 infants whose skin-prick test was negative at the start, peanut allergy at 60 months reached 13.7% in the avoidance group and 1.9% in the consumption group. 6 The PETIT trial gave heated egg in small increasing steps to 147 infants with eczema, starting at four to five months, and found egg allergy in 8% of the egg group against 38% of the placebo group. 7 Both results changed infant feeding guidance rather than maternal guidance.
That is where the PrEggNut authors place their own finding: the maternal null result, they write, "reinforces the importance of timely introduction of egg and peanut in infant diets." 34
What this trial can and cannot rule out
The trial ran in high-risk families only. Every participating fetus had at least two first-degree relatives with allergic disease, and women with their own egg or peanut allergy were excluded. For a woman with no family history of allergy, PrEggNut says even less than it does for the women it enrolled. 2
The endpoint was measured at 12 months. Allergy that appears later in childhood was not part of the comparison.
The primary comparison was also less powered than planned, because fewer babies developed allergy than the researchers expected — roughly 8% instead of the 16% their sample-size calculation used, a figure drawn from data collected before Australia's 2016 infant-feeding update, which began recommending early introduction of allergenic foods. 34 The authors write that the lower event rate "may have reduced our ability to detect an effect of the dietary intervention (although the confidence interval does not rule out the possibility of a clinically important 30% risk reduction)." In the accompanying editorial, Maria C. Jenmalm of Linköping University reads the same interval as arguing "strongly against a clinically important preventive effect of high maternal intake." 8
Both arms received advice consistent with current allergy prevention guidance, including introducing egg and peanut in the first year of life. The trial therefore ran in a population already eating these foods early, which is one likely reason the allergy rate came in low. 8
One boundary matters most for practice: PrEggNut compared a large amount of egg and peanut with an ordinary amount. It did not test avoidance, and the standard-diet arm still ate up to 3 eggs and 30 peanuts a week. Nothing in this trial supports taking these foods off a pregnant or breastfeeding woman's plate.
The same-day dietary decision
- Eat eggs and peanuts normally through pregnancy and breastfeeding. The standard-diet arm was the ordinary-intake arm, and its infants did as well as any. If you tolerate these foods, keep them in the rotation. 2
- Cross egg-and-peanut loading off the prevention list. Six eggs and 60 peanuts a week is roughly double the usual intake, and it moved the allergy rate by less than one percentage point. 1
- Direct the prevention effort at the baby's own diet. Introduce egg and peanut when solid foods begin, around six months and not before four, one food at a time and in age-appropriate forms such as well-cooked egg and smooth peanut butter thinned into food, then keep them in the diet. Ask your pediatric team about timing if your baby has severe eczema. 8
- Ask about maternal diet only when the mother cannot eat the food. Women with their own egg or peanut allergy were excluded from this trial, and their situation follows allergy-management advice rather than prevention advice. 2
References
- 1Trial of a Maternal Diet Rich in Eggs and Peanuts to Reduce Infant Allergy, PubMed record
pubmed.ncbi.nlm.nih.gov
- 2PrEggNut trial protocol, BMJ Open
bmjopen.bmj.com
- 3
- 4MedPage Today report on the PrEggNut results
medpagetoday.com
- 5Frazier et al., JAMA Pediatrics, 2014
pubmed.ncbi.nlm.nih.gov
- 6Du Toit et al., New England Journal of Medicine, 2015
pubmed.ncbi.nlm.nih.gov
- 7Natsume et al., The Lancet, 2016
pubmed.ncbi.nlm.nih.gov
- 8
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