Do eggs and peanuts in pregnancy prevent baby allergies?
No. Loading up on eggs and peanuts in pregnancy did not prevent infant allergy in this 2,137-woman trial, where 7.8% of babies in the high egg-peanut group and 8.4% in the standard-diet group had an egg or peanut allergy at age 1.
The idea being tested here is an appealing one. If a baby’s immune system meets a food allergen early, before it has a chance to treat that food as a threat, maybe it learns to tolerate it. The earliest possible exposure would happen before birth, through the placenta, and then through breast milk. The trial’s authors put the reasoning plainly: immune responses leading to food allergy “may develop early in life, potentially before the introduction of solid foods.”
The reasoning is not new, but until now it rested on theory. Feeding allergens to the baby in the womb and through breast milk has been proposed as a prevention strategy for years, and the authors note that evidence from randomized trials is lacking. This trial set out to supply it.
What the data show
Researchers randomly assigned 1,070 pregnant women to a high egg and peanut diet and 1,067 to a standard diet. By the time their babies turned 1, IgE-mediated egg or peanut allergy had been diagnosed in 83 of 1,066 infants in the high egg-peanut group and 89 of 1,064 in the standard-diet group.
In relative terms that works out to about a 7% lower risk (relative risk 0.93), which sounds like something until you look at the absolute numbers. The gap was 0.6 percentage points, or about 6 fewer allergic babies per 1,000. The range of effects still compatible with the data runs from 31% lower risk all the way to 26% higher risk (95% confidence interval 0.69 to 1.26), so this trial cannot even tell you which direction the true effect points. A difference this small would show up by chance roughly 65 times out of 100 (P = 0.65). That is about as clean a null result as a trial can produce.
Dr. Kumar’s Take
A well-run trial that finds nothing is still a useful trial, and this is a good example. Two thousand women is a serious sample, the outcome was a diagnosed IgE-mediated allergy rather than a parent’s report, and the two diets were clearly different from each other. When a study is built that well and the two groups still land on top of each other, the honest read is that the intervention does not work.
What this does not say matters just as much. The standard-diet group was not an avoidance group. Those mothers still ate up to 3 eggs and 30 peanuts a week, so the finding is that eating extra buys no protection, not that eating less is fine. And the trial intervened only on the mother, from before 23 weeks of pregnancy through 4 months of breastfeeding. It never touched what the baby ate afterward, so prenatal loading and infant feeding remain two different questions.
Study snapshot
This was a multisite randomized trial, funded in part by the Australian National Health and Medical Research Council and registered as PrEggNut. Enrollment was deliberately limited to high-risk pregnancies: a woman was eligible only if her unborn child had at least two biologic family members with medically diagnosed allergic disease. Those are exactly the babies you would expect to benefit most from any real protective effect, which makes the null result harder to explain away.
Women were assigned in a 1 to 1 ratio to either the high egg-peanut diet, at least 6 eggs and 60 peanuts per week, or the standard diet of no more than 3 eggs and 30 peanuts per week. The primary outcome was set in advance: IgE-mediated egg or peanut allergy in the infant at 1 year of age.
Safety, limits, and caveats
Safety measures were similar in the two groups. Eating 6 eggs and 60 peanuts a week through pregnancy and the early months of breastfeeding did not produce a signal of harm, it simply did not produce a benefit either. Two limits are worth holding onto. Follow-up stopped at 1 year, so nothing here speaks to what happens to these children later. And the population was high-risk by design, with roughly 8 in 100 babies developing an egg or peanut allergy in both groups, so whether the same diet does anything in families with no allergy history was not tested.
Practical takeaways
- If you are pregnant and have been eating extra eggs or peanuts specifically to protect your baby from food allergy, eat them for their nutrition instead, because this trial shows that strategy does not deliver.
- Do not read this as a reason to cut eggs or peanuts out during pregnancy, because the comparison group still ate up to 3 eggs and 30 peanuts a week and safety measures were similar in both groups.
- If allergic disease runs in your family, talk with a pediatrician or allergist about the infant feeding plan after birth, since that is a separate question this trial did not test.
Related Studies and Research
- Does replacing saturated fat with linoleic acid reduce heart disease risk?
- Mediterranean diet with olive oil or nuts reduces heart disease risk: a landmark study
- Purine-rich foods, dairy, and protein intake: how diet shapes gout risk in men
- Does vitamin D supplementation reduce heart disease risk?
FAQs
Should pregnant women avoid eggs and peanuts instead?
Nothing in this trial points that way. The comparison group was not an avoidance group, it was a normal-eating group that still included up to 3 eggs and 30 peanuts a week, and about 92 in 100 of those babies had no egg or peanut allergy at 1 year. The trial compared “a lot” with “a normal amount,” so it has nothing to say about zero. Safety measures were similar in both arms, which means the higher intake was tolerated even if it did not help.
Does this apply to families with no history of allergies?
Not directly. Every woman enrolled had an unborn child with at least two biologic family members carrying a medically diagnosed allergic disease, and that is a much higher baseline risk than the general population. Researchers often pick high-risk groups on purpose, because an effect is easiest to detect where the outcome is common. A diet that fails to help the highest-risk babies is unlikely to be doing much in lower-risk ones, but this trial did not measure that group.
Is one year long enough to judge an allergy outcome?
The 1-year mark was chosen and locked in as the primary outcome before the trial started, which is exactly how a trial should be designed, so the result is not a number someone went looking for after the fact. It is still a snapshot. Food allergies can change through childhood, and this trial reported the 1-year result, so anything beyond that age remains an open question. That is a reason to watch for longer follow-up from the same group, not a reason to discount the 1-year finding.
Bottom Line
In a randomized trial of 2,137 pregnant women carrying babies with a strong family history of allergy, eating at least 6 eggs and 60 peanuts a week from before 23 weeks of pregnancy through 4 months of breastfeeding did not lower the rate of egg or peanut allergy at age 1. The rates were 7.8% and 8.4%, a difference of about 6 per 1,000 that the trial could not separate from chance. Prenatal allergen loading is not a prevention strategy, and the answer to infant food allergy has to be looked for somewhere other than the mother’s plate.
