Design: Multisite randomised controlled trial
Population: 2,137 pregnant women whose unborn child had at least two first-degree relatives with allergic disease
Primary outcome: IgE-mediated egg or peanut allergy in the infant at 1 year
Effect: 7.8% vs 8.4%; RR 0.93 (95% CI 0.69 to 1.26)

The PrEggNut trial randomised 2,137 pregnant women whose unborn child had at least two biological family members with diagnosed allergic disease. One group ate at least six eggs and 60 peanuts a week; the other no more than three eggs and 30 peanuts. The diet ran from before 23 weeks' gestation until four months into breastfeeding. The primary outcome was IgE-mediated egg or peanut allergy in the infant at one year.

Allergy rates were almost identical: 7.8% with the high diet and 8.4% with the standard diet (relative risk 0.93, 95% CI 0.69 to 1.26). Safety measures did not differ. This was a large, well-powered trial in exactly the high-risk families who ask the question most often.

The practical answer for antenatal clinic is now clear. Women do not need to load up on these foods to protect the baby, and there is no reason to restrict them either. The allergy-prevention effort belongs after birth, with timely introduction of egg and peanut into the infant's own diet.

Tell women with a family history of allergy that eating extra egg or peanut in pregnancy does not lower the baby's allergy risk.
Do not advise avoiding egg or peanut in pregnancy or breastfeeding — there is no protective benefit from restriction either.
Point families towards early introduction of egg and peanut into the infant's diet, which is where prevention evidence lies.
The trial enrolled only high-risk families, so the answer applies most directly to the women most likely to ask.

Why it matters

Removes a dietary burden many high-risk mothers take on in the belief that it protects the baby.

The statistics, in plain English

About 8 in every 100 babies developed egg or peanut allergy in both groups. The relative risk of 0.93 is close to 1, and its confidence interval runs from a 31% reduction to a 26% increase, so the trial rules out any large benefit.