Design: Multisite randomised controlled trial
Population: 2,137 pregnant women with a family history of 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 0.69–1.26)

PrEggNut randomised 2,137 pregnant women whose baby had at least two first-degree relatives with allergic disease. From before 23 weeks until four months of breastfeeding, one group ate at least six eggs and 60 peanuts a week; the other kept to no more than three eggs and 30 peanuts.

IgE-mediated egg or peanut allergy at one year occurred in 7.8% vs 8.4% (RR 0.93, 95% CI 0.69–1.26). Safety measures were similar.

The finding matters mainly for what it removes: there is no basis for telling pregnant or breastfeeding women to increase allergen intake. There is also no reason to avoid these foods. Early introduction to the infant, around six months and not before four, remains the strategy with evidence.

Do not advise pregnant or breastfeeding women to eat extra egg or peanut to prevent allergy in the baby.
Equally, do not advise avoiding these foods in pregnancy or breastfeeding.
Advise introducing egg and peanut (as smooth paste, not whole nuts) into the infant's diet from around six months.
In infants with severe eczema or known egg allergy, arrange assessment before peanut introduction.

Why it matters

It removes a piece of plausible but unsupported dietary advice from antenatal care.

The statistics, in plain English

A relative risk of 0.93 with a confidence interval of 0.69 to 1.26 crosses 1.0, so there was no detectable effect. The trial could not exclude a modest benefit or a modest harm, but a large preventive effect is unlikely.