Explainer · Nutrition & Diet
Egg allergy fell in Melbourne babies after guidelines moved egg earlier, in tests of 7,209 infants
Parents were once told to hold off on egg. After Australian guidelines changed to recommend introducing it earlier, fewer one-year-olds tested allergic, with the biggest drop in babies with eczema.
- Researchers compared two groups of Melbourne one-year-olds, tested in 2007 to 2011 and in 2018 to 2019.
- Between them, guidelines changed to recommend earlier egg, and the typical age of first egg fell from 8 to 6 months.
- Egg allergy, confirmed by skin and eating tests, fell from 9.2% to 7.6% after adjusting for risk factors.
- In babies with early eczema, egg allergy fell from 34.6% to 21.9%.
- The groups were different babies years apart, so other changes may have played a part.
For years, parents worried about allergies were told to wait before giving their babies egg. The thinking was that keeping common allergy-causing foods away from a young immune system would protect it. Then the evidence turned that advice around, showing that earlier egg introduction reduces the risk of egg allergy, and guidelines around the world changed to match.
A study in JAMA Pediatrics checked what happened next in Melbourne, Australia. Previously, the evidence came mainly from randomized trials; this study looked at whole populations of one-year-olds before and after the guidelines changed, and found fewer of them allergic to egg.
What egg allergy is
MedlinePlus explains that a food allergy is an abnormal immune system reaction to certain foods. Chicken eggs are on its list of the most common culprits, alongside cow’s milk and peanuts. The reaction is usually mild, but it can sometimes be serious.
Some babies are at higher risk than others. MedlinePlus lists eczema among the factors that raise the risk, describing it as a disease that causes inflammation, redness, and irritation of the skin. The authors note that egg allergy is among the most common food allergies in infants.
How the egg allergy study was designed
The researchers compared two large groups of babies recruited the same way, at their 12-month vaccination visits in Melbourne. The first group was tested in 2007 to 2011 and the second in 2018 to 2019, after the guidelines were updated. In total, 7209 of 9500 eligible infants were included.
The allergy testing was thorough. Infants underwent skin prick tests to egg, and those with positive results underwent oral food challenges, meaning they ate egg in increasing amounts under medical supervision. That is a much firmer test than asking parents whether their child reacted. The team also adjusted the later results so the two groups could be compared as if they had the same mix of known allergy risk factors.
What happened to egg allergy
Parents did change what they did. The typical, or median, age at egg introduction decreased from 8 months to 6 months, a shift of about two months toward the new advice.
Egg allergy fell alongside it. After adjusting for known allergy risk factors, the prevalence of egg allergy decreased from 9.2% in 2007-2011 to 7.6%. The drop was far larger in babies with early eczema, the group at highest risk: from about one in three to about one in five, or 34.6% to 21.9%.
Why the egg guideline result matters
Randomized trials show whether something works in the families who take part. What they cannot show is whether changing national advice actually shifts what happens across a whole population, where parents may not follow it. This study fills part of that gap.
The authors conclude that updated infant feeding guidelines recommending earlier introduction of egg led to measurable reductions in the population prevalence of egg allergy. For babies with eczema, the difference was large enough to matter to many families. Among every 100 such babies, roughly 13 fewer had egg allergy in the later group.
What a before-and-after look at babies cannot prove
The two groups were different babies, tested about a decade apart. Other things may have changed over that time too, and adjusting for known risk factors cannot account for changes nobody measured. That is why a comparison like this can show a drop that fits the guideline change but cannot, on its own, prove the guidelines caused it.
For all babies together, the drop was small and close to the edge of what chance could produce. The eczema result was much clearer. The study took place in one city, with about three in four invited families taking part, and the later group was smaller than the earlier one.
What this changes for feeding babies
For parents, the findings support current advice in many countries to introduce egg in the first year rather than holding it back. For babies with eczema or those who have already reacted to a food, a doctor can advise on how and when to start.
For public health, the study is an encouraging sign that turning trial evidence into guidelines can change outcomes on a population scale. It would be useful to see whether the pattern holds in other cities and for other allergy-causing foods.
People also ask
What did the study find?
The median age at egg introduction fell from 8 months in 2007-2011 to 6 months in 2018-2019. After adjusting for known allergy risk factors, egg allergy prevalence fell from 9.2% to 7.6%, an absolute difference of 1.6 percentage points. In infants with early eczema, it fell from 34.6% to 21.9%, a difference of 12.7 percentage points.
How was egg allergy confirmed?
Babies had a skin prick test to egg, and those with a positive result then had an oral food challenge, meaning they ate egg in carefully increasing amounts under medical supervision to see if they reacted.
Why did the guidelines change?
Evidence, including from randomized trials, found that introducing egg earlier reduced the risk of egg allergy. Allergy prevention guidelines around the world were updated to match.
Why were babies with eczema affected most?
Babies with eczema are at much higher risk of food allergy to begin with, so they had the most to gain. Eczema is one of the best-known risk factors for food allergy.
Does this prove the guideline change caused the drop?
Not on its own. The researchers adjusted for known risk factors, but the two groups were different babies tested about a decade apart, and other things may have changed in between.
When should I give my baby egg?
Infant feeding advice in many countries now recommends introducing egg in the first year rather than delaying it. If your baby has eczema or has already reacted to a food, talk to a doctor first. This is general information rather than medical advice.