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High Maternal Egg and Peanut Intake During Pregnancy Does Not Reduce Infant Allergy Risk
A large randomised controlled trial found no meaningful reduction in IgE-mediated egg or peanut allergy at one year of age among infants born to mothers who consumed high amounts of these foods during pregnancy and early lactation, compared with mothers on a standard lower-intake diet (7.8% vs. 8.4%; RR 0.93, 95% CI 0.69–1.26; P = 0.65). The effect size was negligible and the confidence interval spans values from a modest reduction to a modest increase, indicating the result is consistent with no beneficial effect.
What Was Studied
The trial investigated whether substantially increasing maternal dietary intake of eggs and peanuts — two common allergenic foods — during pregnancy and breastfeeding could reduce the likelihood of IgE-mediated egg or peanut allergy in high-risk infants by one year of age. The central hypothesis was that allergen exposure transmitted in utero and through breast milk might prime tolerogenic immune responses before infants begin eating solid foods.
How It Was Studied
This was a multisite, parallel-group randomised controlled trial conducted in Australia. Eligible participants were pregnant women whose unborn child had at least two biologic family members with a medically diagnosed allergic disease, representing a population at elevated familial risk for atopic conditions. A total of 2,137 participants were enrolled and assigned in a 1:1 ratio to one of two dietary regimens beginning before 23 weeks of gestation and continuing through four months postnatally during lactation. The intervention group consumed a diet rich in eggs and peanuts — at least 6 eggs and 60 peanuts per week — while the comparator group followed a standard diet capped at no more than 3 eggs and 30 peanuts per week. Infant allergy status was assessed at 12 months of age.
What Was Observed
- No significant difference in the primary outcome: The rate of IgE-mediated egg or peanut allergy at one year was nearly identical between groups — 7.8% (83 of 1,066) in the high-intake group versus 8.4% (89 of 1,064) in the standard-diet group. This translates to approximately 7% lower relative risk that was not statistically significant (RR 0.93, 95% CI 0.69–1.26; P = 0.65), meaning the observed difference is well within the range expected by chance.
- Confidence interval excludes a clinically meaningful benefit: The upper bound of the confidence interval (1.26) indicates that a meaningful harm cannot be ruled out, while the lower bound (0.69) indicates that at best a modest 31% relative risk reduction is plausible — but this was not the observed point estimate, and the trial cannot confirm it.
- Safety profile was comparable across groups: No differential safety concerns were identified between the high-intake and standard-diet groups, suggesting that the higher maternal allergen intake was well tolerated over the study period.
Why This Matters
The trial directly tests a strategy that has attracted considerable clinical interest: using the maternal diet during pregnancy and lactation as a vehicle for early allergen exposure in offspring considered at high familial risk. The null result challenges the premise that this route of exposure is sufficient on its own to meaningfully reduce infant food allergy, suggesting that in utero and breast-milk-mediated allergen transmission — at least at the doses tested — does not confer the protective immunological priming the hypothesis predicted.
How to Read This Result
This was a well-powered, high-quality multisite RCT with a clear null result; however, uncertainty remains about whether outcomes might differ according to the timing of subsequent solid food introduction, individual variation in allergen levels transmitted through breast milk, or genetic subgroups that were not separately analysed in the reported findings.
Limitations
The abstract does not explicitly report study limitations.