Maternal Egg Consumption During Lactation and Risk of Infant Egg Allergy
by Anne Eglash MD, IBCLC, FABM
If a lactating parent eats eggs early postpartum, will that affect the risk of subsequent infant egg allergy?
Egg allergies are common among children, so finding strategies to reduce the risk is important. There is evidence that introducing eggs to infants at 4-6 months of age reduces the risk, yet some infants are already allergic to eggs before that first introduction. The authors of this week’s study investigated whether maternal ingestion of eggs in the first 5 days postpartum would introduce egg tolerance early in life and reduce the risk of infant egg allergy at 12 months of age. The authors describe evidence that the amount of egg protein in human milk is miniscule, so early oral introduction would act like low dose oral immunotherapy.
This was a randomized controlled trial done in Japan that included 380 lactating dyads with one of the infant’s parents having a history of allergies. The reason for this inclusion criteria is that children of parents with allergic disease have a higher risk for developing food allergy.
The researchers excluded infants who were: under 37 weeks gestation; admitted to neonatal intensive care; diagnosed with birth asphyxia; birth weight under 2300g; unable to tolerate breastmilk after day 2 of life; or born to mothers who were diagnosed with an egg allergy.
The dyads were randomized to a maternal egg consumption group where the mother ate 1 egg each day from days 0 to 5 postpartum, vs a control group where the mother eliminated eggs from days 0-5 postpartum.
The researchers measured the existence of egg proteins in the breastmilk of mothers in each group on postpartum day 4 and found that the egg protein levels in breastmilk were significantly higher in the egg consumption group. By 1 month postpartum, there was no difference in the among of egg protein in breastmilk between the 2 groups.
Infant blood tests were done at ages 4 and 12 months to measure IgE antibody levels to egg white, as well as other allergens including cow’s milk, casein, wheat, and gluten.
What else? See the question!
- The infants who had eczema at 1 month of age had a higher risk of egg allergy at 12 months.
- Eczema rates at 4 months of age were higher among the infants exposed to egg protein via breastmilk in the first 5 days of life.
- After maternal egg consumption, the egg protein levels in milk peaked at 12 hours and remained high for 72 hours.
- After maternal egg consumption, the egg protein levels in milk peaked at 3-6 hours.
See the Answer
Abstract
Importance
Egg introduction in infants at age 4 to 6 months is associated with a lower risk of immunoglobulin E–mediated egg allergy (EA). However, whether their risk of EA at age 12 months is affected by maternal intake of eggs at birth is unknown.
Objective
To determine the effect of maternal egg intake during the early neonatal period (0-5 days) on the development of EA in breastfed infants at age 12 months.
Design, Settings, Participants
This multicenter, single-blind (outcome data evaluators), randomized clinical trial was conducted from December 18, 2017, to May 31, 2021, at 10 medical facilities in Japan. Newborns with at least 1 of 2 parents having an allergic disease were included. Neonates whose mothers had EA or were unable to consume breast milk after the age of 2 days were excluded. Data were analyzed on an intention-to-treat basis.
Interventions
Newborns were randomized (1:1) to a maternal egg consumption (MEC) group, wherein the mothers consumed 1 whole egg per day during the first 5 days of the neonate’s life, and a maternal egg elimination (MEE) group, wherein the mothers eliminated eggs from their diet during the same period.
Main Outcomes and Measures
The primary outcome was EA at age 12 months. Egg allergy was defined as sensitization to egg white or ovomucoid plus a positive test result in an oral food challenge or an episode of obvious immediate symptoms after egg ingestion.
Results
Of the 380 newborns included (198 [52.1%] female), 367 (MEC: n = 183; MEE: n = 184) were followed up for 12 months. On days 3 and 4 after delivery, the proportions of neonates with ovalbumin and ovomucoid detection in breast milk were higher in the MEC group than in the MEE group (ovalbumin: 10.7% vs 2.0%; risk ratio [RR], 5.23; 95% CI, 1.56-17.56; ovomucoid: 11.3% vs 2.0%; RR, 5.55; 95% CI, 1.66-18.55). At age 12 months, the MEC and MEE groups did not differ significantly in EA (9.3% vs 7.6%; RR, 1.22; 95% CI, 0.62-2.40) or sensitization to egg white (62.8% vs 58.7%; RR, 1.07; 95% CI, 0.91-1.26). No adverse effects were reported.
Conclusions and Relevance
In this randomized clinical trial, EA development and sensitization to eggs were unaffected by MEC during the early neonatal period.
The researchers for this study hypothesized that early exposure to egg protein in the first 5 days of life would decrease the risk of infant egg allergy at 12 months of life because the early exposure would induce tolerance. However, there was no difference in egg allergy in these 2 groups at 12 months of age. They found that 62.8% of the infants in the intervention group showed sensitization to egg white at 12 months of age, vs 58.7% among the control group, a difference that was not significant.
There was no difference in rates of eczema in the 2 groups, although the infants with eczema were more likely to be diagnosed with egg allergy.
Interestingly, among the mothers who consumed 1 egg for the first 5 days postpartum, only 10.7% had detectable egg protein in their milk on day 4 when egg protein levels were measured at 1 hour, 3 hours and 6 hours after ingestion. This may be a reason why there was no difference in rate of egg allergy at 12 months.
There are likely several factors that determine transmission of maternal food proteins into breastmilk. They hypothesized that the mothers needed to eat more food protein, or for a longer time to induce tolerance to egg starting from birth. Among those who had measurable egg protein in their milk, the protein levels peaked at 3-6 hours after ingestion.