Effect of Maternal Egg Intake During the Early Neonatal Period and Risk of Infant Egg Allergy at 12 Months Among Breastfeeding Mothers: A Randomized Clinical Trial

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, SETTING, AND 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. TRIAL REGISTRATION: UMIN Clinical Trials Registry: UMIN000027593