Early Discontinuation of Cow's Milk Protein Ingestion Is Associated with the Development of Cow's Milk Allergy

Although early supplementation with cow's milk formula (CMF) reportedly increases the risk of cow's milk allergy (CMA) in breast-fed infants, little is known about the association between the timing of CMF discontinuation and subsequent CMA development.To elucidate the relationship between the timing of CMF discontinuation and CMA development in infants who received CMF in the early days of life.Using data from a randomized controlled trial of a birth cohort from 4 Japanese hospitals, we performed a subgroup analysis of participants who ingested CMF in the first 3 days of life. We compared the proportions of participants who developed CMA at age 6 months in those who discontinued CMF ingestion before age 1 month ("DISC <1-month group"), during age 1 to 2 months ("DISC 1-2-month group"), and during age 3 to 5 months ("DISC 3-5-month group") with those who continued CMF ingestion until age 6 months ("continuous group"). The risk ratios (RRs) and 95% CIs for CMA development were calculated.CMA incidence was significantly higher in the DISC <1-month group (n = 7 of 17, 41.2%; RR, 65.7; 95% CI, 14.7-292.5; P < .001), DISC 1-2-month group (n = 3 of 26, 11.5%; RR, 18.4; 95% CI, 3.2-105.3; P = .003), and DISC 3-5-month group (n = 7 of 69, 10.1%; RR, 16.2; 95% CI, 3.4-76.2; P < .001) than in the continuous group (n = 2 of 319, 0.6%).Early CMF discontinuation, particularly in the first month of life, was associated with CMA development in infants who received CMF in the first 3 days of life.