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Published on: August 7, 2017
Timing of Cow's Milk Protein Introduction and Childhood Adverse Reactions to Cow's Milk
Karen M Switkowski1, Emily Oken2, Sheryl L Rifas-Shiman1
1Division of Chronic Disease Research Across the Lifecourse, Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, Mass.
Insights
Introducing cow's milk protein early in infancy, especially before 2 weeks, appears protective against adverse reactions. Consistent early exposure is key for preventing cow's milk allergies.
Area of Science:
- Pediatric Allergy
- Immunology
- Nutritional Science
Background:
- Current guidelines recommend early introduction of allergenic foods, but optimal timing for cow's milk protein introduction (CMPI) is not well-established.
- Cow's milk is a common first allergenic food introduced to infants, often via infant formula.
Purpose of the Study:
- To examine the relationship between the timing of cow's milk protein introduction (CMPI) and formula supplementation after delivery.
- To assess the association with reported cow's milk adverse reactions throughout childhood, including sensitization and IgE-mediated allergy.
Main Methods:
- Utilized the Project Viva cohort in the Boston area, assessing CMPI timing (<2 weeks, 2 weeks-<6 months, ≥6 months) via infancy questionnaires.
- Collected parent-reported cow's milk adverse reactions annually from age 2 to 13 years.
- Analyzed milk sensitization and IgE-mediated milk allergy at age 8 years using multivariable logistic regression, adjusting for covariates and investigating effect modification by breastfeeding and formula supplementation.
Main Results:
- 32% of infants were introduced to cow's milk protein before 2 weeks, 38% between 2 weeks and 6 months, and 30% at 6 months or later.
- Introducing cow's milk protein at ≥6 months was associated with a higher risk of adverse reactions (OR, 2.4) compared to introduction before 2 weeks.
- The lowest overall risk was observed in infants given formula after delivery plus CMPI before 2 weeks. CMPI between 2 weeks and 6 months showed protection in non-formula-supplemented infants.
Conclusions:
- Early and consistent cow's milk protein exposure appears to be protective against adverse reactions to cow's milk.
- The timing of CMPI was not significantly associated with milk sensitization or IgE-mediated milk allergy in mid-childhood.
Background:
Current guidelines emphasize early introduction to potentially allergenic foods, but the optimal timing, amount, and exposure routes for foods other than peanut are not well-established. Cow's milk is often the first allergenic food introduced through infant formulas.
Objective:
To examine timing of cow's milk protein introduction (CMPI), including interaction with formula supplementation after delivery, in relation to reported cow's milk adverse reactions throughout childhood.
Methods:
Among children in the Boston, Mass-area Project Viva cohort, we assessed timing of CMPI (<2 weeks, 2 weeks-<6 months, ≥6 months) with questionnaires administered in infancy. Outcomes were (1) parent-reported cow's milk adverse reactions via annual questionnaires from age 2 to 13 years (n = 1298) and (2) milk sensitization (n = 505) and IgE-mediated milk allergy (n = 491) at age approximately 8 years. We used multivariable logistic regression models adjusted for parental atopy history, delivery mode, gestational age at delivery, child race, and census tract median household income, and investigated effect modification by ever/never breast-fed status and formula supplementation in the delivery hospital.
Results:
A total of 32% were introduced to cow's milk protein at age less than 2 weeks, 38% at age 2 weeks to less than 6 months, and 30% at age 6 months or more. Compared with children with CMPI at age less than 2 weeks, children with CMPI at age 6 months or more had a higher risk of cow's milk adverse reaction at age 2 to 5 years (odds ratio, 2.4 [1.2-4.7]). Children given formula after delivery + CMPI at age less than 2 weeks had the lowest risk overall. Among children not given formula after delivery, CMPI at age 2 weeks to 6 months appeared most protective. Results were similar among ever-breast-fed children. Timing of CMPI was not associated with milk sensitization or IgE-mediated milk allergy in mid-childhood.
Conclusions:
Early, consistent cow's milk exposure appears protective against adverse reactions to cow's milk.
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