Milk allergy in the neonatal intensive care unit: comparison between premature and full-term neonates

Abstract

Background: There have been several reports on neonates with milk allergy in a neonatal ward. This type of allergy is mostly categorized as a non-IgE-mediated food allergy. Although most cases of milk allergy occur in the first few months of life, the differences in clinical characteristics between premature and full-term neonates are still unclear.

Objective: This study aimed to clarify the differences in clinical characteristics of milk allergy between premature and full-term neonates.

Methods: We retrospectively evaluated 2,116 neonates admitted to the Department of Neonatology, Chiba Kaihin Municipal Hospital, between 2001 and 2007.

Results: We identified 24 neonates strongly suspected of having milk allergy because of symptoms, such as bloody stools, repeated vomiting, diminished sucking and abdominal distension, as well as objective laboratory findings of eosinophilia in stool cytology and/or positive results for a rectal milk challenge test. Twelve of these 24 neonates were premature (median gestational age, 31 ± 3 weeks; median birth weight, 1,656 ± 592 g) and the other 12 were full-term (median gestational age, 38 ± 1 weeks; median birth weight, 2,760 ± 560 g). There were no differences in symptoms and time to start of feeding between premature and full-term neonates, but there was a significant difference in the median postnatal age at onset (premature neonates: 23 days; vs. full-term neonates: 3.5 days; p < 0.01).

Conclusion: All premature neonates developed a milk allergy after 32 weeks of corrected gestational age, suggesting that the development of milk allergy requires a certain degree of immunological maturation.

Keywords: Immune maturation; Milk allergy; Neonates; Onset; Prematurity; Term.

Fig. 1

Postnatal age at onset of premature and full-term milk allergic patients. Premature milk allergic patients had a significantly higher postnatal age at onset than full-term milk allergic patients (13.6 ± 14.5 days for premature milk allergic patients [N = 12] and 5.1 ± 4.8 days for full-term milk allergic patients [N = 12]; Mann-Whitney U test; p < 0.01).

Fig. 2

Effect of gestational age on time of onset in premature milk allergic patients. □ indicates each of premature milk allergic patients. (A) Relation between postnatal age at onset of milk allergy and gestational age. There was a significant negative correlation between postnatal age at onset of milk allergy and gestational age for premature patients (Spearman r = -0.65; p < 0.05). (B) Age at onset of milk allergy by corrected gestational age and gestational age. Premature patients developed milk allergy after 32 weeks of corrected gestational age.