Development of serum IgA and IgM levels in breast-fed and formula-fed infants during the first week of life

Background: IgA and IgM antibodies play important roles to protect infants in early life. Aim: To study the effects of breast milk feeding versus formula feeding in early infancy on the development of serum IgA and IgM. Methods: A group of 220 healthy infants born after uncomplicated pregnancies and deliveries were enrolled. The infants were divided into three groups according to feeding type: breast-fed (BF), formula-fed (FF), and mixed-fed (MF). Capillary blood was collected for serum IgA and IgM detection at the first week of life. Results: The average concentrations of serum IgA and IgM in all infants were 1.171 ± 1.079 and 256.2 ± 165.8 μg/ml, respectively. There were significantly higher concentrations of serum IgA in the FF group than MF group at 3, 4 and 6. days of age and BF group at 5 and 6. days old. Paired serum IgA concentrations revealed that IgA significantly decreased in the BF group, but not in the FF and MF groups. Meanwhile, paired serum IgM concentrations revealed that IgM increased significantly during early infancy in all groups. However, the IgM levels had no difference among the 3 groups within 7. days of age. Conclusions: Our study demonstrated the development of serum IgA and IgM in early life. Formula feeding induced higher serum IgA concentrations than breast-feeding within 7. days of age. However, serum IgM concentration was significantly increased in early life in all groups but had no differences between the different feeding types. Breast-feeding may protect antigen loading in early life.