Natural history of serum immunoglobulin concentrations in low birth weight infants and association with respiratory tract infections.

UNLABELLED: Infections are a significant cause of morbidity and mortality among low birth weight (LBW) infants. THE AIMS OF OUR STUDY WERE: (1) to investigate whether serum antibody concentrations in 62 LBW infants (1,500-2,500 g) were normalized by 1 year of life, and (2) to determine the clinical relevance of humoral immaturity in these children during the 1st year compared to 20 appropriate-for-gestational-age (AGA) term infants. At 1 year of life, immunoglobulin serum concentrations in LBW infants were comparable to those of the control group. The incidence of respiratory tract infections during the 1st year of life was not significantly different between LBW and AGA term infants. Interestingly, we demonstrated that LBW infants with a higher frequency of reported febrile upper respiratory tract infections had more elevated serum total IgG, IgG(1), IgG(3), total IgA, and IgA(1) concentrations. Thus, infants with a birth weight of 1,500-2,500 g do not appear to have an increased risk of respiratory tract infections compared to AGA term children during the 1st year of life. Furthermore, our data suggest that especially febrile infections induce higher serum immunoglobulin concentrations in LBW infants. Copyright 2002 S. Karger AG, Basel