Serum immunoglobulins in preterm infants: comparison of human milk and formula feeding.

Serum concentrations of immunoglobulins (IgA, IgG, and IgM) were studied in 64 preterm infants with gestational age of 31 to 36 weeks (mean 33.2 weeks), between 1 week and 4 months after birth. Infants were fed solely human milk or formula based on cow's milk. Infants fed formula exhibited significantly higher IgA levels at the age of 9 to 13 weeks than infants fed human milk. Infants given human milk who received more than 60% of their feeding in the hospital from their own mother had significantly higher IgA levels at the age of 3 weeks than did those receiving less than 30% of their feeding from their own mother. At 1 week of age, formula-fed infants with gestational age of 31 to 33 weeks had a significantly lower mean IgG concentration than those with gestational age of 34 to 36 weeks. However, the two term subgroups of infants receiving human milk, had similar mean concentrations of IgG and the value for infants of 31 to 33 weeks of gestation was significantly higher than that for formula-fed infants at the same gestational age. Serum IgM concentrations were similar whether infants were receiving human milk or formula. The formula feeding caused a more rapid maturation of IgA than did human milk. Results suggest that preterm infants may absorb IgA from the milk of their own mothers and that preterm infants with gestational age of 31 to 33 weeks may absorb IgG from human milk.