[Evaluation of the complement system and immunoglobulin G levels in cord blood. Relationship with gestational age and intrauterine growth]. / Avaliação do sistema complemento e da imunoglobulina G no sangue do cordão umbilical de recém-nascidos. Relação com a idade gestacional e adequação do crescimento intra-uterino.

OBJECTIVE: To evaluate the complement system in cord blood and its relationship with the degree of maturation and intrauterine growth. METHODS: Serum levels of C(3), C(4) and CH(50) were measured in premature, small for gestational age and appropriate for gestational age newborns. The activation of complement system was searched by clivage product determination C(3d) and C(4d). Serum IgG levels were also determined in all children. RESULTS: The levels of C(3), C(4), CH(50) and IgG were significantly lower in preterm (p < 0,001); C(4) and IgG values were also significantly lower in small for date than those in normal newborn. C(3d) and C(4d) were not detected, indicating that the complement system had not been activated. CONCLUSIONS: The lower complement component levels and IgG in newborn are related to gestational age as well as to intrauterine growth.