THE DEVELOPMENT OF THE COMPLEMENT-SYSTEM AFTER 28 WEEKS GESTATION

Objective: To assess the levels and development of the various complem ent components in preterm infants, particularly among those born befor e 34 weeks' gestation. Subjects and methods: We measured the complemen t system's activities (CH50 and AP50) as well as its various component s (C1q,r,s, C2-C9, Factor B, and properdin) in 25 preterm infants [ges tational age (GA) 28-33 weeks], 35 preterm infants (GA 34-36 weeks), 5 0 full-term newborn infants (GA 37-42 weeks), and 49 healthy adults as control subjects. Results and conclusions: The results of these studi es are: (i) complement levels and activity were significantly reduced in preterm and full-term neonates when compared with adult levels, wit h the exception of C7 which was within the normal range in most infant s. C8 and C9 were the most markedly reduced at all gestational ages. ( ii) Complement levels correlated significantly with gestational age, b ut not with birth-weight, type of delivery, or gender. (iii) Between 2 8 and 33 weeks' gestation, there appeared to be almost no development of the complement system.