Influence of Gestational Age on Fibrinolysis from Birth to Postnatal Day 10

Objective To compare components of the fibrinolytic cascade in newborns of gestational age ranging from extreme prematurity to full term, at birth and for the next 10 days, and in their mothers at delivery. Study design We studied 10 extremely preterm neonates, 10 very preterm neonates, 10 moderately preterm neonates, 10 full-term neonates, and their mothers (n = 40). We measured the antigen levels of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitors 1 (PAI-1) and 2 (PAI-2), and thrombin-activatable fibrinolysis inhibitor, as well as PAI-1 activity, in neonates at birth and on postnatal days 3 and 10 and in mothers at delivery. Results On day 10, both PAI-1 antigen and activity were higher in extremely preterm neonates than in full-term neonates (P = .004 and < .0006, respectively), and the t-PA/PAI-1 activity ratio was lower in the extremely preterm and very preterm neonates compared with the full-term neonates (P = .002 and .017, respectively). No significant differences in the fibrinolytic system components were seen among the 4 groups of mothers. Conclusions The development of fibrinolysis suppression in extremely preterm infants within 10 days after birth may contribute to the increased risk of periventricular hemorrhagic infarction in these infants. (J Pediatr 2011;158:377-82).