Factors affecting survival and outcome at 3 years in extremely preterm infants.

A total of 823 infants born at 28 weeks' gestation or less were admitted to a regional referral unit between 1980 and 1989. Four hundred and sixty five (56.5%) survived to be discharged home. Twenty one subsequently died and two were lost to follow up. Four hundred and forty two (53.7%) were assessed for disabilities at the age of 3 years. Eighty four (19%) had major disabilities, of which 40 (9%) were severe. A further 39 (9%) had lesser disabilities. Three hundred and nineteen (63%) survivors appeared to be functioning normally. Logistic regression showed the likelihood of survival to be independently related to gestational age, birthweight ratio, and more recent year of birth, and inversely related to male sex and ultrasound evidence of cerebral haemorrhage or infarction. The likelihood of later disability in survivors was only independently related to cerebral ultrasound appearances.