Methods
This was a retrospective analysis of the medical records
of premature infants born between January 2000 and
December 2005 in a public teaching hospital. Preterm
infants with birth weight (BW) between 500 and 1,499 g
admitted to the neonatal intensive care unit at Hospital
São Paulo were considered eligible. The exclusion criteria
were death ≤ 7 days, major congenital anomalies and
genetic syndrome. The study was evaluated by the Ethics
Committee of the Universidade Federal de São Paulo,
which considered signing the informed consent form
unnecessary.