Preterm infants were excluded if: a) they had congenital malformations, chromosomal
aberrations, congenital infections, genetic anomalies, congenital heart
malformations, and/or central nervous system dysfunction (e.g., intraventricular
hemorrhage or a history of seizure); b) they were HIV positive;
c) had a history ofmaternal alcohol/illicit drug use (as determined
by the mother's reported history, medical records, and universal drug
screen performed prior to delivery), syphilis, or hepatitis B, or d) they
required surgery. All infants were bottle-fed premature infant formula.
Infants were stratified based on gender, birth weight, gestational age
at birth, and days on the NICU prior to group assignment