Growth patterns of low birth weight preterm infants: a longitudinal analysis of a large, varied sample.

To obtain growth data on a large sample of low birth weight preterm infants, we monitored 608 infants longitudinally in an eight-site collaborative program. Ninety-nine infants weighed less than or equal to 1250 gm at birth, 289 between 1250 and 2000 gm, and 220 infants between 2000 and 2500 gm. Thirty-four percent were white, 52% black, and 14% Hispanic. Weight, height, and head circumference were measured at birth and at 40 weeks and 4, 8, and 12 months of gestation-corrected age on at least 553 infants each time. Descriptive statistics for all growth variables and a body mass index (kilograms per square meter), plotted by sex and birth weight group, demonstrated growth patterns lower than published standards for term infants of the same age and sex. These patterns of growth differed by birth weight group. No catch-up growth was noted by the 12-month examination (gestation-corrected age) for any birth weight group. We conclude that low birth weight preterm infants have different patterns of growth than term infants during the first year of life, even with plotting corrected for gestational age.