Continuously Tracking Growth of Preterm Infants from Birth to Two Years of Age

Abstract

The objective of this study is to provide gender-specific premature infant growth curves that can be incorporated with the 2006 World Health Organization growth standards to continously track weight, head circumference, and length from 22 weeks of gestion through 2 years of age. Gender-specific percentiles of birth weight, head circumference, and length for premature infants admitted to the Vanderbilt neonatal intensive care unit were used to define intrauterine growth curves from 22 to 36 weeks in terms of best-fit functions and LMS coefficients. Multiple regression and analysis of variance was used to compare the 10 th , 50 th , and 90 th percentiles from the Vanderbilt neonatal intensive care unit with the published values for premature infants from eight studies in the United States, Australia, Italy, Israel, Turkey, Sweden, and the United Kingdom. The intrauterine growth curves were combined with the WHO growth curves and growth trajectories based on birth percentiles were generated with Z-scores. Multiple regression and analysis of variance was also used to compare the male and female 50 th percentiles for birth weight from the nine studies. The 50 th percentiles for birth weight, head circumference, and length from the Vanderbilt neonatal intensive care unit are statistically identical with the intrauterine values from the United States, Israel and Turkey. Five studies showed male and female 50 th percentiles for birth weight differing in the 5.6% to 6.7% range. Values from a premature infant from 32w3d to 12 months and birth percentile growth trajectories were plotted on the combined intrauterine and World Health Organization growth curves. The intrauterine curves can be used to describe infants from different countries. The combined intrauterine and World Health Organization growth curves depict the growth continium of the prematurely born infant from a gestational age of 22 weeks to 2 years of age.