Growth Patterns of Premature Infants Up to 40th Weeks of Corrected Age

Monday, July 11, 2011: 1:45 PM

Youngmee Ahn, PhD, RN
Min Sohn, PhD
Sangmi Lee
Department of Nursing, Inha University, Incheon, South Korea

Learning Objective 1: 1. The learner will be able to understand physical growth patterns of premature infants during early stage of life to 40th weeks of corrected ages.

Learning Objective 2: 2. The learner will be able to describe the relationship between degree of prematurity and physical growth up to 40th weeks of corrected ages.

Purpose: The study were conducted to compare the growth patterns of premature infants in weight (WT), length (LGTH) and head circumference (HC) during time from birth to 40th weeks of corrected ages (CA).

Methods:  In a longitudinal study, 267 premature infants were consecutively recruited in a neonatal intensive care unit (NICU) in Incheon, Korea. Infants born with congenital/genetic/nutritional problems were excluded due to possibility of growth deviation. After IRB approval, WT, LGTH and HC were weekly collected up to 40 weeks of CA. They were categorized into 2 groups; GA group with data at gestational age (GA) and the CA group with data at CA. CA group was categorized into 3 groups by WHO guideline for degree of prematurity; group 1 (n=7) for extreme prematurity; group 2 (n=45) for moderate prematurity; and group 3 (n=215) for mild prematurity at the time of birth. Data were analyzed with α=.05 in two-tails using SPSS 18.0.

Results: GA groups revealed higher WT, LGTH and HC compared to CA group at almost any week of life. Among CA groups, group 3 showed the highest WT, LGTH and HC measurements, followed by group 2 and group 1 up to 37th week of CA, though this pattern disappeared at 38~40th week of CA. Reversely, group 1 revealed the highest growth rate in all measures , followed by group 2 and group 3. Significant interaction was observed in WT, LGTH and HC between week of life and any type of groups.

Conclusion: Higher WT, LGTH and HC in GA groups indicated that intra-uterine environment is the superior for growth than extra-uterine environments regardless of the degree of prematurity. Regardless of acceleration in growth rate, smaller infants remain as smaller, indicating the early catch-up did not happen at least up to the 40th week of to CA.