Study purpose were to describe growth patterns of premature infants in weight, length and head circumference from birth to 40th week of corrected ages (CA) and to explore factors affecting patterns.

A longitudinal descriptive study was conducted with 267 premature infants. They were categorized into 2 groups; GA group with measurements at birth and the CA group with measurements at CA, which was categorized into 3 groups (group 1-3) by WHO guideline for gestational age (GA) at birth.

GA group presented greater measures in all than CA group at same week of life. Among CA groups, group 3 showed the highest measurements, up to 37 weeks of life, though this disappeared at 38-40 weeks. Reversely, group 1 revealed the highest growth rates in all measures, followed by group 2 and group 3. Significant interaction was observed in all measures between week of life and any type of groups.

Higher measures in GA group, as well group 3 among CA groups, supported the superiority of intra-uterine environment overriding quality of regimen from NICU. Regardless of growth acceleration, smaller infants remain smaller, indicating that intra-uterine thrifty phenotype may continue at least up to the 40th week of CA.