Different Catch-Up Growth Patterns in Very Preterm and Small for Gestational Age Infants

This study aimed to describe the growth pattern in preterm infants and identify factors influencing catch-up growth. A total of 288 preterm infants were divided into groups based on the degree of prematurity, sex, and size for gestational age. Growth in head circumference, length, weight-for-length, and weight was compared between groups at corrected age of 0, 3, 6, 9, 12, 18, and 24 months. Logistic regression analysis was conducted to determine risk factors for catch-up growth. At a corrected age of 24 months, the proportions of preterm infants with z-scores less than -2 for head circumference, length, weight-for-length, and weight were less than the expected 2.3% at 0.9%, 1.7%, 2.1%, and 1.7%, respectively. The head circumference, length, weight-for-length, and weight z-scores at corrected ages of 24 months were lower in the small for gestational age (SGA) group than in the non-SGA group (P < .05). The weight-for-length z-scores were higher in the late preterm birth infants than in the very preterm birth infants at a corrected age of 24 months (P < .05). At a corrected age 24 months, the proportion of male with weight z-scores <-2 was lower than that of female (P < .05). The differences in proportion of the z-scores (head circumference, length, weight-for-length, and weight) <-2 at a corrected age of 24 months among different gestational age groups and intrauterine growth status groups were not statistically significant (P > .05). We found that the factors influencing catch-up growth in preterm infants varied at different corrected age stages, and the impact of factors during hospitalization gradually diminished as the infants grew.