OBJECTIVETo observe catch-up growth in height within two years of birth in infants of different sexes, gestational ages, and birth weights with intrauterine growth retardation (IUGR).

METHODSFollow-up was performed on 294 IUGR infants and 300 healthy full-term infants at 4, 6, 9, 12, 15, 18, 21 and 24 months after birth to measure the height, calculate the height increase and compare the two groups with respect to height increase.

RESULTSThe success rates of catch-up growth in height were 72.2% in male infants and 71.5% in female infants (P=0.90), and were 77.4% in preterm small-for-gestational age (SGA) infants and 68.6% in full-term SGA infants (P=0.11). Success rates of catch-up growth in height in infants with birth weights between 1500-2499 g was higher than in those with birth weights of <1500 g and ≥2500 g (P<0.01). The male infants showed significant catch-up growth at 4, 6, 18, 21 and 24 months after birth, while significant catch-up growth was found in female infants at 4, 6, 9, 12 and 21 months after birth. Of the male infants, preterm SGA infants showed significantly greater height increase than the full-term SGA infants at 6 and 9 months after birth. Of the female infants, preterm SGA infants showed significantly greater height increase than the full-term SGA infants at 4 and 18 months after birth. For both male and female infants, height increase at 4 months after birth was significantly greater in those with birth weights of <1500 g than in those with birth weights of ≥2500 g. For male infants, height increases at 4, 6, 18, 21 and 24 months after birth were significantly greater in those with birth weights of 1500-2499 g than in those with birth weights of ≥2500 g. For female infants, height increases at 4, 6, 9, 12 and 21 months after birth were significantly greater in those with birth weights of 1500-2499 g than in those with birth weights of ≥2500 g.

CONCLUSIONSThe catch-up growth in height within two years of birth in infants with IUGR occurs mainly in the first year after birth in female infants, but can be seen in the first six months and the second year after birth in male infants. Preterm SGA infants better catch-up growth than full-term SGA infants, and infants with birth weights of below 1500 g and between 1500-2499 g show better catch-up growth than those with birth weights of ≥2500 g.