[Dynamic evaluation on body weight gain in premature infants and its significance]

To investigate the incidence of intra- and extrauterine growth retardation (EUGR) and growth restriction in premature infants, and to illustrate the growth pattern of them in postnatal and infantile period.

All premature infants were admitted to our neonatal intensive care unit (NICU) during the recent 7 years. The criteria for enrollment were (1) gestational age < 37 weeks; (2) single fetus; (3) admitted within the first 24 hours of life; (4) hospitalization period ≥ 14 days; (5) clinical follow-up persisted till ≥ 3 months of corrected gestational age. Intrauterine growth restriction (IUGR), EUGR and growth restriction were defined as having a measured growth value (weight) that was ≤ 10(th) percentile of Chinese infants' growth curve in corrected age on admission, discharge and follow-up period. Results were analyzed by using SPSS 12.0 statistical software package by chi-square test, rank-sum test, and t test.

Two hundred and thirty nine infants were involved, 134 were boys and 105 girls. The incidence of IUGR and EUGR assessed by weight was 25.5% and 40.6%, respectively. The lower the birth weight was, the higher the incidence of IUGR and EUGR was. The percentile of body weight in the growth curve at discharge was lower than that at birth (Z = -7.784, P = 0.000). The incidence of growth restriction assessed by weight was 20.5%, 15.0%, 8.8%, 17.0%, 10.4%, 10.1%, 11.9%, 7.0% at corrected gestational age of 38 - 40 weeks, corrected age of 28 d, 61 d, 91 d, 122 d, 152 d, 183 d, and 274 d, respectively. The incidences of growth restriction were stable when the corrected age was older than 91 days. The incidence of growth restriction in female premature infants at 183 days' corrected age was higher than that in male children (χ(2) = 6.181, P = 0.017), the incidence was 19.3% and 3.8% respectively. During the follow-up period, most of the average body weight of premature infants whose gestational age was < 32 weeks or birth weight ≤ 1500 g were lower than the 50(th) percentile of the growth curve except the average body weight of boys whose gestational age < 32 weeks at corrected age of 2 and 4 months.

Premature and/or low birth weight infants are at high risk of growth restriction, especially very low birth weight infants. The incidence of growth restriction decreased with growth. Long-term prognosis requires further investigation.