[Postnatal growth of very low birth weight infants during hospitalization].

OBJECTIVE: To study the postnatal growth of very low birth weight infant (VLBWI) and its relevant influencing factors during hospitalization.

METHOD: Clinical data of very low birth weight infants (VLBWI), who were discharged from July 1(st), 2010 to June 30(th), 2011, were collected retrospectively from 9 NICUs of 9 cities in Pearl River Delta, Guangdong province. A total of 183 cases of VLBW premature infants were enrolled in this research. The incidence of intrauterine growth retardation (IUGR) at birth and extrauterine growth retardation (EUGR) on discharge were assessed. According to IUGR at birth, they were assigned into two groups: IUGR group (n = 63) and non-IUGR group (n = 120). And non-IUGR group were further assigned into EUGR group (n = 71) and non-EUGR group (n = 49). The mean daily growth rate during hospitalization and the incidence of EUGR on discharge were studied comparatively to IUGR group and non-IUGR group. The nutrition intake, mean growth rate and relevant illnesses were studied comparatively to IUGR group and non-IUGR group, EUGR group and non-EUGR group.

RESULT: (1) The incidence of IUGR at birth was 34.4%, while the incidence of EUGR on discharge was 72.1%. The mean daily growth rate to body weight of IUGR group was higher than that of non-IUGR group [(12.5 ± 2.7) g/kg vs (11.3 ± 2.5) g/kg, P = 0.002]. The increasing incidence from IUGR to EUGR, IUGR group was higher than non-IUGR group (96.8% vs 59.2%, P = 0.000). (2) The mean daily energy and protein intake in postnatal time of 1 week [62 (51, 69) kcal/kg vs 56 (45, 64) kcal/kg (1 kcal = 4.1840 kJ), 1.7 (1.3, 2.0) g/kg vs 1.6 (1.2, 1.8) g/kg], 2 weeks [83 (71, 94) kcal/kg vs 76 (66, 88) kcal/kg, 2.6 (2.1, 2.9) g/kg vs 2.3 (1.9, 2.7) g/kg], 4 weeks [107 (94, 120) kcal/kg vs 95 (85, 108) kcal/kg, 3.3 (2.7, 3.6) g/kg vs 2.7 (2.4, 3.2) g/kg], before total enteral nutrition [103 (96, 110) kcal/kg vs 97 (89, 106) kcal/kg, 3.1 (2.6, 3.4) g/kg vs 2.8 (2.4, 3.3) g/kg] and the whole hospitalization [121 (111, 131) kcal/kg vs 111 (101, 119) kcal/kg, 3.4 (3.1, 3.8) g/kg vs 3.1 (2.8, 3.5) g/kg], IUGR group were more than non-IUGR group (P < 0.05).While the cumulative losses of energy [407 (360, 483) kcal/kg vs 448 (393, 527) kcal/kg, 534 (369, 689) kcal/kg vs 612 (453, 758) kcal/kg, 367 (12, 724) kcal/kg vs 718 (330, 996) kcal/kg, 381 (231, 609) kcal/kg vs 656 (394, 959) kcal/kg, 0 (0, 350) kcal/kg vs 387 (85, 826) kcal/kg] and protein [12.3 (10.2, 15.5) g/kg vs 13.7 (11.7, 16.4) g/kg, 12.8 (7.8, 19.4) g/kg vs 17.5 (11.9, 22.7) g/kg, 6.2 (0, 22.6) g/kg vs 21.7 (7.3, 30.3) g/kg, 6.6 (1.8, 23.0) g/kg vs 22.1 (7.2, 32.5) g/kg, 1.9 (0, 16.7) g/kg vs 20.1 (0, 32.6) g/kg] were lower in IUGR group than in non-IUGR group at the same time (P < 0.05). (3) The mean daily growth rate to body weight of non-EUGR group was higher than that of EUGR group [(12.7 ± 2.2) g/kg vs (10.3 ± 2.1) g/kg, P = 0.000]. The date beginning to feed [1.0 (1.0, 3.0) d vs 3.0 (2.0, 5.0) d], the total fasting time [3.0 (1.0, 5.5) d vs 4.0 (3.0, 9.0) d], the time to reach the lowest body weight [4.0 (3.0, 6.0) d vs 6.0 (5.0, 8.0) d], and the time to restoring birth weight [11.0 (9.0, 14.0) d vs 13.0 (10.0, 17.0) d], non-EUGR group were shorter than that of EUGR group (P < 0.05). The percentage of the infants who needed ventilator therapy was lower in non-EUGR group than in EUGR group (70.4% vs 51.0%, P = 0.031). (4) The mean daily energy intake in postnatal time of 2 weeks [81 (70, 91) kcal/kg vs 73 (63, 85) kcal/kg] and the mean protein intake daily in postnatal time of 1 week [1.6 (1.4, 2.0) g/kg vs 1.4 (1.1, 1.8) g/kg], 2 weeks [2.4 (2.1, 2.7) g/kg vs 2.1 (1.8, 2.6) g/kg] and before total enteral nutrition [3.0 (2.5, 3.4) g/kg vs 2.7 (2.3, 3.1) g/kg] were higher in non-EUGR group than in EUGR group (P < 0.05).While the cumulative losses of energy in postnatal time of 2 weeks [546 (403, 707) kcal/kg vs 655 (494, 795) kcal/kg] and the cumulative losses of protein in postnatal time of 1 week [13.1 (10.9, 15.1) g/kg vs 14.8 (12.0, 16.6) g/kg] and 2 weeks [15.5 (11.4, 19.8) g/kg vs 20.0 (12.1, 24.0) g/kg] were lower in non-EUGR group than in EUGR group (P < 0.05). (5) The incidence of neonatal respiratory distress syndrome was lower in IUGR group than in non-IUGR group (34.9% vs 56.7%, P = 0.005); the incidence of hypertensive disorders in pregnancy (54.0% vs 24.2%, P = 0.000) and fetal distress in uterus (25.4% vs 7.5%, P = 0.001)of the pregnant women were higher in IUGR group than in non-IUGR group. (6) The incidence of septicemia of the newborn (11.3% vs 0%, P = 0.020) and the incidence of hypertensive disorders in pregnancy of the pregnant women (31.0% vs 14.3%, P = 0.036) in EUGR group were higher than in non-EUGR group.

CONCLUSION: EUGR was still a serious problem in VLBWI. The risk of EUGR in the VLBWI with IUGR was much higher than those of non-IUGR. The relevant influencing factors of EUGR included mean daily growth rate to body weight, the date beginning to feed, the total fasting time, the time to reach the lowest body weight, the time to restoring birth weight, ventilator therapy, the daily nutrition intake, the cumulative nutrition losses, and illnesses of infants or their mother.