[Extrauterine growth retardation and correlated factors in premature neonates]

Poor growth is a common problem in premature neonates. No sufficient attention has been paid to the nutrition deficit and extrauterine growth retardation in premature neonates in China. The present study aimed to assess the incidences of intrauterine growth retardation (IUGR) and extrauterine growth retardation (EUGR) in premature neonates in Shanghai area and their correlated factors.

Data of the neonates discharged between January 1, 2003 and December 31, 2004 from 5 hospitals (Xinhua Hospital, Shanghai Children's Medical Center, Shanghai Children's Hospital, Pediatric Hospital Affiliated to Fudan University, and Shanghai International Peace Maternity and Child Health Hospital) were reviewed. The criteria of exclusion were cases who died or had a malformed appearance, the mother had endocrine or metabolic diseases. The criteria for enrollment were (1) gestational age < 37 weeks, (2) admitted less than 24 hours after birth and discharged from the same hospital, (3) duration of hospitalization was > or = 7 days. The growth values on discharge of each patient were compared to the expected values based on the intrauterine growth data and postmenstrual day on discharge. Growth retardation was defined as measured growth values (weight, head circumference) < or = 10th percentile of the values (growth expectation based on estimated postmenstrual age). In each specific group, the number of neonates with < or = 10(th) percentile for each growth parameter was counted and the percentages of patients who had values < or = 10(th) percentile on birth and discharge were calculated. The growth curves used for assessing birth weight and head circumference for different gestational age neonates were those published in 1986. All the data were analyzed using the SPSS statistical software package. The risk factors for extrauterine growth retardation on weight and head circumference were estimated with logistic regression model.

The subjects included 1196 premature neonates in the five hospitals (734 boys and 462 girls). The incidence of IUGR was 22.7% and 19.2% assessed by weight and head circumference, respectively. The incidence of EUGR was 49.7% and 23.1% assessed by weight and head circumference, respectively. Assessment of IUGR in accordance with the birth weight and head circumference in the five hospitals showed no significant correlation between IUGR and non-IUGR by birth weight (chi(2) = 4.944) and head circumference (chi(2) = 0.017) respectively. Whereas the assessment of EUGR in accordance with weight and head circumference showed a significant correlation between EUGR and non-EUGR by weight on discharge (chi(2) = 28.109), but no significant correlation was found between EUGR and non-EUGR by head circumference on discharge (chi(2) = 0.275). In specific birth weight groups, the lower the weight, the higher the incidence of IUGR and EUGR by the weight and head circumference. The incidence of EUGR in VLBWI was 78.9% and 50.0% assessed by weight and head circumference, respectively. Assessed by weight, significant correlation was observed between EUGR and non-EUGR in birth weight (t = 18.674), hospitalization duration (Z = -8.790) and the median number of day for total using EN (Z = -4.650); but by the head circumference, significant correlation was observed in head circumference at birth (t = 9.555), hospitalization duration (Z = -3.930) and the median number of day for total using EN (Z = -3.004). The relationship between EUGR and some risk factors was analyzed with Logistic regression model. Assessed by the weight, the following 4 factors were related to EUGR: sex (chi(2) = 10.351), gestation age at birth (chi(2) = 56.275), birth weight (chi(2) = 102.126) and different hospital (chi(2) = 4.773). Assessed by the head circumference, the following 2 factors were correlated: gestation age at birth (chi(2) = 10.322) and head circumference (chi(2) = 10.620).

This study showed that the incidence of EUGR in premature neonates was significantly higher than the data reported in other countries. The incidence of EUGR increased with the decreased birth weight. Different nutritional support had influence on EUGR.