Statistical Study of Extremely Low Birth Weight (ELBW) Infants

Kim, Beyong Il; Choi, Jung Hwan; Yun, Chong Ku; Park, June Dong; Choi, Chang Won; Choi, Ji Won; Cho, Hee Seung; Kim, Hee Suk

Abstract

PURPOSE: The purpose of our study was to review the perinatal clinical characteristics of extremely low birth weight(ELBW) infants and determine their risk factors of their deaths.
METHODS
The medical records of 96 infants weighing less than 1,000g, who were born at Seoul National University Hospital and admitted to our neonatal intensive care unit(NICU) were analyzed retrospectively on the basis of clinical characteristics, obstetrical problems, postnatal complications and outcome.
RESULTS
The annual birth rate of ELBW infants was 0.11% to 0.90% of total live births and the mean annual birth rate was 0.56% at Seoul National University Hospital. Preeclampsia was the most common obstetrical problem(34.4%), followed by incompetent internal os of cervix(IIOC) (13.5%), multiple pregnancy(13.5%) and in vitro fertilization(IVF)(13.5%). Respiratory distress syndrome(RDS) was the most common postnatal complication(78.1%), followed by sepsis(60.4%) and apnea(39.6%). Comparing the ELBW infants weighing less than 750g with those weighing more than 751g, sepsis was more frequent in the latter group(p<0.05), whereas high grade intraventricular hemorrhage(grade Ill) was more frequent in the former group(p<0.05). Otherwise there was no statistically significant difference concerning the frequency of perinatal complications between two groups. Comparing the ELBW infants born before the year 1991, when surfactant treatment started to be used routinely at our NICU, with those born after the year 1991, apnea and sepsis could be observed more frequent in the latter group(p<0.05). Otherwise there was no statistically significant difference in the frequency of perinatal complications between two groups, The survival rate of ELBW infants was 0.0% in 1986, 50.0% in 1991 and 40.0% in 1995. The risk factors of neonatal deaths of ELBW infants included birth weight, gestational period, mode of delivery, IIOC, RDS, apnea, pneumonia, pneumothorax, acute renal failure(ARF) and infections(except pneumonia), but analyzing these risk factors by multivariate logistic regression analysis, the resultant significant independent risk factors consisted only of birth weight, RDS and pneumonia(p<0.05). There was no statistically significant difference in survival rate between ELBW infants born before and after the year 1991, but there was a tendency toward increasing survival rates in the latter group.
CONCLUSION
Recently, the survival rate of ELBW infants is improving steadily, but is still lower than that of western countries and postnatal morbidity remains high. Therefore, there is an urgent need to give more efforts to the neonatal intensive care of ELBW inFants in order to increase survival rates and reduce postnatal morbidity. But it is more important to reduce preterm birth by the treatment of preventable obstetrical risk factors.