Year : 2017 | Volume
: 5 | Issue : 1 | Page : 1--2
Birth weight versus gestational age as a predictor of viability of extremely low birth weight babies
King Abdullah International Medical Research Center, King Saud bin-Abdulaziz University for Health Sciences, Ministry of National Guard - Health Affairs, Riyadh, Saudi Arabia
King Abdullah International Medical Research Center, King Saud bin-Abdulaziz University for Health Sciences, Ministry of National Guard - Health Affairs, Riyadh
|How to cite this article:|
Abolfotouh M. Birth weight versus gestational age as a predictor of viability of extremely low birth weight babies.Saudi J Obesity 2017;5:1-2
|How to cite this URL:|
Abolfotouh M. Birth weight versus gestational age as a predictor of viability of extremely low birth weight babies. Saudi J Obesity [serial online] 2017 [cited 2018 May 25 ];5:1-2
Available from: http://www.saudijobesity.com/text.asp?2017/5/1/1/210587
Survival of preterm neonates has steadily improved over the past five decades. The gestational age at which at least half of the infants survive has decreased from 30 to 31 weeks in the 1960s to 23–24 weeks during this decade. This change might be attributed to the changes in the neonatal intensive care in the past decade, such as the use of antenatal corticosteroids for women at risk for preterm delivery, surfactant for the prevention and treatment of neonatal respiratory distress syndrome, postnatal steroids for chronic lung disease, and new modes of respiratory support for neonates with respiratory distress.
Although neurodevelopmental outcome of very preterm neonates has also significantly improved over this period, the pace of improvement in central nervous system morbidity appears to have lagged behind that of survival. In addition, neurodevelopmental impairment in infants born extremely immature persists into school age, and the level of impairment is often underestimated when standardized tests are being used for the assessment of these patients’ cognitive and neurological status. Among extremely preterm children, cognitive and neurologic impairment is common at school age. A comparison with their classroom peers indicates a level of impairment that is greater than is recognized with the use of standardized norms. The extremely low birth weight (ELBW) survivors in school at age 8 years who were born in the 1990s have considerable long-term health and educational needs. A meta-analysis of case–control studies reported from 1980 to November 2001 that examined cognitive and behavioral outcomes found that the mean intelligent quotient (IQ) for school-aged children born very preterm was approximately two-thirds standard deviation (SD) below that of healthy controls.
Data on survival and long-term neurodevelopmental outcome in very preterm infants are influenced by multiple factors and need to be carefully assessed. Adding to the complexity of this issue is the finding that very preterm neonates have a survival advantage if they are born at large perinatal–neonatal centers where caregivers have significant experience in providing perinatal and neonatal care and a comprehensive multidisciplinary operational structure is in place.
The World Health Organization places 22 weeks of gestational age or 500 g birth weight as the lower limit of viability. The International Classification of Diseases describes the perinatal period as starting at 22 completed weeks (154 days) gestation and ending seven complete days after birth. The Eugenic Protection Act in Japan was amended in 1991, shortening the viability limit from 24 to 22 completed weeks of gestation. The American Academy of Pediatrics suggests that non-initiation of resuscitation for newborns of less than 23 weeks gestational age and/or 400 g in birth weight is appropriate. These amendments directly encourage physicians to fully resuscitate these infants at the delivery room without considering the high mortality and morbidity.
A study was conducted at King Abdulaziz Medical city, Ministry of National Guard − Health Affairs, Riyadh, Saudi Arabia, to determine the lower limit of viability and survival (RC09/079). It showed that, after applying the receiver operating characteristic curve to identify the optimum cutoff for birth weight and gestational age for viability of ELBW, the optimum gestational age (GA) for viability is 25 weeks. At this GA, the sensitivity and specificity are 66.2 and 58.5%, respectively. Meanwhile, the optimum birth weight for viability is 700 g. At this cutoff, the sensitivity and specificity are 80 and 58.5%. Having the same specificity for both GA and birth weight (BW), and based on the level of sensitivity, birth weight would be considered as more valid for prediction of viability of ELBW infants, as the sensitivity is 80% as compared to only 66.2% for GA. The APPs for process of care of ELBW need to be revisited so as to take into consideration the findings of this study.
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