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Birth weight-specific causes of infant mortality, United States, 1980
Insights
Infants with lower birth weights (500-2,499g) face higher risks of death from most causes. Perinatal conditions dominate neonatal deaths, while SIDS, congenital anomalies, infections, and injuries are key postneonatal causes, with significant racial disparities observed.
Area of Science:
- Neonatal and Perinatal Medicine
- Pediatric Epidemiology
- Public Health
Background:
- Infant mortality remains a critical public health concern, with birth weight being a significant determinant of survival.
- Understanding the specific causes of death across different birth weight strata is essential for targeted interventions.
- Previous national data on birth weight-specific infant mortality was limited, necessitating updated analysis.
Purpose of the Study:
- To delineate the underlying causes of infant mortality stratified by birth weight.
- To compare mortality causes between neonatal and postneonatal periods.
- To identify trends and disparities in infant death causes from 1960 to 1980.
Main Methods:
- Utilized data from the 1980 National Infant Mortality Surveillance project.
- Aggregated International Classification of Diseases codes into seven cause-of-death categories.
- Analyzed mortality data across multiple birth weight groups (500-2,499g and heavier).
Main Results:
- Infants weighing 500-2,499g had increased risk of neonatal and postneonatal death from most causes compared to heavier infants.
- Perinatal conditions, including prematurity-low birth weight and respiratory distress syndrome (RDS), were leading causes of neonatal death, particularly in lower birth weight infants.
- Congenital anomalies were the second leading cause of neonatal death. Predominant postneonatal causes included sudden infant death syndrome (SIDS), congenital anomalies, infections, and injuries.
- Black infants exhibited a twofold higher risk of death than white infants, except for congenital anomalies. SIDS emerged as a major cause of death between 1960 and 1980.
Conclusions:
- Birth weight is a critical factor influencing infant mortality risk and cause-specific death rates.
- Perinatal conditions are primary drivers of early neonatal mortality, while SIDS, congenital anomalies, infections, and injuries are significant in later infancy.
- Significant racial disparities persist in infant mortality, underscoring the need for equitable healthcare access and targeted public health strategies.
Abstract:
To describe underlying causes of infant death by birth weight, we used data from the 1980 National Infant Mortality Surveillance project and aggregated International Classification of Diseases codes into seven categories: perinatal conditions, infections, congenital anomalies, injuries, sudden infant death syndrome (SIDS), other known causes, and nonspecific or unknown causes. Compared with heavier infants, infants with birth weights of 500-2,499 grams (g) are at increased risk of both neonatal and postneonatal death for virtually all causes. Sixty-two percent of neonatal deaths (under 28 days of life) were attributed to "conditions arising in the perinatal period," as defined using codes from the International Classification of Diseases. Prematurity-low birth weight and respiratory distress syndrome (RDS) were the leading causes of such deaths among infants with birth weights of 500-2,499 g, while birth trauma-hypoxia-asphyxia and other perinatal respiratory conditions were the leading causes among heavier infants. For all birth weight groups, congenital anomalies were the second leading cause, representing 27 percent of neonatal deaths. Although perinatal conditions caused nearly one-third of postneonatal deaths (28 days to under 1 year of life) among infants with birth weights of 500-1,499 g, for the other birth weight groups these conditions were much less important; predominant causes of postneonatal death were sudden infant death syndrome (SIDS), congenital anomalies, infections, and injuries. Black infants had a roughly twofold higher risk of neonatal and postneonatal death than did white infants for all causes except congenital anomalies, which occurred with almost equal frequency in blacks and whites. However, for infants with birth weights of 500-2,499 g, blacks had lower risks of neonatal death from RDS and congenital anomalies. Between 1960 (the latest year for which national birth weight-specific mortality statistics had been available) and 1980, SIDS emerged as a major diagnostic rubric. Otherwise, except for infections and congenital anomalies among infants with birth weights of 500-1,499 g, all causes of death declined in frequency among all birth weight groups.