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Prevalence of birth defects among low-birth-weight infants. A population study
F Mili1, L D Edmonds, M J Khoury
1Division of Birth Defects and Developmental Disabilities, Centers for Disease Control, Atlanta, GA 30333.
Insights
Major birth defects significantly increase with lower infant birth weights, with rates highest in newborns under 1500g. This highlights the critical link between birth defects and low birth weight, impacting infant health outcomes.
Area of Science:
- Pediatrics
- Public Health
- Genetics
Background:
- Major birth defects affect 3%-4% of infants annually.
- Birth defect rates are known to vary with infant birth weight, particularly in cases of intrauterine growth retardation or prematurity.
- Previous studies have not adequately quantified this variation in well-defined populations.
Purpose of the Study:
- To investigate the relationship between infant birth weight and the rate of major birth defects.
- To quantify the magnitude of variation in birth defect rates across different birth weight categories.
- To understand the contribution of birth defects to morbidity in low birth weight infants.
Main Methods:
- Analysis of population-based data from the Metropolitan Atlanta Congenital Defects Program (1978-1988).
- Inclusion of 11,398 infants diagnosed with serious birth defects among 317,499 singleton live-born infants.
- Statistical analysis of birth defect rates across defined birth weight strata.
Main Results:
- An overall birth defect rate of 3.6% was observed.
- A significant inverse relationship exists between birth defect rates and infant birth weight.
- Birth defect rates ranged from 16.2% (infants <1500g) to 2.8% (infants ≥4000g), with most defects associated with low birth weight.
Conclusions:
- Low birth weight is strongly associated with a higher risk of major birth defects.
- Birth defects contribute significantly to the excess morbidity observed in low birth weight infants.
- Preventing low birth weight requires better understanding of its complex etiology and risk factors for birth defects.
Abstract:
Major birth defects are diagnosed in about 3% to 4% of infants during their first year of life. Because many infants with birth defects have intrauterine growth retardation, are born prematurely, or both, the rate of birth defects undoubtedly varies according to the infant's birth weight. Nevertheless, the magnitude of such variation has not, to our knowledge, been adequately studied in well-defined populations. We analyzed data from the population-based Metropolitan Atlanta (Ga) Congenital Defects Program for 1978 through 1988. These data included information on 11,398 infants who were diagnosed with serious birth defects among 317,499 singleton live-born infants. Although the overall rate of birth defects was 3.6%, we observed a striking inverse relationship between the birth defects rate and the infants' birth weights. The birth defect rates were 16.2% for newborns weighing less than 1500 g at birth, 13.2% for newborns weighing from 1500 g to 1999 g, 6.2% for newborns weighing from 2000 g to 2499 g, 3.2% for newborns weighing from 2500 g to 3999 g, and 2.8% for newborns weighing 4000 g or more. Analyses by type of defect indicated that most birth defects were significantly associated with low birth weight. The higher risk of birth defects among low-birth-weight infants demonstrates that birth defects contribute to excess morbidity among low-birth-weight infants. Because of the overlap between birth defects and low birth weight, the prevention of low birth weight in the population depends greatly on a better recognition of the complex etiology of low birth weight and, in part, on the delineation of risk factors that influence the occurrence of birth defects.