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Nearly 80% of birth defects have unknown etiology
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The cause of birth defects could only be identified in one in five infants, with the burden of these defects — which include fetal loss — underestimated by at least 25%, according to research published in The BMJ.
“The occurrence of birth defects, with few localized exceptions (such as neural tube defects in countries that implemented folic acid fortification), has not decreased for many decades. Birth defects might indeed increase worldwide, with the alarming increase of known risk factors, such as maternal diabetes and obesity,” Marcia L. Feldkamp, PA, MSPH, PhD, from the Division of Medical Genetics and the Department of Pediatrics at the University of Utah School of Medicine, and colleagues wrote.
“Unless progress is made in identifying and preventing the root causes of birth defects, these conditions will continue to have draining effects on the survival and health of individuals, families and countries,” the researchers added.
To determine the cause and presentation of several major birth defects, including talipes equinovarus, congenital hip dysplasia or dislocation and cryptorchidism, the researchers conducted a population-based case cohort study in which data concerning infants born between 2005 and 2009 with birth defects were gathered. All data were collected through a population-based surveillance system in Utah.
Of the 270,878 infants born within this time, 5,504 were born with a birth defect. Mild isolated conditions were excluded from the study. From these infants, researchers attempted to determine the proportion of infants who did not have a determinable cause of their defect, as well as morphology and pathogenesis.
Only 20.2% (n=1,114) of the infants included had a definitive source of their birth defect. Most (94.4%; n=1,052) of these conditions were instigated by chromosomal or genetic conditions, while 4.1% (n=46) were triggered by teratogens, such as poorly controlled maternal diabetes. Additionally, 1.4% (n=16) were caused by twinning.
The remaining infants included in the study had no definitive source of their various defects (79.8%; n=4,390). Isolated birth defects were observed within 88.2% (n=3,874) of these infants, and first-degree relatives who had similar birth defects were noted in 4.8% of cases. Overall, most were live births (92.1%), and overall isolated birth defects of known or unknown etiology were observed within 75.3% of patients.
“Understanding the etiology of birth defects should be both a public health and research priority,” Feldkamp and colleagues wrote. “Our findings underscore the large gaps in current knowledge of the causes of birth defects. These gaps in turn represent opportunities for both basic and translational researchers.” — by Katherine Bortz
Disclosure: The researchers reported no relevant financial disclosures.
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