Role of structural birth defects in preterm delivery.
The proportion of preterm births associated with structural birth defects has not been adequately quantified. We explored the proportion of preterm infants with structural birth defects diagnosed in the first year of life, as well as the specific phenotypes of birth defects occurring among preterm infants. The data used were from the California Birth Defects Monitoring Program, a population-based registry, as well as data from California vital records corresponding to births and fetal deaths in the period 1984-96. The prevalence of structural birth defects exceeded 8% among deliveries with gestational ages < or = 30 weeks, and prevalence decreased to 2% as gestational age increased to > or = 37 weeks gestation. The decreasing prevalence pattern with increasing gestational age was observed for a variety of anatomically defined birth defect groups suggesting that certain birth defects were not the sole contributors to the elevated prevalences among preterm births. Decreasing prevalence with increasing gestational age was also observed across strata of maternal race/ethnicities, ages, infant's sex and each year studied. These data indicate that structural birth defects may contribute significantly to the proportion of infants who are delivered before 37 weeks gestation.
Shaw
G M
GM
March of Dimes Birth Defects Foundation, California Birth Defects Monitoring Program, Oakland 94606, USA. gsh@cbdmp.org
Savitz
D A
DA
Nelson
V
V
Thorp
J M
JM
D000013:Congenital Abnormalities / Q000473:pathology*; D016021:Epidemiologic Studies; D005006:Ethnicity; D005260:Female; D005313:Fetal Death; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D007752:Obstetric Labor, Premature / Q000209:etiology*; D010641:Phenotype; D011247:Pregnancy; D015995:Prevalence; D044469:Racial Groups; D012042:Registries; D012307:Risk Factors