title: Prenatal detection of neural tube defects. VI. Experience with 20,000 pregnancies.
abstract: Neural tube defects (NTDs) are among the most common major congenital malformations in the United States. Prenatal detection is possible in about 95% of cases by assaying amniotic fluid for alpha-fetoprotein (AFP), which leaks from open lesions. In 20,000 pregnancies, 334 (1.7%) had a raised level of AFP. Of these, 136 (40.7%) had open NTDs, 90 (26.9%) had other fetal defects or conditions, and 108 (32.3%) almost invariably had admixed fetal blood. Pregnancy was electively terminated in 11 cases in which the AFP concentration was thought to be elevated but in which the fetus was apparently normal (0.06%), but in only two of these cases was there no explanation for the raised level of AFP. The practical false-positive rate was considerably below 0.06%. Patients at risk for bearing children with NTDs should be counseled and offered prenatal diagnosis.
mesh_terms: D000653:Amniotic Fluid / Q000032:analysis; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D005313:Fetal Death; D005865:Gestational Age; D006801:Humans; D009436:Neural Tube Defects / Q000175:diagnosis* / Q000235:genetics; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012306:Risk; D014463:Ultrasonography; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D000509:alpha-Fetoproteins