title: Outcome of twin gestations complicated by a single anomalous fetus.
abstract: OBJECTIVE
  To compare the outcome of twin gestations complicated by a single anomalous fetus with twin gestations with no fetal anomalies.
  
  
  METHODS
  The study included all patients with twin gestations diagnosed with a fetal anomaly in one fetus during 1990-1994, and excluded twin gestations with anomalies in both fetuses. The control twin group was composed of all other normal twin pregnancies followed and delivered at our center in the preceding 2 years.
  
  
  RESULTS
  We reviewed 24 twin gestations with at least one anomalous fetus. Five cases were excluded because of anomalies in both fetuses, and a further five pregnancies had selective termination or termination of the entire pregnancy. There were 14 ongoing twin pregnancies with one anomalous fetus, and their median gestational age at diagnosis was 18 weeks (range 16-20). All twin anomalies were correctly diagnosed antenatally. Gestational age at delivery and birth weight were significantly lower for twins complicated by an anomaly compared with control twins (P = .008 and P = .001, respectively). The cesarean delivery and perinatal mortality rates of twin pregnancies with anomalies were significantly higher than those of normal twins (P = .01 and P < .001, respectively).
  
  
  CONCLUSIONS
  The presence of a single anomalous fetus in a twin gestation significantly increases the risk of preterm delivery compared with nonanomalous twin gestations.
authors.affiliation: Department of Obstetrics and Gynecology, Tufts University School of Medicine, New England Medical Center, Boston, Massachusetts, USA.
authors.forename: F D
authors.initials: FD
authors.lastname: Malone
authors.forename: S D
authors.initials: SD
authors.lastname: Craigo
authors.forename: D
authors.initials: D
authors.lastname: Chelmow
authors.forename: M E
authors.initials: ME
authors.lastname: D'Alton
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004200:Diseases in Twins / Q000453:epidemiology; D005260:Female; D005315:Fetal Diseases / Q000453:epidemiology; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D012307:Risk Factors; D014427:Twins