title: Effects of placental chorionicity on outcome in twin pregnancies. A cohort study.
abstract: OBJECTIVE
  To examine the effects of the chorionicity of the placenta on infant outcome at 1 year of age in twin pregnancies.
  
  
  METHODS
  Cohort study and retrospective review of the medical records of 44 monochorionic (MC) and 164 dichorionic (DC) twin gestations that had been followed at our institution since < 20 weeks' gestation. Physical and neurologic status was assessed at 1 year of corrected age in infants born to these 208 women.
  
  
  RESULTS
  Adverse infant outcomes, such as death, cerebral palsy and mental retardation, occurred in 9 (10%) of 88 MC infants (4 deaths and 5 disabled infants) as compared with 12 (3.7%) of 328 DC infants (6 deaths and 6 disabled infants) (P < .05). Although delivery occurred one week earlier in MC than in DC twins (34.7 +/- 2.8 vs. 35.7 +/- 2.3 weeks, P < .01), there was no significant difference in gestational age at birth or birth weight between the 9 MC and 12 DC infants with adverse outcomes. A presumptive antenatal diagnosis of twin-twin transfusion syndrome (TTTS) was made in 14 (32%) of the 44 MC twin gestations. TTTS was considered to be responsible for adverse outcome in 7 MC infants. All 9 MC infants with adverse outcomes and 4 (33%) of 12 DC infants with adverse outcomes belonged to pairs that had weight discordance > or = 25% (P < .01).
  
  
  CONCLUSIONS
  MC twins had an increased risk of adverse outcomes as compared with DC twins, mainly because of TTTS. In both MC and DC twins, a birth weight discordance > or = 25% was associated with adverse infant outcomes. The number of infants with disabilities at 1 year of age was equal to the number of deaths.
authors.affiliation: Department of Obstetrics and Gynecology, Jichi Medical School, Tochigi, Japan. minasho@jichi.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Minakami
authors.forename: Y
authors.initials: Y
authors.lastname: Honma
authors.forename: S
authors.initials: S
authors.lastname: Matsubara
authors.forename: A
authors.initials: A
authors.lastname: Uchida
authors.forename: H
authors.initials: H
authors.lastname: Shiraishi
authors.forename: I
authors.initials: I
authors.lastname: Sato
mesh_terms: D000328:Adult; D001724:Birth Weight; D002823:Chorion / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D004200:Diseases in Twins; D005260:Female; D005330:Fetofetal Transfusion / Q000000981:diagnostic imaging / Q000209:etiology*; D006801:Humans; D007223:Infant; D008499:Medical Records; D010920:Placenta / Q000002:abnormalities / Q000000981:diagnostic imaging; D011247:Pregnancy; D011256:Pregnancy Outcome; D011272:Pregnancy, Multiple; D012189:Retrospective Studies; D012307:Risk Factors; D014427:Twins; D016216:Ultrasonography, Prenatal