title: Impact of chorionicity on risk and timing of intrauterine fetal demise in twin pregnancies.
abstract: OBJECTIVE
  We sought to estimate the association between chorionicity and intrauterine fetal demise (IUFD) of one or both fetuses in twin pregnancies.
  
  
  METHODS
  In a retrospective cohort of twins undergoing anatomic survey, risk of IUFD in monochorionic and dichorionic twins was compared. The primary outcome was IUFD of one or both fetuses; secondary outcomes included nonanomalous fetal deaths.
  
  
  RESULTS
  Of 2161 twin pregnancies meeting inclusion criteria, 86 had at least 1 IUFD and 32 experienced a double fetal loss. Monochorionic pregnancies had an increased risk of a single demise (adjusted odds ratio, 1.69; 95% confidence interval, 1.04-2.75) and a double demise (adjusted odds ratio, 2.11; 95% confidence interval, 1.02-4.37). Of all double demises, 70% occurred <24 weeks.
  
  
  CONCLUSIONS
  Monochorionic twins carry an increased risk of fetal death compared to dichorionic twins. Double demise occurs primarily <24 weeks, regardless of chorionicity.
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA. mcphersonj@wudosis.wustl.edu
authors.forename: Jessica A
authors.initials: JA
authors.lastname: McPherson
authors.forename: Anthony O
authors.initials: AO
authors.lastname: Odibo
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Shanks
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Roehl
authors.forename: George A
authors.initials: GA
authors.lastname: Macones
authors.forename: Alison G
authors.initials: AG
authors.lastname: Cahill
mesh_terms: D000328:Adult; D002823:Chorion; D005260:Female; D006801:Humans; D011247:Pregnancy; D059285:Pregnancy, Twin; D012189:Retrospective Studies; D012307:Risk Factors; D050497:Stillbirth; D013997:Time Factors; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic