title: Outcome of monochorionic twins conceived by assisted reproduction.
abstract: OBJECTIVE
  To evaluate monochorionic twins conceived by assisted reproductive technology (ART).
  
  
  METHODS
  We compared perinatal outcomes of monochorionic twins conceived by ART with their dichorionic counterparts and with spontaneous monochorionic twins.
  
  
  METHODS
  Referral center.
  
  
  METHODS
  Mothers to monochorionic and dichorionic twins conceived by ART and spontaneous monochorionic twins.
  
  
  METHODS
  None.
  
  
  METHODS
  Maternal characteristics, pregnancy complications, and perinatal outcomes.
  
  
  RESULTS
  Monochorionic twin pregnancies (n = 25) comprise 7.2% of all ART twins and 4.9% of all monochorionic twins in this data set. Monochorionic pairs have a significantly worse outcome compared with dichorionic sets in terms of lower gestational age and birth weight. ART appears to increase the already high risk of monochorionicity compared with spontaneous conception: odds ratio (OR), 2.9 (1.1-7.3) for preterm birth at <32 weeks and OR, 5.9 (2.5-1.49) for birth weight <1,500 g.
  
  
  CONCLUSIONS
  Monochorionic twins after ART are at increased risk of adverse perinatal outcomes compared with spontaneous monochorionic twins and with dichorionic twins conceived by ART.
authors.affiliation: Department of Maternal-Fetal Medicine Maternity Hospital, Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central and Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: Teresinha
authors.initials: T
authors.lastname: Simões
authors.affiliation: Department of Maternal-Fetal Medicine Maternity Hospital, Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central and Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Queirós
authors.affiliation: Department of Maternal-Fetal Medicine Maternity Hospital, Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central and Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: Ana Teresa
authors.initials: AT
authors.lastname: Marujo
authors.affiliation: Department of Maternal-Fetal Medicine Maternity Hospital, Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central and Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: Sandra
authors.initials: S
authors.lastname: Valdoleiros
authors.affiliation: Department of Maternal-Fetal Medicine Maternity Hospital, Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central and Universidade Nova de Lisboa, Lisbon, Portugal.
authors.forename: Patricia
authors.initials: P
authors.lastname: Silva
authors.affiliation: Obstetrics and Gynecology, Kaplan Medical Center, Rehovot, and the Hadassah-Hebrew University School of Medicine, Jerusalem, Israel. Electronic address: blick@netvision.net.il.
authors.forename: Isaac
authors.initials: I
authors.lastname: Blickstein
mesh_terms: D000328:Adult; D001724:Birth Weight; D016009:Chi-Square Distribution; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D019102:Infant, Very Low Birth Weight; D016017:Odds Ratio; D011247:Pregnancy; D011248:Pregnancy Complications / Q000209:etiology* / Q000503:physiopathology; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000209:etiology / Q000503:physiopathology; D027724:Reproductive Techniques, Assisted / Q000009:adverse effects*; D012307:Risk Factors; D016896:Treatment Outcome; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D055815:Young Adult
keywords: Monochorionic twins; assisted reproduction; pregnancy complications