title: Two consecutive singleton pregnancies versus one twins pregnancy as preferred outcome of in vitro fertilization for mothers and infants: a retrospective case-control study.
abstract: OBJECTIVE
  Many infertile couples request a multiple embryo transfer because they desire more than one child. Based on this consideration, the current study aimed to compare the reproductive and perinatal outcomes of two consecutive singleton pregnancies versus one twin pregnancy in a large cohort of in vitro fertilization (IVF) patients.
  
  
  METHODS
  Retrospective analysis of data from patients with clinical twin pregnancy after IVF fresh cycles and from patients with two consecutive IVF fresh cycles and clinical singleton pregnancy.
  
  
  METHODS
  Miscarriage rate, delivery rate, gestational age at birth, neonatal birth weight, and perinatal complications. A sub-analysis of data according to vanishing twin syndrome (VTS) was also performed.
  
  
  RESULTS
  A total of 18,703 autologous fresh cycles were analyzed. One hundred seven patients had two consecutive singleton clinical pregnancies, whereas one clinical twin pregnancy occurred in 641 women. In patients who had two consecutive singleton clinical pregnancies the rates of overall pregnancies lost (odds ratio [OR] 4.9, 95% confidence interval [CI] 3.4, 6.9) and live births (OR 0.2, 95% CI 0.1, 0.3) were, respectively, higher and lower when compared to patients who had one clinical twin pregnancy. That data did not change after sub-analysis for VTS. The overall risk of perinatal complications was significantly higher in patients who had one twin delivery rather than patients who had two consecutive singleton deliveries (OR 31.8, 95% CI 14.1, 71.5). No difference between groups was detected in terms of intrauterine/neonatal deaths, perinatal mortality and neonatal intensive care unit admission. Data did not change after adjusting for confounders.
  
  
  CONCLUSIONS
  When compared with two consecutive singleton pregnancies, twin pregnancies are characterized by higher success rates but worse perinatal outcomes irrespectively of VTS. Well designed prospective controlled studies are needed to confirm or rebut current retrospective findings.
authors.affiliation: a Center of Reproductive Medicine and Surgery, Arcispedale Santa Maria Nuova (ASMN) - Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) , Reggio Emilia , Italy ;|b University of Modena and Reggio Emilia , Italy ;
authors.forename: Giovanni Battista
authors.initials: GB
authors.lastname: La Sala
authors.affiliation: a Center of Reproductive Medicine and Surgery, Arcispedale Santa Maria Nuova (ASMN) - Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) , Reggio Emilia , Italy ;
authors.forename: Daria
authors.initials: D
authors.lastname: Morini
authors.affiliation: c Department of Woman and Child Health , University of Padua , Padua , Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Gizzo
authors.affiliation: a Center of Reproductive Medicine and Surgery, Arcispedale Santa Maria Nuova (ASMN) - Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) , Reggio Emilia , Italy ;
authors.forename: Alessia
authors.initials: A
authors.lastname: Nicoli
authors.affiliation: a Center of Reproductive Medicine and Surgery, Arcispedale Santa Maria Nuova (ASMN) - Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) , Reggio Emilia , Italy ;
authors.forename: Stefano
authors.initials: S
authors.lastname: Palomba
mesh_terms: D000022:Abortion, Spontaneous; D000328:Adult; D001723:Birth Rate; D016022:Case-Control Studies; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D005865:Gestational Age; D006801:Humans; D007247:Infertility, Female / Q000628:therapy*; D050498:Live Birth; D008423:Maternal Age; D009035:Mothers; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D011446:Prospective Studies; D018456:Reproductive Medicine / Q000379:methods; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D014427:Twins
keywords: ART; Complications; IVF; Perinatal outcome; Pregnancy loss; Vanishing twin syndrome