title: Neonatal outcomes of preterm twins according to mode of birth and presentation.
abstract: OBJECTIVE
  To compare neonatal outcomes of twins delivered <33 weeks' gestation in tertiary centers in Canada according to the mode of birth and presentation.
  
  
  METHODS
  This retrospective cohort from the Canadian Neonatal Network database studied preterm twins born from 24 + 0 to 32 + 6 weeks' gestation between 2005 and 2012. Twins were grouped by the mode of birth: both vaginal, combined vaginal/cesarean section (CS), and both CS. Additionally, twins were grouped by the mode of presentation: both vertex, vertex/breech, breech/vertex, and both breech. The primary outcome was a composite of mortality or severe neonatal morbidity (severe neurological injury [intraventricular hemorrhage grade 3/4 or periventricular leukomalacia], bronchopulmonary dysplasia, retinopathy of prematurity, and necrotizing enterocolitis).
  
  
  RESULTS
  Of the 6636 twins, 1934 (29%) were delivered vaginally, 418 (6%) by combined vaginal birth/CS, and 4284 (65%) were born by CS. The composite did not differ between the groups. However, severe neurological injury was decreased (adjusted odds ratio [AOR], 0.77; 95% confidence interval [CI], 0.61-0.98) and respiratory distress syndrome (AOR, 1.34; 95%CI, 1.15-1.56) was increased when both the twins were delivered by CS.
  
  
  CONCLUSIONS
  Preterm twin infants born via CS experienced less severe neurological injury when compared to those delivered vaginally, but had an increase in respiratory distress syndrome.
authors.affiliation: a Department of Obstetrics & Gynaecology , University of Toronto , Toronto , Canada.|b Department of Obstetrics & Gynaecology , Mount Sinai Hospital , Toronto , Canada.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Hunter
authors.affiliation: c Department of Paediatrics , Mount Sinai Hospital , Toronto , Canada.
authors.forename: Jyotsna
authors.initials: J
authors.lastname: Shah
authors.affiliation: d Department of Pediatrics , University of British Columbia , Vancouver , Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Synnes
authors.affiliation: e Department Pediatrics , McMaster University , Hamilton , Canada.
authors.forename: Sandesh
authors.initials: S
authors.lastname: Shivananda
authors.affiliation: a Department of Obstetrics & Gynaecology , University of Toronto , Toronto , Canada.|b Department of Obstetrics & Gynaecology , Mount Sinai Hospital , Toronto , Canada.
authors.forename: Greg
authors.initials: G
authors.lastname: Ryan
authors.affiliation: c Department of Paediatrics , Mount Sinai Hospital , Toronto , Canada.
authors.forename: Prakesh S
authors.initials: PS
authors.lastname: Shah
authors.affiliation: a Department of Obstetrics & Gynaecology , University of Toronto , Toronto , Canada.|b Department of Obstetrics & Gynaecology , Mount Sinai Hospital , Toronto , Canada.
authors.forename: Kellie E
authors.initials: KE
authors.lastname: Murphy
mesh_terms: D000328:Adult; D002170:Canada / Q000453:epidemiology; D036861:Delivery, Obstetric / Q000009:adverse effects* / Q000379:methods; D004200:Diseases in Twins / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000453:epidemiology / Q000209:etiology*; D007746:Labor Presentation; D016015:Logistic Models; D008297:Male; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Infant; mode of delivery; mortality; multiple pregnancy; neurological injury; premature; respiratory distress syndrome