title: Twin births: cesarean section or vaginal delivery?
abstract: OBJECTIVE
  To assess morbidity and mortality in twin pregnancy deliveries, according to chorionicity and mode of delivery.
  
  
  METHODS
  Population-based retrospective cohort.
  
  
  METHODS
  Fourteen obstetric departments in Denmark.
  
  
  METHODS
  One thousand one hundred and seventy-five twin pregnancies with two live fetuses at 36(+0) weeks of gestation.
  
  
  METHODS
  Pregnancy outcomes assessed according to chorionicity and mode of delivery.
  
  
  METHODS
  Poor outcome defined as five min Apgar score ≤ 7, umbilical artery pH < 7.10, admission to neonatal unit for more than three days or death.
  
  
  RESULTS
  Dichorionic (DC) twins, delivered after 36 gestational weeks, with intended vaginal delivery (n= 689) compared with DC twins with planned cesarean section (n= 371) had an increased risk of poor outcome [odds ratio (OR) 1.47, p= 0.037] after adjustment for body mass index, parity and weight discordance. There was no increased risk for poor outcome in monochorionic (MC) twins with intended vaginal delivery (n= 63) compared with planned cesarean section (n= 52; OR 0.87, 95% confidence interval 0.26-2.96). Nulliparity increased the risk of poor outcome in DC (OR 1.5, p= 0.03) and in MC twins (OR 4.01, p= 0.02), as well as birthweight discordance >300 g (DC, OR 1.50, p= 0.02; and MC, OR 6.02, p= 0.002). For DC twins, we found a significantly higher risk of poor outcome of the second-born twin compared with the first (OR 1.64, p= 0.001).
  
  
  CONCLUSIONS
  Dichorionic twins born after 36 weeks of gestation had a higher risk of poor outcome by intended vaginal delivery than by planned cesarean section. For MC twins, statistical differences in outcome by mode of delivery could not be seen.
authors.affiliation: Department of Obstetrics and Gynecology, Roskilde University Hospital, Denmark. elisehoffmann@gmail.com
authors.forename: Elise
authors.initials: E
authors.lastname: Hoffmann
authors.forename: Anna
authors.initials: A
authors.lastname: Oldenburg
authors.forename: Line
authors.initials: L
authors.lastname: Rode
authors.forename: Ann
authors.initials: A
authors.lastname: Tabor
authors.forename: Steen
authors.initials: S
authors.lastname: Rasmussen
authors.forename: Lillian
authors.initials: L
authors.lastname: Skibsted
mesh_terms: D000328:Adult; D001034:Apgar Score; D002585:Cesarean Section; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000379:methods*; D005260:Female; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D015931:Intensive Care, Neonatal; D015999:Multivariate Analysis; D016017:Odds Ratio; D036801:Parturition; D011247:Pregnancy; D011256:Pregnancy Outcome; D059285:Pregnancy, Twin; D012189:Retrospective Studies; D012306:Risk; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic