title: Mode of delivery and the risk of delivery-related perinatal death among twins at term: a retrospective cohort study of 8073 births.
abstract: OBJECTIVE
  To determine the risk of perinatal death among twins born at term in relation to mode of delivery.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Scotland 1985-2001.
  
  
  METHODS
  All twin births at or after 36 weeks of gestation, excluding antepartum stillbirths and perinatal deaths due to congenital abnormality (n= 8073).
  
  
  METHODS
  The outcome of first and second twins was compared using McNemar's test and the outcome of twin pairs in relation to mode of delivery was compared using exact logistic regression.
  
  
  METHODS
  Intrapartum stillbirth or neonatal death of either twin.
  
  
  RESULTS
  Overall, there were six deaths of first twins and 30 deaths of second twins (OR for second twin 5.00, 95% CI 2.00-14.70). The odds ratio for death of the second twin due to intrapartum anoxia was 21 (95% CI 3.4-868.5). The associations were similar for twins delivered following induction of labour and for sex discordant twins. However, there was no association between birth order and the risk of death among 1472 deliveries by planned caesarean section. There was death of either twin among 2 of 1472 (0.14%) deliveries by planned caesarean section and 34 of 6601 (0.52%) deliveries by other means (P= 0.05, odds ratio for planned caesarean section 0.26 [95% CI 0.03-1.03]). The association was similar when adjusted for potential confounders. Assuming causality, we estimate that 264 caesarean deliveries (95% CI 158-808) would be required to prevent each death.
  
  
  CONCLUSIONS
  Planned caesarean section may reduce the risk of perinatal death of twins at term by approximately 75% compared with attempting vaginal birth. This is principally due to reducing the risk of death of the second twin due to intrapartum anoxia.
authors.affiliation: Department of Obstetrics and Gynaecology, Cambridge University, UK.
authors.forename: Gordon C S
authors.initials: GC
authors.lastname: Smith
authors.forename: Imran
authors.initials: I
authors.lastname: Shah
authors.forename: Ian R
authors.initials: IR
authors.lastname: White
authors.forename: Jill P
authors.initials: JP
authors.lastname: Pell
authors.forename: Richard
authors.initials: R
authors.lastname: Dobbie
mesh_terms: D000328:Adult; D001722:Birth Order; D002585:Cesarean Section; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000009:adverse effects / Q000401:mortality*; D005260:Female; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D008423:Maternal Age; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology; D014427:Twins