title: Neonatal mortality and morbidity in vertex-vertex second twins according to mode of delivery and birth weight.
abstract: OBJECTIVE
  To assess the risk of neonatal mortality and morbidity in vertex-vertex second twins according to mode of delivery and birth weight.
  
  
  METHODS
  Data from a historical cohort study based on a twin registry in the US (1995-1997) were used. Multivariate logistic regression was used to control for maternal age, race, marital status, cigarette smoking during pregnancy, parity, medical complications, gestational age, and other confounders.
  
  
  RESULTS
  A total of 86 041 vertex-vertex second twins were classified into two groups: second twins delivered by cesarean section after cesarean delivery of first twin (C-C) (43.0%), second twins whose co-twins delivered vaginally (V-X) (57.0%). In infants of birth weight>or=2500 g group, the risks of noncongenital anomaly-related death (adjusted odds ratio (aOR): 4.64, 95% confidence interval (95% CI): 1.90, 13.92), low Apgar score (aOR: 2.39, 95% CI: 1.43, 4.14), and ventilation use (aOR: 1.31, 95% CI: 1.18, 1.47) were higher in the V-X group compared with the C-C group. No asphyxia-related neonatal deaths occurred in C-C group, whereas the incidence of this death was 0.04% in the V-X group.
  
  
  CONCLUSIONS
  The risks of neonatal mortality and morbidity are increased in vertex-vertex second twins with birth weight>or=2500 g whose co-twins delivered vaginally compared with second twins delivered by cesarean section after cesarean delivery of first twin.
authors.affiliation: OMNI Research Group, Department of Obstetrics and Gynecology, Faculty of Medicine, University of Ottawa, and Ottawa Health Research Institute, Ottawa, Canada. qyang@ohri.ca
authors.forename: Q
authors.initials: Q
authors.lastname: Yang
authors.forename: S W
authors.initials: SW
authors.lastname: Wen
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.forename: D
authors.initials: D
authors.lastname: Krewski
authors.forename: K
authors.initials: K
authors.lastname: Fung Kee Fung
authors.forename: M
authors.initials: M
authors.lastname: Walker
mesh_terms: D000328:Adult; D001034:Apgar Score; D001238:Asphyxia Neonatorum / Q000401:mortality; D001724:Birth Weight; D002585:Cesarean Section / Q000401:mortality / Q000706:statistics & numerical data; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000379:methods* / Q000401:mortality; D005006:Ethnicity; D005260:Female; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D007746:Labor Presentation; D016015:Logistic Models; D017533:Marital Status; D008423:Maternal Age; D016017:Odds Ratio; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012042:Registries; D012189:Retrospective Studies; D012907:Smoking; D014427:Twins