title: Twin-to-twin delivery time interval: influencing factors and effect on short-term outcome of the second twin.
abstract: BACKGROUND
  Following vaginal delivery of the first twin, the further management to deliver the second twin is in dispute. Controversial discussions have taken place on the importance of the time interval between the birth of the first and the second twin.
  
  
  OBJECTIVE
  To evaluate factors influencing twin-to-twin delivery time interval, and short-term outcome of the second twin in a complete population-based cohort in Hesse, Germany. Study design. In a population-based cohort study, between January 1990 and December 2004, all twin pregnancies of > or =34+0 weeks' gestation with a vaginally delivered first twin were evaluated. Pregnancies with intrauterine death of either one of the twins before the onset of labour, complicated by twin-twin transfusion or fetal malformations were excluded. Some 4,110 twin pregnancies were analysed. Maternal and fetal characteristics for an increased twin-to-twin delivery time interval and its impact on an adverse short-term neonatal outcome, and the effect of the twin-to-twin delivery interval on umbilical arterial pH and base excess of the second twin have been investigated.
  
  
  RESULTS
  In univariate analysis, breech, transverse lie, birth weight discordance with the second twin > or =20% larger, fetal distress, vaginal operative delivery, and caesarean section were associated with an increased time interval. Maternal characteristics were not related to an increased time interval. Increasing time interval was related to a decline in the mean umbilical arterial pH and base excess, and fetal acidosis, Apgar score <7 after 1, 5 and 10 min. In multivariate analysis, birth weight discordance, mode of delivery, and twin-to-twin delivery time interval were associated with an adverse short-term outcome of the second twin.
  
  
  CONCLUSIONS
  As twin-to-twin delivery time interval seems to be an independent risk factor for adverse short-term outcome of the second twin, it should be kept short.
authors.affiliation: Department of Gynecology and Obstetrics, Georg-August-University, Göttingen, Germany. werner.stein@med.uni-goettingen.de
authors.forename: Werner
authors.initials: W
authors.lastname: Stein
authors.forename: Björn
authors.initials: B
authors.lastname: Misselwitz
authors.forename: Stefan
authors.initials: S
authors.lastname: Schmidt
mesh_terms: D000328:Adult; D001034:Apgar Score; D001722:Birth Order; D001724:Birth Weight; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000379:methods*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D011247:Pregnancy; D011272:Pregnancy, Multiple; D013997:Time Factors; D014427:Twins; D014470:Umbilical Cord