title: Improved Perinatal Mortality in Twins--Changing Practice and Technologies.
abstract: OBJECTIVE
  We set out to examine rates of perinatal mortality in twin pregnancies over a 17-year study period. Changes in mode of delivery were also examined as well as causes of death in twin mortalities.
  
  
  METHODS
  This retrospective cohort study was performed at three large tertiary referral centers from 1996 to 2012. It included all normally formed twin infants with a birth weight more than 500 g. All cases of perinatal mortality in twin pregnancies (infants more than 500 g who suffered an intrauterine or early neonatal (≤ 7 days of age) death were recorded. The changing rate of cesarean delivery as well as varying causes of death in twins over the course of the study were also examined.
  
  
  RESULTS
  During the study period, there were 395,830 pregnancies across the three institutions, this included 6,727 twin gestations. The perinatal mortality rate was 21.5/1,000 twin infants. The perinatal mortality rate in twins decreased over the study period (p = 0.0006; R (2) = 0.55; slope = -1.2). Rates of cesarean delivery in twin gestations were found to have increased over the course of the study (p < 0.0001; R (2) = 0.84; slope = 1.7). There were 288 intrauterine and early neonatal deaths in twin infants, 50% (147/288) occurred in twins born extremely premature (< 26 weeks). Prematurity was the leading cause of mortality in twins, followed by twin-to-twin transfusion syndrome (TTTS). TTTS was found to have a decreasing contribution to perinatal mortality during the study (p = 0.008; R (2) = 0.38; slope = -1.5).
  
  
  CONCLUSIONS
  The perinatal mortality rate in twins improved during the study. The rate of cesarean delivery increased by 1.7% for each year of the study, culminating in a cesarean delivery rate of 62% in 2012. TTTS made a decreasing contribution to the mortality rate in twins during the study.
authors: RCSI Academic Unit, Obstetrics and Gynaecology, Dublin, Ireland.
authors: Mark P
authors: MP
authors: Hehir
authors: Rotunda Hospital, Dublin, Ireland.
authors: Aoife
authors: A
authors: Mctiernan
authors: Coombe Womens and Infants University Hospital, Dublin, Ireland.
authors: Aisling
authors: A
authors: Martin
authors: National Maternity Hospital, Dublin, Ireland.
authors: Stephen
authors: S
authors: Carroll
authors: Rotunda Hospital, Dublin, Ireland.
authors: Ronan
authors: R
authors: Gleeson
authors: RCSI Academic Unit, Obstetrics and Gynaecology, Dublin, Ireland.
authors: Fergal D
authors: FD
authors: Malone
mesh_terms: D001724:Birth Weight; D002585:Cesarean Section / Q000639:trends*; D005260:Female; D005330:Fetofetal Transfusion / Q000401:mortality*; D005865:Gestational Age; D006801:Humans; D052577:Infant, Extremely Low Birth Weight; D007231:Infant, Newborn; D007494:Ireland; D016014:Linear Models; D008297:Male; D054238:Perinatal Mortality / Q000639:trends*; D011247:Pregnancy; D011256:Pregnancy Outcome; D059285:Pregnancy, Twin / Q000706:statistics & numerical data*; D012189:Retrospective Studies