title: Prospective risk of fetal death in singleton, twin, and triplet gestations: implications for practice.
abstract: OBJECTIVE
  To evaluate the prospective risk of fetal death in singleton, twin, and triplet pregnancies and to compare this risk with fetal and neonatal death rates.
  
  
  METHODS
  We analyzed 11,061,599 singleton, 297,622 twin, and 15,375 triplet gestations drawn from the 1995-1998 National Center for Health Statistics linked birth and death files. Prospective risk of fetal death was expressed as a proportion of all fetuses still at risk at a given gestational age and compared with fetal death rate. Fetal death risk and neonatal death rates were represented graphically for singletons, twins, and triplets.
  
  
  RESULTS
  The prospective risk of fetal death at 24 weeks was 0.28 per 1000, 0.92 per 1000, and 1.30 per 1000 for singletons, twins, and triplets, respectively. At 40 weeks, the corresponding risk was 0.57 per 1000 and 3.09 per 1000 for singletons and twins, respectively and, at 38 or more weeks, 13.18 per 1000 for triplets. Plots of gestation-specific prospective risk of fetal death and neonatal mortality converged for singletons and twins at term but crossed for triplets at approximately 36 weeks' gestation.
  
  
  CONCLUSIONS
  Prospective risk of fetal death is greater for triplets and twins than for singletons and greater for triplets than for twins during the third trimester. The pattern corroborates with uteroplacental insufficiency as a suspected underlying mechanism. When prospective risk of fetal death exceeds neonatal mortality risk, delivery might be indicated. When this model is used, this data set suggests that it might be reasonable to consider delivery of twins by 39 weeks and triplets by 36 weeks to improve perinatal outcome.
authors.affiliation: Department of Obstetrics and Gynecology, University of Colorado, Denver, Colorado, USA.
authors.forename: Bronwen
authors.initials: B
authors.lastname: Kahn
authors.forename: L H
authors.initials: LH
authors.lastname: Lumey
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Zybert
authors.forename: John M
authors.initials: JM
authors.lastname: Lorenz
authors.forename: Jane
authors.initials: J
authors.lastname: Cleary-Goldman
authors.forename: Mary E
authors.initials: ME
authors.lastname: D'Alton
authors.forename: Julian N
authors.initials: JN
authors.lastname: Robinson
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005313:Fetal Death / Q000517:prevention & control; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D010927:Placental Insufficiency; D011247:Pregnancy / Q000706:statistics & numerical data*; D011248:Pregnancy Complications / Q000401:mortality* / Q000517:prevention & control*; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012307:Risk Factors; D014310:Triplets / Q000706:statistics & numerical data; D014427:Twins / Q000706:statistics & numerical data; D014481:United States / Q000453:epidemiology