title: Birth weight is lower for survivors of the vanishing twin syndrome: a case-control study.
abstract: OBJECTIVE
  To compare the outcome of singleton pregnancies originating from a twin gestation with singleton pregnancies originating from a single gestation.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Women's general hospital in Austria.
  
  
  METHODS
  A total of 794 singleton deliveries after IVF/intracytoplasmic sperm injection, including 46 survivors of vanishing twin syndrome (study group) and 92 matched singletons (control group).
  
  
  METHODS
  None.
  
  
  METHODS
  Data concerning duration of gestation, mode of delivery, birth weight, neonatal intensive care unit admission, duration of hospitalization, perinatal mortality.
  
  
  RESULTS
  Of all singletons born, 5.8% originated from a twin gestation. Mean (+/- SD) birth weight was significantly higher in the control group (2876.3 +/- 600.5 g vs. 3249.6 +/- 624.5 g). The frequency of low birth weight (26.1% vs. 12.0%) and being small for gestational age (32.6% vs. 16.3%) was significantly lower in the control group. No differences were observed in terms of duration of gestation.
  
  
  CONCLUSIONS
  A higher risk for lower birth weight and being small for gestational age for survivors of the vanishing twin syndrome was found. Such pregnancies need to be carefully monitored, and parents must be informed about the associated risks when transferring more than one embryo.
authors.affiliation: IVF Unit, Landesfrauen- und Kinderklinik, and Department of Gynecology, Allgemeines Krankenhaus, Linz, Austria. omar.shebl@gespag.at
authors.forename: Omar
authors.initials: O
authors.lastname: Shebl
authors.forename: Thomas
authors.initials: T
authors.lastname: Ebner
authors.forename: Michael
authors.initials: M
authors.lastname: Sommergruber
authors.forename: Andreas
authors.initials: A
authors.lastname: Sir
authors.forename: Gernot
authors.initials: G
authors.lastname: Tews
mesh_terms: D000030:Abortion, Missed; D000328:Adult; D001724:Birth Weight; D016022:Case-Control Studies; D004200:Diseases in Twins; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects; D005327:Fetal Resorption; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D011247:Pregnancy; D011256:Pregnancy Outcome; D011272:Pregnancy, Multiple; D020554:Sperm Injections, Intracytoplasmic / Q000009:adverse effects; D014427:Twins