title: First-trimester embryo size discordance: a predictor of premature birth following multifetal pregnancy reduction.
abstract: OBJECTIVE
  We have previously reported a correlation between the starting number of embryos for multifetal pregnancy reduction (MFPR) and discordance in size during the first trimester. Here we evaluated the correlation between the degree of discordance and length of gestation in the remaining fetuses.
  
  
  METHODS
  Observational clinical series.
  
  
  METHODS
  Academic medical center with a single physician who performs a large number of MFPRs.
  
  
  METHODS
  Analysis of 252 consecutive MFPRs from a 2.5-year period (1996-1998).
  
  
  METHODS
  MFPR for patients with multifetal pregnancies.
  
  
  METHODS
  We evaluated the correlation between the degree of discordance in embryo size, as measured by the greatest difference in crown-rump length (CRL) (delta max), and the length of gestation.
  
  
  RESULTS
  Embryo size discordance was related to length of gestation of the remaining fetuses after MFPR. Of 72 patients with a delta max >5 mm, the rate of severe premature birth (delivery at <28 weeks' gestation) was 9.7%, compared with 1.7% for patients with a delta max <5 mm (P<.01). Of patients with severe premature birth, 70% had delta max >5 mm, compared with less than 30% in patients who delivered after 28 weeks (P<.05).
  
  
  CONCLUSIONS
  Variations in embryo growth patterns in multifetal pregnancies may be observed even in the first trimester, which may be predictive of late pregnancy outcomes. With a delta max > or =5 mm, there is a significant increase in the risk of severe premature birth (delivery at <28 weeks).
authors.affiliation: Department of Obstetrics and Gynecology, Center for Fetal Diagnosis and Therapy, Wayne State University, Detroit, Michigan, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Carreno
authors.forename: Y
authors.initials: Y
authors.lastname: Yaron
authors.forename: B
authors.initials: B
authors.lastname: Feldman
authors.forename: M
authors.initials: M
authors.lastname: Treadwell
authors.forename: M A
authors.initials: MA
authors.lastname: Ayoub
authors.forename: M I
authors.initials: MI
authors.lastname: Evans
mesh_terms: D018568:Crown-Rump Length; D004622:Embryo, Mammalian / Q000033:anatomy & histology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007752:Obstetric Labor, Premature / Q000175:diagnosis*; D011247:Pregnancy; D018607:Pregnancy Reduction, Multifetal; D011272:Pregnancy, Multiple