title: The effect of early fetal losses on twin assisted-conception pregnancy outcomes.
abstract: OBJECTIVE
  To evaluate the effect of first trimester fetal losses on twin births from assisted reproductive technology (ART).
  
  
  METHODS
  Historical cohort study.
  
  
  METHODS
  Clinic-based data.
  
  
  METHODS
  The study population included 9,036 twin pregnancies of >or=22 weeks' gestation in the 2005 Society for Assisted Reproductive Technology Clinic Outcomes Reporting System database, categorized by the presence of three versus two fetal heartbeats on early ultrasound.
  
  
  METHODS
  None.
  
  
  METHODS
  Length of gestation and birthweight. Adjusted odds ratios (AORs) were calculated with the group with two fetal heartbeats on early ultrasound as the reference.
  
  
  RESULTS
  Increased odds with three fetal heartbeats included <32 weeks, 32-36 weeks, and <37 weeks (AORs 1.47, 1.28, and 1.35, respectively) and very low birthweight (<1,500 g), moderately low birthweight (1,500-2,499 g), and low birthweight (<2,500 g) (AORs 1.69, 1.38, and 1.47, respectively). Significantly decreased odds included term birth (>or=37 weeks) and nonlow birthweight (>or=2,500 g) (AORs 0.74 and 0.68).
  
  
  CONCLUSIONS
  Early fetal loss in assisted-conception pregnancies that result in a twin live birth is associated with significantly increased risks for lowered birthweight and shortened gestation. Because first-trimester multiple fetal heartbeats are more common in ART pregnancies, this factor may help explain the greater risk for reduced birthweight and shorter gestations observed in this population.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, Michigan 48824, USA. lukeb@msu.edu
authors.forename: Barbara
authors.initials: B
authors.lastname: Luke
authors.forename: Morton B
authors.initials: MB
authors.lastname: Brown
authors.forename: David A
authors.initials: DA
authors.lastname: Grainger
authors.forename: Judy E
authors.initials: JE
authors.lastname: Stern
authors.forename: Nancy
authors.initials: N
authors.lastname: Klein
authors.forename: Marcelle I
authors.initials: MI
authors.lastname: Cedars
mesh_terms: D000328:Adult; D001724:Birth Weight; D015331:Cohort Studies; D005260:Female; D005313:Fetal Death; D006340:Heart Rate, Fetal; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D008423:Maternal Age; D008875:Middle Aged; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000523:psychology*; D011261:Pregnancy Trimester, First; D011263:Pregnancy Trimester, Third; D012016:Reference Values; D027724:Reproductive Techniques, Assisted / Q000523:psychology*; D014427:Twins; D016216:Ultrasonography, Prenatal