title: Fetal growth rates and the very preterm delivery of twins.
abstract: OBJECTIVE
  Our objective was to determine whether slow fetal growth rates and twin growth patterns from 20 weeks' gestation to delivery are associated with very preterm delivery.
  
  
  METHODS
  Available charts were reviewed for twin pregnancies, delivered between 1979 and 2002, at 4 U.S. medical centers. The sample of 1612 pregnancies delivered at 28 week's gestation or greater and had at least 2 ultrasound evaluations of fetal size from 20 to 28 weeks or from 28 weeks to delivery for estimation of fetal growth rates (grams per week). Slow fetal growth (below the 10th percentile) was defined as less than 90 grams per week at 20-28 weeks and 168 g/week from 28 weeks to delivery. The main outcome measure was the timing of delivery.
  
  
  RESULTS
  Of the women delivering twins, 5.3% delivered extremely preterm (28-30 weeks), 8.5% very preterm (31-32 weeks), and 40.1% preterm (33-36 weeks). Patterns of growth for the pair were highly associated with very preterm delivery. Compared with neither growing slowly (1.7%), 4.9% delivered very preterm if only 1 twin grew slowly. Very preterm was 14.6% (adjusted odds ratio 9.81; 95% confidence interval, 3.50-27.48) with both growing slowly from 28 weeks on and 20.0% (adjusted odds ratio 15.04; 95% confidence interval 5.13-44.11) with both growing slowly over both intervals. Survival analyses indicated that twins with normal growth in both intervals remained undelivered for a significantly longer number of days (P < .0001) than pairs in which one or both twins were growing slowly.
  
  
  CONCLUSIONS
  Very preterm delivery of twins seems to be preceded by slowed or compromised fetal growth for the pair.
authors.affiliation: Division of Epidemiology, Statistics and Prevention Research, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-7510, USA. hedigerm@exchange.nih.gov
authors.forename: Mary L
authors.initials: ML
authors.lastname: Hediger
authors.forename: Barbara
authors.initials: B
authors.lastname: Luke
authors.forename: Victor H
authors.initials: VH
authors.lastname: Gonzalez-Quintero
authors.forename: Dibe
authors.initials: D
authors.lastname: Martin
authors.forename: Clark
authors.initials: C
authors.lastname: Nugent
authors.forename: Frank R
authors.initials: FR
authors.lastname: Witter
authors.forename: Jill G
authors.initials: JG
authors.lastname: Mauldin
authors.forename: Roger B
authors.initials: RB
authors.lastname: Newman
mesh_terms: D004200:Diseases in Twins / Q000453:epidemiology; D005317:Fetal Growth Retardation / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D012307:Risk Factors