title: Modifiable risk factors for growth restriction in twin pregnancies.
abstract: OBJECTIVE
  This study was undertaken to evaluate modifiable risk factors for adverse fetal growth in twin pregnancies.
  
  
  METHODS
  A large cohort study from a database of women with twin gestations identified at risk for preterm labor was performed. Examining each infant's birth weight and gestational age at delivery, infants were classified as being average (AGA), large (LGA), or small (SGA) for gestational age, using the Alexander reference curve. Clinical and demographic factors were compared between patients delivering at least 1 SGA infant and AGA pairs using Pearson's chi2 Student t test statistics and logistic regression.
  
  
  RESULTS
  There were 11,827 twin pregnancies evaluated. Risk factors associated with SGA deliveries included tobacco abuse, poor weight gain, lean prepregnancy body mass index, African American race, and nonmarried. The logistic regression identified tobacco abuse as the single greatest risk for poor fetal growth, (odds ratio [OR] 1.95; 95% CI [1.68, 2.27]). Weight gain of less than one-half lb/wk also increased SGA risk (OR 1.35; 95% CI [1.16, 1.68]), whereas weight gain greater than 1 lb/wk decreased SGA risk (OR 0.77; 95% CI [0.68, 0.86]).
  
  
  CONCLUSIONS
  Tobacco abuse and weight gain are the modifiable risk factors, which require intervention during a twin pregnancy. Patients should be encouraged to stop tobacco abuse and gain a minimum of one-half lb/wk in the later half of pregnancy to minimize the risk for growth restriction.
authors.affiliation: Department of Obstetrics and Gynecology, University of Kentucky, Lexington, USA.
authors.forename: Wade D
authors.initials: WD
authors.lastname: Schwendemann
authors.forename: John M
authors.initials: JM
authors.lastname: O'Brien
authors.forename: John R
authors.initials: JR
authors.lastname: Barton
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Milligan
authors.forename: Niki
authors.initials: N
authors.lastname: Istwan
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D014427:Twins; D015430:Weight Gain