title: Gestational age of previous twin preterm birth as a predictor for subsequent singleton preterm birth.
abstract: OBJECTIVE
  We sought to determine an optimal gestational-age cutoff of preterm twin deliveries for predicting subsequent singleton preterm birth (PTB).
  
  
  METHODS
  We performed a retrospective study of women with a spontaneous twin delivery who subsequently had a singleton gestation. Univariate and multivariate analyses determined the risk of a spontaneous singleton PTB after a PTB of a twin gestation. Different gestational-age cutoffs of the previous twin PTB were evaluated.
  
  
  RESULTS
  Among 255 women, previous twin PTB at <34 weeks' gestation was associated with an increased risk of singleton PTB (odds ratio, 9.67; 95% confidence interval, 3.07-30.47). Every twin gestational age cutoff at <34 weeks' gestation had a significantly higher risk of subsequent singleton PTB, which was no longer significant at ≥ 34 weeks' gestation (odds ratio, 1.68; 95% confidence interval, 0.23-12.19).
  
  
  CONCLUSIONS
  In women with a previous spontaneous twin PTB at <34 weeks' gestation, there is an increased risk of subsequent singleton PTB. A twin birth at ≥ 34 weeks' gestation is not associated with an increased risk for a subsequent singleton PTB.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Jefferson Medical College of Thomas Jefferson University Hospital, Philadelphia, PA, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Rafael
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Hoffman
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Leiby
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Berghella
mesh_terms: D000328:Adult; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007752:Obstetric Labor, Premature / Q000209:etiology*; D011237:Predictive Value of Tests; D011247:Pregnancy; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000209:etiology*; D012189:Retrospective Studies; D012306:Risk; D012307:Risk Factors