title: Evaluation of the pregnancy prolongation index (PPI) as a measure of success of obstetric interventions in the prevention of preterm birth and associated morbidities.
abstract: OBJECTIVE
  This study was undertaken to evaluate the validity of the pregnancy prolongation index (PPI) as a measure of preterm labor treatment success.
  
  
  METHODS
  Analysis of prospectively collected maternal and neonatal data from a national clinical database (Matria Healthcare). Included were patients with singleton, twin, and triplet pregnancies who had outpatient surveillance initiated between 18 and 34 weeks and delivered at 24 to 36 6/7 weeks' gestation with NICU admission. Each patient's PPI score was calculated via the following equation: [(gestational age at delivery - gestational age at start of treatment) / (37.0 - gestational age at start of treatment)] x 100%. The impact of increasing PPI score was measured against NICU length of stay as a surrogate gauge of neonatal morbidity. Data were further stratified by gestational type and reason for delivery.
  
  
  RESULTS
  Pregnancy outcomes of 12,642 patients (6,642 singletons, 4,326 twins, and 1,674 triplets) were analyzed. The PPI score increased in a direct, inverse linear relationship with decreasing number of NICU days.
  
  
  CONCLUSIONS
  The PPI is a sensitive measure for the evaluation of treatment success in the inhibition of preterm labor and delivery.
authors.affiliation: Department of Obstetrics and Gynecology, California-Pacific Medical Center, San Francisco, 94118, USA. funglammd@aol.com
authors.forename: Fung
authors.initials: F
authors.lastname: Lam
authors.forename: Niki B
authors.initials: NB
authors.lastname: Istwan
authors.forename: Debbie
authors.initials: D
authors.lastname: Rhea
authors.forename: Martha
authors.initials: M
authors.lastname: Smith
authors.forename: Elliott
authors.initials: E
authors.lastname: Main
authors.forename: Terri
authors.initials: T
authors.lastname: Slage
authors.forename: Gary
authors.initials: G
authors.lastname: Stanziano
mesh_terms: D000328:Adult; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D007902:Length of Stay; D011237:Predictive Value of Tests; D011247:Pregnancy / Q000502:physiology* / Q000706:statistics & numerical data; D011256:Pregnancy Outcome; D011272:Pregnancy, Multiple / Q000502:physiology / Q000706:statistics & numerical data; D011273:Pregnancy, Prolonged; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology