title: Early pregnancy threshold vaginal pH and Gram stain scores predictive of subsequent preterm birth in asymptomatic women.
abstract: OBJECTIVE
  The study was undertaken to identify early pregnancy vaginal markers predictive of subsequent preterm birth.
  
  
  METHODS
  In a multicenter Bacterial Vaginosis (BV) Trial, 21,554 women were screened with a vaginal pH and of these, two populations were studied. These included 12,041 who had a pregnancy outcome in the database and 6838 women who had a vaginal pH of 4.5 or greater and a Gram stain score and a pregnancy outcome in the database. ColorpHast Indicator Strips were used to determine the vaginal pH and the Nugent criteria were used to determine a vaginal Gram stain score of 0 to 10.
  
  
  RESULTS
  Delivery at <37, <35, or <32 weeks' gestation was similar for women with a vaginal pH of less than 4.4 or 4.7 (P not significant) but was increased in women with a pH of 5.0 (P =.04,.02,.03, respectively) or with a pH of 5.0 or greater (at each gestational age P <.0001). The effect of pH of 5.0 or greater was similar for women who had a spontaneous preterm birth at each gestational age (P <.0001) or birth weight of less than 2500 g or less than 1500 g (P <.0005). Women with a vaginal pH of 4.5 or greater and a Gram stain score of 9 to 10 (compared with 0-8) had increased preterm births at <37, <35, and <32 weeks' gestation (P <.01), and birth weights less than 2500 g (P <.0001) or less than 1500 g (P <.01). Women whose vaginal pH was 5.0 or greater had a higher prevalence of vaginal fetal fibronectin > or =50 ng/mL (P <.0001), but the proportion of women with a vaginal fetal fibronectin > or =50 mg/mL did not differ by Gram stain score.
  
  
  CONCLUSIONS
  Women with a vaginal pH of 5.0 or greater or a vaginal pH of 4.5 or greater and a Gram stain score of 9 to 10 had significantly increased preterm births at <37, <35, and 32 weeks' gestation and/or a birth weight less than 2500 g or less than 1500 g.
authors.affiliation: Department of Obstetrics and Gynecology, University of Alabama at Birmingham, 35249, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Hauth
authors.forename: Cora
authors.initials: C
authors.lastname: Macpherson
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Carey
authors.forename: Mark A
authors.initials: MA
authors.lastname: Klebanoff
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Hillier
authors.forename: J M
authors.initials: JM
authors.lastname: Ernest
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Leveno
authors.forename: Ronald
authors.initials: R
authors.lastname: Wapner
authors.forename: Michael
authors.initials: M
authors.lastname: Varner
authors.forename: Wayne
authors.initials: W
authors.lastname: Trout
authors.forename: Atef
authors.initials: A
authors.lastname: Moawad
authors.forename: Baha
authors.initials: B
authors.lastname: Sibai
mesh_terms: D004056:Differential Threshold; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D005544:Forecasting; D005840:Gentian Violet; D006801:Humans; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D007234:Infant, Premature; D036801:Parturition; D010619:Phenazines; D011247:Pregnancy / Q000378:metabolism*; D014621:Vagina / Q000378:metabolism*
chemical_list: D005353:Fibronectins; C035863:Gram's stain; D010619:Phenazines; D006859:Hydrogen; D005840:Gentian Violet