title: Maternal serum progesterone-induced blocking factor at 11-13 weeks' gestation in spontaneous early preterm delivery.
abstract: OBJECTIVE
  Progesterone-induced blocking factor (PIBF) may be the mediator of the pregnancy maintenance effects of progesterone. The aim of this study is to investigate the potential value of measuring the maternal serum concentration of PIBF at 11-13 weeks' gestation in the prediction of spontaneous early preterm delivery.
  
  
  METHODS
  The maternal serum concentration of PIBF at 11-13 weeks was measured by enzyme-linked immunosorbent assay in 25 singleton pregnancies which subsequently delivered spontaneously before 34 weeks, and 75 controls who delivered at or after 37 weeks. The values in the 2 groups were compared by the Mann-Whitney U test.
  
  
  RESULTS
  The median maternal serum concentration of PIBF in women who subsequently delivered before 34 weeks (157.5, interquartile range 99.5-208.8 ng/ml) was not significantly different from the control group delivering at term (167.5, interquartile range 105.0-212.0 ng/ml; p = 0.519).
  
  
  CONCLUSIONS
  In women who have a spontaneous early preterm delivery, the maternal serum levels of PIBF are not altered at 11-13 weeks of gestation.
authors.affiliation: Harris Birthright Research Centre of Fetal Medicine, King's College Hospital, London, UK.
authors.forename: Jarek
authors.initials: J
authors.lastname: Beta
authors.forename: Julia
authors.initials: J
authors.lastname: Szekeres-Bartho
authors.forename: Evdoxia
authors.initials: E
authors.lastname: Skyfta
authors.forename: Ranjit
authors.initials: R
authors.lastname: Akolekar
authors.forename: Kypros H
authors.initials: KH
authors.lastname: Nicolaides
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000097:blood / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011257:Pregnancy Proteins / Q000097:blood*; D011261:Pregnancy Trimester, First / Q000097:blood; D011374:Progesterone / Q000097:blood; D013491:Suppressor Factors, Immunologic / Q000097:blood*
chemical_list: C110058:PIBF1 protein, human; D011257:Pregnancy Proteins; D013491:Suppressor Factors, Immunologic; D011374:Progesterone