title: Progression of cervical dilatation in normal human labor is unpredictable.
abstract: BACKGROUND
  The aim of this study was to analyze how the progression of cervical dilatation in active labor can be predicted by digital assessment in low-risk pregnant women, in spontaneous labor at term.
  
  
  METHODS
  This prospective observational study was performed on 328 women with singleton term gestations experiencing midwife-led labor according to local protocols, progressing to full dilatation and spontaneous delivery without any medical intervention. Mixed nonlinear models were adopted to (i) model individual cervical data into centile curves and (ii) calculate the time needed to gain 1 cm in cervical dilatation (TNG1cm ) modeled as a function of current dilatation. We correlated the first and the last TNG1cm on parturients with at least four cervical data points.
  
  
  RESULTS
  TNG1cm showed large variations, both before and after 6 cm. This variability of natural progression of cervical curves described by the 10th and 90th centiles exceeded the differences observed in published curves from cohorts homogeneous for parity, weight and ethnicity. There was no significant correlation between the first and the last TNG1cm . Neonatal base excess was not significantly different in women with TNG1cm <10th centile and >90th centile.
  
  
  CONCLUSIONS
  The rate of cervical dilatation, traced by parsimonious nonlinear mixed models, is largely unpredictable in the case of spontaneous naturally progressing labor, even when possible larger individual variability is excluded by prudent clinical rules. Future research in labor and delivery should be focused on the diagnosis of the causes that lie behind apparently erratic cervical changes.
authors.affiliation: Department of Woman, Mother and Neonate, Buzzi Children's Hospital, Milan, Italy.|Biomedical and Clinical Sciences School of Medicine, University of Milan, Milan, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Ferrazzi
authors.affiliation: Department of Clinical and Community Sciences, Medical Statistics and Biometry, University of Milan, Milan, Italy.
authors.forename: Silvano
authors.initials: S
authors.lastname: Milani
authors.affiliation: Department of Woman, Mother and Neonate, Buzzi Children's Hospital, Milan, Italy.|Biomedical and Clinical Sciences School of Medicine, University of Milan, Milan, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Cirillo
authors.affiliation: Department of Woman, Mother and Neonate, Buzzi Children's Hospital, Milan, Italy.|Biomedical and Clinical Sciences School of Medicine, University of Milan, Milan, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Livio
authors.affiliation: Department of Woman, Mother and Neonate, Buzzi Children's Hospital, Milan, Italy.|Biomedical and Clinical Sciences School of Medicine, University of Milan, Milan, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Piola
authors.affiliation: Department of Woman, Mother and Neonate, Buzzi Children's Hospital, Milan, Italy.|Biomedical and Clinical Sciences School of Medicine, University of Milan, Milan, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Brusati
authors.affiliation: Department of Woman, Mother and Neonate, Buzzi Children's Hospital, Milan, Italy.|Biomedical and Clinical Sciences School of Medicine, University of Milan, Milan, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Paganelli
mesh_terms: D000328:Adult; D020070:Cervical Ripening / Q000502:physiology; D002584:Cervix Uteri / Q000502:physiology*; D004106:Dilatation; D005260:Female; D006801:Humans; D007747:Labor Stage, First / Q000502:physiology; D007743:Labor, Obstetric / Q000502:physiology*; D016014:Linear Models; D011247:Pregnancy; D011446:Prospective Studies
keywords: Cervical dilatation; delivery; labor curve; low-risk labor; parturition