title: Cervical softening occurs early in pregnancy: characterization of cervical stiffness in 100 healthy women using the aspiration technique.
abstract: OBJECTIVE
  To quantitatively describe the evolution of ectocervical stiffness in normal pregnancy.
  
  
  METHODS
  The stiffness of ectocervical tissue was measured by using the aspiration method. This non-invasive technique allows to safely and objectively determine the pressure required to displace cervical tissue to a predefined deformation level (pcl ). In this prospective study, 448 aspiration measurements were carried out on pregnant women (n = 50) at each of the eight routine pregnancy consultations and on nonpregnant subjects (reference, n = 50). pcl values were grouped as nonpregnant, first, second, third trimester, and postpartum.
  
  
  RESULTS
  Stiffness in early pregnancy (first trimester) is significantly lower, by a factor >2 for the mean value than for the nonpregnant group. pcl continuously decreases during gestation, with significant differences between first and second trimester, but not between second and third trimester. After delivery, consistency is recovered to the level of early pregnancy.
  
  
  CONCLUSIONS
  The aspiration method allows an objective description of the consistency of the ectocervix during pregnancy, indicating that the tissue softens already at the beginning of gestation, transforms continuously to lower consistency in the first two trimesters, stabilizes at a low level in the third trimester, and recovers its stiffness after delivery.
authors.affiliation: Center of Mechanics, Swiss Federal Institute of Technology Zurich, Zurich, Switzerland. badir@imes.mavt.ethz.ch
authors.forename: Sabrina
authors.initials: S
authors.lastname: Badir
authors.forename: Edoardo
authors.initials: E
authors.lastname: Mazza
authors.forename: Roland
authors.initials: R
authors.lastname: Zimmermann
authors.forename: Michael
authors.initials: M
authors.lastname: Bajka
mesh_terms: D000328:Adult; D002584:Cervix Uteri / Q000502:physiology*; D004548:Elasticity / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D006262:Health; D006801:Humans; D008137:Longitudinal Studies; D049590:Postpartum Period / Q000502:physiology; D011247:Pregnancy / Q000502:physiology*; D011261:Pregnancy Trimester, First / Q000502:physiology; D011262:Pregnancy Trimester, Second / Q000502:physiology; D011263:Pregnancy Trimester, Third / Q000502:physiology; D011312:Pressure; D013396:Suction; D055815:Young Adult