title: The force required to rupture fetal membranes paradoxically increases with acute in vitro repeated stretching.
abstract: OBJECTIVE
  The purpose of this study was to determine whether acute repetitive stretching causes fetal membranes (FM) weakening.
  
  
  METHODS
  Cesarean or vaginally delivered FM were repeatedly stretched and thereafter subjected to rupture testing. Rupture strength (RS), work to rupture (WR), and stiffness were determined. Unstretched FM were compared with stretched FM.
  
  
  RESULTS
  In the cesarean group, FM stretched to 50% or 75% of the baseline (unstretched) RS for 10-20 cycles of 10 seconds each paradoxically showed increased RS and stiffness. WR decreased compared with baseline. Detailed analysis revealed that even a single stretch cycle initiated these changes to physical properties. Vaginally delivered FM showed similar changes in physical properties, as did separated amnion.
  
  
  CONCLUSIONS
  Acute stretch forces do not directly cause FM weakening.
authors.affiliation: Department of Pediatrics, MetroHealth Medical Center, Cleveland, OH 44109, USA.
authors.forename: Vishal
authors.initials: V
authors.lastname: Pandey
authors.forename: Kellie
authors.initials: K
authors.lastname: Jaremko
authors.forename: Robert M
authors.initials: RM
authors.lastname: Moore
authors.forename: Brian M
authors.initials: BM
authors.lastname: Mercer
authors.forename: Bradley
authors.initials: B
authors.lastname: Stetzer
authors.forename: Deepak
authors.initials: D
authors.lastname: Kumar
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Fox
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Mansour
authors.forename: John J
authors.initials: JJ
authors.lastname: Moore
mesh_terms: D005321:Extraembryonic Membranes / Q000293:injuries / Q000502:physiology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D011247:Pregnancy; D012421:Rupture; D013718:Tensile Strength