The force required to rupture fetal membranes paradoxically increases with acute in vitro repeated stretching.
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.
Pandey
Vishal
V
Department of Pediatrics, MetroHealth Medical Center, Cleveland, OH 44109, USA.
Jaremko
Kellie
K
Moore
Robert M
RM
Mercer
Brian M
BM
Stetzer
Bradley
B
Kumar
Deepak
D
Fox
Jennifer M
JM
Mansour
Joseph M
JM
Moore
John J
JJ
D005321:Extraembryonic Membranes / Q000293:injuries / Q000502:physiology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D011247:Pregnancy; D012421:Rupture; D013718:Tensile Strength