The fetal membrane surrounds the fetus during pregnancy and is a thin tissue composed of
two layers, the chorion and the amnion.
While r
upture of this membrane normally
occurs at
term
, preterm rupture can result
in increased risk of fetal mortality and morbidity, as well as
danger of infection in the mother.
Although
structural changes have been observed in the
membrane in such cases, the mechanical behaviour of
the huma
n
fetal membrane
in vivo
remains poorly understood
and is challenging to investigate experimentally
.
Therefore
,
the
objective
of this study
wa
s
to d
evelop
simplified
finite element models to
investigate
the
mechanical behaviour
and rupture
of the fetal mem
brane
, particularly
its constituent layers
,
under
various
physiological
conditions.
It was found that modelling the chorion and amnion
as a single layer predicts remarkably different behaviour
compared with a more anatomically
-
accurate bilayer
, significantly underestimating stress in the amnion and
under
-
predicting the
risk of
membrane rupture.
Additionally,
reductions in chorion
-
amnion interface lubrication
and chorion thickness
(
reported in cases of
preterm rupture
)
both result
ed
in increased
membrane stress. Interestingly, the inclusion of a weak zone
in the fetal membrane that has
been observed to develop overlying the cervix would likely
cause
it
to fail
at
term
,
during
labour. Finally,
these
findings support the theory that the amnion is t
he dominant structural
component of the fetal membrane and is required to maintain its integrity. The results provide
a novel insight into the mechanical effect of structural changes in the chorion and amnion
,
in
cases of both
normal and
preterm
rupture.