Structural characteristics of term human fetal membranes prior to labour: identification of an area of altered morphology overlying the cervix

Premature rupture of fetal membranes can have serious clinical implications , especially for the initiation of preterm labour and its consequences. To account for this phenomenon many studies have attempted to identify membran e features that may be uniquely associated with the site of rupture. Our pr evious work has identified an area of the fetal membrane, following spontan eous term birth which exhibits alterations consistent with structural weakn ess. The aim of this study was to determine if these changes existed prior to labour, In formalin-fixed paraffin-embedded tissue sections an area of t he fetal membrane overlying the cervix, termed the 'cervical membranes', wa s characterized by an increased thickness of the connective tissue layer (2 15% increase, P < 0.01) and decreased thickness of both the cytotrophoblast (36% reduction, P < 0.01) and decidual layers (64% reduction, P < 0.01) co mpared to the rest of the membrane,This resulted in the cervical membranes being significantly thinner (P < 0.05) than the rest of the membrane. Simil ar changes were also detected in frozen sections of fetal membranes, These regional differences have two important implications in that: (i) the cervi cal membrane may represent a region of structural weakness susceptible to r upture during labour, and (ii) the paracrine relationships between fetal me mbranes and the myometrium may be qualitatively affected within different r egions of the uterus.