The complex mechanisms behind membrane rupture remain poorly understood, presenting a problem for clinicians attempting to predict and prevent preterm births. In particular, there is a lack of information in the literature about the protein content of the chorion. This thesis establishes a characterization of the protein content of the chorionic layer of the fetal membranes and examines differing protein content across different regions of the membranes (proximal to and distal from the rupture site) and between membranes with differing modes of rupture (spontaneous versus artificial). A more thorough understanding of membrane rupture in both term and preterm cases is required to improve diagnostic methods and prevent PPROM.

Fetal membranes were collected from term, vaginal deliveries with no known pregnancy-related complications. Samples were collected from spontaneously rupturing (SROM;​ n=5) and artificially rupturing (AROM;​ n=2) membranes. For each membrane, samples were taken proximal to and distal from the rupture initiation site. Mass spectrometry identified several proteins involved in assembly, wound response and immune response as differentially expressed between the placental and rupture regions. In particular, basement membrane proteins including fibrillin and laminin were observed exclusively in the artificially rupturing samples, and fibrinogen was found in the rupture region in AROM but not SROM samples. Talin and vinculin, proteins involved in focal adhesions, were observed exclusively in AROM rupture.

Collagen content was analyzed by hydroxyproline assay. No difference in collagen concentration was observed based on mode of rupture or region. These results were supported by histology. Sulfated glycosaminoglycan content was quantitated by DMMB assay. Within the placental region, sGAG content was significantly reduced in SROM samples. Within each mode of rupture group, no regional difference in sGAG content was seen, although a pairwise reduction that did not reach significance was observed for the rupture region for most samples. Safranin O stained histology slides appeared to show an increase in proteoglycan content in rupture, which may be due to an increase in the non-sulfated GAG hyaluronan. Finally, a consistent, but not significant, pairwise increase in chorion thickness was seen in the rupture region.