Amniotic membrane collagen content and type distribution in women with preterm premature rupture of the membranes in pregnancy.

Amniotic membrane samples were taken following preterm delivery from 15 women with preterm prelabour rupture of the membranes (PPROM) and 14 with unrelated reasons, and from 25 delivering at term. Fibrillar collagens were extracted and analysed by interrupted gel electrophoresis. Collagens were decreased in PPROM relative to controls, but showed similar sub-type distribution, with one exception. In this case an increased ratio of Type I to Type III collagen was observed, with normal collagen content. In conclusion, PPROM is accompanied by generalised reduction in amnion collagen content, involving all fibrillar sub-types monitored. This may reflect general changes in protease activity or in collagen expression in affected membranes.