Collagen content of human amniotic membranes: effect of gestation length and premature rupture.

The collagen content of amniotic membranes was measured in samples obtained at delivery from patients with and without premature rupture of the membranes (PROM). In samples from patients with PROM the collagen content (343 microgram/mg) was significantly lower than in samples from patients without PROM (373 microgram/mg) (P less than .005). The collagen content decreased between 32 and 40 weeks' gestation from 446 to 362 microgram/mg (r = .588; P less than .001) in patients without PROM and from 393 to 332 microgram/mg (r = -.362; P less than .05) in patients with PROM. The latent period between membrane rupture and delivery was not associated with a decrease in collagen content. The changes in amnion collagen during gestation and the differences observed with PROM suggest that weakening of the amnion in preparation for rupture may be determined partly by factors controlling the synthesis and degradation of collagen.