Serum collagenase levels in relation to the state of the human cervix during pregnancy and labor.

Abstract

The purpose of our study was to investigate the role of collagenase in the cervical ripening and dilatation process in term pregnancy. Serum samples were obtained from nonpregnant women (n = 5) and term-pregnant women. The term-pregnant women were either admitted for elective cesarean section or labor induction (unfavorable cervix, n = 19; favorable cervix, n = 12) or in spontaneous, active labor (stiff and inelastic cervix, n = 7; soft compliant cervix, n = 8). Statistical analysis was performed with the Student t test. The nonpregnant women had low serum collagenase levels (5.2 +/- 0.7 micrograms collagen digested per minute per 100 ml serum, mean +/- SEM). At term but before labor, women with unripe cervices had higher collagenase levels (10.3 +/- 0.9). The women with ripe cervices had even higher serum collagenase levels (22.9 +/- 4.2; p < 0.001). During labor, women with stiff and inelastic cervices had lower serum collagenase levels compared with women with soft and compliant cervices (12.9 +/- 1.7 vs 28.0 +/- 4.2; p < 0.01). Serum collagenase during ripening at term and in active labor increases, supporting its active role in the ripening process.