SERUM COLLAGENASE LEVELS IN RELATION TO THE STATE OF THE HUMAN CERVIX DURING PREGNANCY AND LABOR

OBJECTIVE: The purpose of our study was to investigate the role of collagenase in the cervical ripening and dilatation process in term pregnancy. STUDY DESIGN: 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. RESULTS: The nonpregnant women had low serum collagenase levels (5.2 +/- 0.7 mug 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). CONCLUSION: Serum collagenase during ripening at term and in active labor increases, supporting its active role in the ripening process.