Changes in molecular weight of hyaluronan and hyaluronidase activity in uterine cervical mucus in cervical ripening

Background. This study was undertaken to investigate changes in the forms o f hyaluronan and hyaluronidase activity in cervical mucus during cervical r ipening, Methods. Uterine cervical mucus was obtained from 57 pregnant women (25 at preterm gestation, ten at term gestation, 11 within 1 week before labor, an d 11 during the first stage of labor). We determined 1) concentration of hy aluronan, 2) hyaluronidase activity, and 3) molecular weight of hyaluronan in cervical mucus. Data are presented as mean and range. Results. The hyaluronan concentration in mucus in the Ist stage of labor (1 .58 pg/ml, 0.46-23.96) was significantly (p<0.05) higher than that in all o ther groups (preterm: 0.29, 0.10-0.88; term: 0.24, 0.11-0.80; within 1 week before labor: 0.30, 0.18-0.62). Hyaluronidase activity both within 1 week before labor group (3.03 min., 1.12-3.95) and in Ist stage of labor group ( 3.52, 0.43-5.15) was significantly (p<0.05) higher than that in preterm gro up (1.70, 0.00-5.47). The molecular weight of hyaluronan in cervical mucus in the Ist stage of labor (0.97x10(6), 0.86-1.41) was significantly (p<0.05 ) lower than in the preterm and term groups (preterm: 1.60, 1.21-2.20, term : 1.41, 1.21-2.20). There was a significant correlation between hyaluronida se activity and molecular weight of hyaluronan (p<0.05, r=-0.41, n=23). Conclusion. These findings suggest that either hyaluronidase or low-molecul ar weight hyaluronan could be one of the most important regulators in the p rocess of cervical ripening.