Urinary trypsin inhibitor suppresses premature cervical ripening

Unknown signals from the fetus are thought to be involved in the onset of parturition. We recently discovered that urinary trypsin inhibitor (UTI) from fetal urine inhibits uterine muscle contraction. Objectives: The aim of this research was to elucidate the mechanism of action of UTI in suppressing cervical maturation. Study design: Non-pregnant and pregnant rabbits pretreated with and without UTI suppositories containing 1000 U (400 μg) for 3 days were treated for 2 days with vaginal suppositories containing 100 ng of interleukin-8 (IL-8). Results: IL-8 induced softening and dilatation of the rabbit cervices. In contrast UTI inhibited IL-8 induced cervical softening and dilatation. Water content, collagen content, neutrophil counts, elastase activity and collagenase activity of the cervix were increased by IL-8, but they did not increase by IL-8 with UTI. Conclusion: These results suggest that UTI inhibits cervical maturation induced by IL-8.