Serum collagenase levels during pregnancy and parturition

Recent studies have described the origin of the collagenase responsible for the degradation and loss of collagen during cervical ripening and dilatation to be polymorphonuclear leukocytes. In the present study the clinical feature of cervical dilatation was correlated to the serum levels of human granulocyte collagenase. The serum collagenase level was measured in 19 premenopausal women and in 181 pregnant women. In 15 of these pregnant women serum samples were obtained from the onset of labour to the active phase of labour at four different times. The collagenase concentrations remained low up to the 35th week of gestation (19.4 ng/ml) in comparison with the beginning of pregnancy. From the 35th week of gestation on we found a slight increase in collagenase in maternal serum. The maximum peak was reached during parturition at a cervical dilatation of 6-8 cm (71.2 ng/ml). The serum levels returned to non-pregnant values the first day following delivery. The results show that collagenases are critically involved in parturition.