Correlation of cervical progesterone levels to plasma progesterone levels in normal pregnancy and preterm labor: A cross-sectional study

Background: The theory of “functional progesterone withdrawal” explains the role of progesterone prior to delivery. Previous studies mentioned the existence of progesterone regulation in the cervix that plays a role in maintaining the integrity of the cervix and cervical ripening. Cervical progesterone levels relate to activities of progesterone at the cervix, compared to its amount in circulation. The objective of this study was to measure cervical mucus progesterone levels and its correlation to plasma progesterone levels in pregnancy. Methods: : This was a cross-sectional study conducted in January-September 2010 at Persahabatan Hospital. The subjects were pregnant women in the 28 th – 34 th weeks of gestational age. In total, 72 subjects who met the criteria were divided into normal pregnancy group and preterm labor group. The cervical and plasma progesterone levels were measured using The Advia Centaur® Progesterone kit, which is a commercial immunoassay with direct chemiluminescence method. Results: : There was a positive correlation (r=0.539) between cervical progesterone levels with plasma progesterone levels in the preterm labor group. There was no correlation between cervical progesterone levels with plasma progesterone levels in the normal pregnancy group. Conclusion:  This study showed that cervical progesterone levels could be measured through cervical mucus. A significant positive correlation was found by this study between cervical progesterone levels and plasma progesterone levels in the preterm labor group.  This study is expected to provide new insights for understanding the metabolism and the role of progesterone in maintaining cervical integrity during pregnancy, and its relation to prevention of preterm birth.