Medline ® Abstract for Reference 18

The disappearance of chorionic gonadotropin from the circulation was studied in a group of 10 healthy mothers and their offspring following vaginal delivery. Kinetic analysis revealed the following biexponential clearance characteristics: in mothers the rapid half-life component averaged 4.75 +/- 0.58 (SE) hours (n = 6), and the slow half-life component averaged 32.2 +/- 1.35 hours (n = 6); in neonates the respective overall means were 1.32 and 55.2 hours. Total elimination of chorionic gonadotropin (less than 0.005 IU/ml) occurred at a median time of 14 days following birth (range, 8 to 24 days) in mothers and at 1.5 days (range, 0 to 4 days) in neonates.