The Metabolic Clearance Rate and Uterine Extraction of Progesterone at Midgestation

Abstract
The blood metabolic clearance rate of progesterone at midgestation, measured by the continuous infusion method, is 3450 ± 194 (SE) 1/day. The concentration of [3H]progesterone in the uterine venous blood was not significantly different from the [3H]progesterone in the antecubital venous blood and it is concluded that the uterine extraction of circulating progesterone at midgestation or term is negligible. Indirect estimates of the uterine blood flow in 3 women at midgestation ranged from 131 to 367 ml/min.