Disappearance of serum progesterone: after normal delivery and removal of hydatidiform mole.

Serum progesterone was measured by competitive protein binding assay at regular intervals up to 24 hours after delivery in 4 normal pregnancies. In 6 cases of hydatidiform mole, serum progesterone was assayed before and at regular intervals up to 48 hours after uterine evacuation or hysterectomy. Serum progesterone dropped rapidly by more than 50% during the first hour postpartum, and it was less than 25% of the predelivery levels 24 hours after parturition. In all 6 cases of molar pregnancies, serum progesterone fell rapidly within the first few hours after uterine evacuation. In the presence of theca lutein cysts (2 cases), serum progesterone fell much more slowly than in the absence of theca lutein cysts after removal of the mole tissue. Serum progesterone was less than 5mg/ml after total hysterectomy of uterine evacuation in moles without theca lutein cysts. These findings suggest that while the placenta is the principal source of elevated serum progesterone in normal pregnancy, the molar trophoblast is the principal source of elevated serum progesterone in hydatidiform mole, with the theca lutein cysts making a contribution when they are present.