Suboptimal progesterone production in pathologic pregnancies

Serum progesterone (P) levels were determined at the time of routine prenatal registration (227 patients) or upon presentation for evaluation of vaginal bleeding and/or abdominopelvic cramping/pain (135 patients). P associated with a normal intrauterine gestation was 24.63 +/- 4.19 (SD) ng/mL as compared with 6.29 +/- 2.43 ng/mL and 6.02 +/- 2.39 ng/mL for spontaneous abortions and ectopic gestations, respectively. Further, P differed between asymptomatic (11.92 +/- 9.61 ng/mL) and symptomatic patients (4.81 +/- 3.92 ng/mL) who were subsequently shown to have an abnormal gestation. By establishing a P cutoff point of < or = 14.2 ng/mL and < or = 10.5 ng/mL in asymptomatic and symptomatic patients, respectively, 100% screening sensitivity was reached, and therefore no abnormal gestations would escape detection in our study population. P was either in the normal or abnormal range as early as four weeks' estimated gestational age and persisted as such through the luteal-to-placental shift and up to the time of pregnancy loss or 12 weeks' estimated gestational age. Although there was no significant correlation between P and chorionic gonadotropin levels and pregnancy outcome, the binding constant for native chorionic gonadotropin was 15-52 times lower in 12 of 41 cases of spontaneous abortion but not ectopic gestation, suggesting a possible molecular basis for suboptimal P production. P is therefore an excellent adjunctive marker for prediction of early pregnancy outcome, and in some cases qualitative abnormalities in chorionic gonadotropin may dictate its production.