REGULATION OF EARLY GESTATIONAL CORPUS-LUTEUM FUNCTION IN SPONTANEOUSAND FOLLICULAR STIMULATED CONCEPTIONS

Objective: To determine the regulatory role of hCG on P secretion in n ormal and abnormal (abortive and ectopic) first trimester pregnancies. Study Design: The number of doublings of hCG per day (1/DT; reciproca l of hCG doubling time) was correlated with serum P using linear and n onlinear models in normal intrauterine pregnancies, spontaneous aborti ons, and ectopic pregnancies (EPs) conceived spontaneously or after cl omiphene citrate (CC). Results: Linear correlations between P and 1/DT s of hCG were poor. In contrast, nonlinear modeling with a hyperbolic curve fit the data well and allowed all of the data to be included for analysis regardless of the pregnancy type. Furthermore, this model co uld be used to explain the differential P concentrations seen in norma l and abnormal first trimester pregnancies. The nonlinear hyperbolic m odel demonstrated that follicular events determine the maximal P produ ction during early gestation. Human chorionic gonadotropin 1/DTs appro ximately equal to 0.5 sustain maximal P production. Progesterone produ ction is then sustained by the rate of change of hCG. Conclusion: Nonl inear correlation analysis suggests that P production in early gestati ons is regulated by prior follicular events and the rate of hCG produc tion.