A human in vivo model for the luteoplacental shift.

Overview

OBJECTIVE: To study the onset of early placental steroidogenesis in humans. DESIGN: Ovarian failure patients who were administered a constant dosage of exogenous estradiol (E2) and progesterone (P) during the luteal phase and early gestation and who conceived after transfer of donated oocytes were used to assess serum hormonal changes throughout early pregnancy. SETTING: Hormonally replaced ovarian failure patients undergoing an egg donation program in an academic research environment. PATIENTS, PARTICIPANTS: Nine human volunteers desiring egg donation. INTERVENTIONS: Replacement of E2 and P. MAIN OUTCOME MEASURE: Serum E2 and P concentrations were measured weekly throughout the patients' gestations. RESULTS: Serum E2 and P levels of these patients remained low in early gestation but significantly increased 25 +/- 1.6 and 34 +/- 1.6 days post embryo transfer, respectively. Regression lines of E2 (r = 0.99; P less than 0.01) and P (r = 0.95; P less than 0.005), intersected basal hormonal levels approximately 3 weeks after transfer. CONCLUSION: This estimate of the onset of placental steroidogenesis is equal to the 5th gestational week as calculated by the patients' last menses, approximately 3 weeks earlier than previously reported.