Isolation and Characterization of 5α-Pregnane-3, 20-dione and Progesterone in Peripheral Blood of Pregnant Women

Abstract

5Α-Pregnane-3,20-dione and progesterone were isolated from a pregnancy plasma pool and were identified by using a combination of chromatographic techniques and mass spectrometry. Antibodies to progesterone were obtained in rabbits by immunization with progesterone-1Α-carboxyethyl-thioether-thyroglobulin. The raised antibodies were of high affinity and one of them cross-reacted (137%) with 5Α-pregnane-3,20-dione. This property was used to develop radioimmunoassays for measuring circulating levels of both progesterone and 5Α-pregnane-3,20-dione in pregnancy plasma. The levels of both progesterone and 5Α-pregnane-3,20-dione increase throughout pregnancy, but a highly significant increase is observed only after the 32nd week of gestation.