Initiation of human parturition. IX. Progesterone metabolism by placentas of early and late human gestation

L. Milewich, N. F. Gant, B. E. Schwarz, G. T. Chen, P. C. Macdonald

Research output: Contribution to journalArticle

33 Scopus citations


In in vitro studies it was found that, in the presence of added NADPH, the human placenta metabolizes progesterone to 20α-hydroxy-4-pregnen-3-one at increasing rates as pregnancy advances. A fivefold increase in 20α-hydroxysteroid oxidoreductase activity is observed in term placentas compared with the enzymic activity of placentas of 12 to 20 wk gestation (368 ± 53 pmoles/mg protein/hr vs 71 ± 8pmoles/mg protein/hr). The 5α-reductase and 3β-hydroxysteroid oxidoreductase activities were similar in placentas obtained from early and late human pregnancies.

Original languageEnglish (US)
Pages (from-to)278-280
Number of pages3
JournalObstetrics and Gynecology
Issue number3
Publication statusPublished - 1978


ASJC Scopus subject areas

  • Obstetrics and Gynecology

Cite this