Prostaglandin dehydrogenase in the placenta before and after the onset of labour.

Inactivation of prostaglandins in the placenta was studied using an assay for 15-hydroxy-prostaglandin dehydrogenase (PGDH). Forty-four patients with normal single pregnancies between 38 and 42 weeks gestation were studied. Placentae were obtained before the onset of labour in 9, after spontaneous labour in 18, and after oxytocin-induced labour in 17 cases, PGDH-activity ranged from 54 to 495 nanomoles PGF2alpha/g placenta/minute, with a mean +/- SEM of 207 +/- 18 nanomoles/g/minute. The results indicate that the PGDH content of the human placenta does not change markedly with the onset or during the process of labour. The length of either spontaneous or oxytocin-induced labour was not influenced by the PGDH content of the placenta.