How Does the Placenta Produce Progesterone

Pregnenolone is converted to progesterone by type 1 3beta-hydroxysteroid dehydrogenase located in the mitochondrion. Progesterone synthesis by the human placenta displays notable differences from steroid synthesis in the classical steroid producing tissues such as the adrenal cortex and corpus luteum.

When does the placenta make progesterone?

During the early stages of pregnancy, progesterone is still produced by the corpus luteum and is essential for supporting the pregnancy and establishing the placenta. Once the placenta is established, it then takes over progesterone production at around weeks 8-12 of pregnancy ‘luteo-placental shift’.

Does the placenta always produce enough progesterone?

In natural pregnancies, at around seven weeks the placenta will make all the progesterone needed for a woman to stay pregnant. Even if you removed the ovaries and stopped all progesterone, the women won’t have an increased risk of miscarriage!