GLOSSARY

Progesterone is a steroid hormone secreted mainly by the ovarian corpus luteum after ovulation and, in pregnancy, by the placenta. Its name means “for gestation”, and its main role is to prepare and maintain the uterus for pregnancy.

Pattern of Secretion

• Follicular phase: progesterone is low.
• Luteal phase: it rises after ovulation and peaks about 7 days later; measuring it at this time is used to confirm ovulation.
• Pregnancy: from about weeks 8–10, the placenta becomes its main source.

Main Effects