Progesterone
A steroid hormone produced by the ovaries that plays a key role in the menstrual cycle, pregnancy, and embryonic development. Progesterone production is regulated by the HPG axis and is affected by GnRH-based therapies used in fertility treatment, endometriosis, and other reproductive conditions.
Technical Context
Progesterone is produced by the corpus luteum after ovulation and by the placenta during pregnancy. It transforms the endometrium from proliferative to secretory phase, preparing for implantation, and maintains pregnancy. Progesterone is regulated by LH and is suppressed by GnRH-based therapies. In IVF protocols, GnRH agonist triggers (administering a single GnRH agonist dose to trigger the LH surge for final oocyte maturation instead of hCG) reduce the risk of ovarian hyperstimulation syndrome. Progesterone supplementation is typically required after GnRH agonist trigger because the resulting LH surge is shorter than an hCG trigger.