Progesterone is a key hormone primarily involved in the female reproductive system, with several important functions:
- It prepares the endometrium (lining of the uterus) for a fertilized egg to implant and grow by thickening the uterine lining and stimulating glandular and blood vessel development, creating a supportive environment for pregnancy
- If fertilization does not occur, progesterone levels drop, leading to the shedding of the endometrium during menstruation
- If pregnancy occurs, progesterone production continues (initially by the corpus luteum, later by the placenta) to maintain the uterine lining, support early pregnancy, and prevent further ovulation during pregnancy
- Progesterone also decreases uterine irritability, suppresses the maternal immune response to fetal antigens to prevent rejection, and helps trigger lactation later in pregnancy
- Beyond reproduction, progesterone has roles in brain function and neuroprotection, reducing inflammation and excitotoxicity after brain injury, aiding neuroregeneration, and influencing skin elasticity, bone strength, respiration, and smooth muscle relaxation
- In males, progesterone is produced by the adrenal glands and is involved in sperm development
In summary, progesterone is essential for regulating the menstrual cycle, supporting pregnancy, and has broader physiological effects including neuroprotection and immune modulation
