Estrogen vs. Progesterone — What's the Difference?

Estrogen and progesterone play critical roles in a woman's reproductive system, but they serve different primary functions. Estrogen, with its derivatives estradiol, estrone, and estriol, is predominantly responsible for developing and regulating the female reproductive system. It's involved in the regulation of the menstrual cycle and the development of secondary sexual characteristics during puberty. Progesterone, on the other hand, chiefly focuses on preparing the body for pregnancy after ovulation and sustaining the uterus throughout pregnancy.

Estrogen levels generally fluctuate throughout the menstrual cycle. They surge before ovulation, promoting the maturation of the ovarian follicles. This hormone also aids in maintaining bone density and regulating cholesterol levels in the body. Progesterone, contrastingly, sees its peak after ovulation. It helps to thicken the lining of the uterus, making it receptive to a fertilized egg.

In terms of synthesis, estrogen is primarily produced in the ovaries but also in the adrenal glands and fat tissues. It's vital for sexual development, especially during the teenage years. Progesterone is mainly secreted by the corpus luteum in the ovary and, in larger amounts, by the placenta during pregnancy. Its main task is ensuring the lining of the uterus is suitable for a fertilized egg.