Estrogen can be defined as a female sex hormone which is produced in the ovary and is responsible for development of female sexual characteristics. It is compound of hormone comprising of three parts: estrone, estradiol and estriol. Estrogen plays an important role in menstrual cycle.

 Estrogen hormone is present in both male as well as in female but the amount of estrogen that is present in women is far more as compared to that in male.

Estrogen hormone is responsible for developing secondary characteristics in female such as breast development, widening of pelvis, and increase in the deposition of fat in the buttock area, thigh and area of hip. It brings thickness of the endometrium and prepares the uterus for pregnancy duration. LH and FSH are the two hormones which are responsible for controlling the flow of estrogen in the women who are ready for ovulation. Developing egg follicles in the ovaries generate estrogen.

Placenta and corpus leteum are also responsible for production of estrogen hormone. Once the women passes into menopause stage then ovaries does not produce estrogen and the only source of estrogen in the body is the stored fat. Some of the organ system of the body which is affected by estrogen is cardiovascular systems, musculoskeletal and brain.