Edgar Allen identified and outlined the role of female sex hormones and discovered estrogen in the early 1900s in the US. In 1923, Allen, through his research with mice, isolated the

Katharina Dorothea Dalton was a physician in England in the twentieth century who defined premenstrual syndrome (PMS) as a cluster of symptoms suspected to begin one to two weeks before menstruation and disappear upon the onset of a new menstrual cycle. Prior to Dalton, there was little research on pre-menstrual issues and those that existed linked the problem to excessive water

George Nicholas Papanicolaou developed the Pap test in the United States during the twentieth century. The Pap test is a diagnostic procedure used to test for cervical cancer in women. Papanicolaou's work helped improve the reproductive health of women by providing an effective means of identifying precancerous cells and improving the likelihood of early treatment and survival of cervical cancer.

Estrogen is the primary sex hormone in women and it functions during the reproductive menstrual cycle. Women have three major types of estrogen: estrone, estradiol, and estriol, which bind to and