Oestrogen is one of two sex hormones that a woman possesses. The other is progesterone. We normally associate testosterone with men, but women need it, too. Oestrogen is beneficial to a woman in many ways, including enabling her to have a menstrual period, get pregnant and carry a child to term. It is also good for the skin, hair and virtually every organ in her body. However, oestrogen can get too high, and when it does this is considered oestrogen dominance. This term is the invention of the late Dr. John Lee, who did extensive research in progesterone and its relationship to oestrogen.
When a woman's body is functioning optimally, oestrogen levels aren't too high or too low. Oestrogen peaks as a woman prepares for her menstrual period. During this time, a woman may experience PMS or premenstrual symptom because of the increase in oestrogen. Oestrogen levels decline once ovulation occurs, at which time progesterone is produced and takes over. When a woman stops ovulating regularly, as she heads toward menopause, progesterone production is sporadic. Progesterone is not made if ovulation does not occur. As a consequence, there is nothing to keep oestrogen levels in check, which is one of the services that progesterone provides. When progesterone isn't present, oestrogen levels can skyrocket, resulting in oestrogen overload.
When a woman is pregnant, her oestrogen levels are supposed to be high. When she is not pregnant, high levels of oestrogen can result in night sweats, mood swings, tender and sore breasts, sleep disruptions and hot flashes---the typical peri-menopausal symptoms. High levels of oestrogen are a common occurrence during peri-menopause and this results in oestrogen dominance or overload.
A woman's oestrogen levels can also be impacted by outside influences, reports WomenToWomen.com. Man-made chemicals that are defined as xenoestrogens are present in the environment. Xenoestrogens can disrupt our endocrine system. When oestrogen levels get too high, because of xenoestrogens or naturally, this can cause breast cancer, infertility and autoimmune disorders.
High oestrogen levels can also be caused by ovarian hyper-stimulation syndrome (OHSS), according to Clarian.org. This is sometimes the result of when a woman takes fertility drugs to stimulate egg production.
If a woman has a functioning adrenocortical tumour, this can produce too much oestrogen, as well as too much testosterone, cortisol and aldosterone.
The Cleveland Clinic reports that too much oestrogen in a woman can result in menstrual bleeding after the woman has gone through menopause and irregular menstrual periods in women who have yet to go through menopause.