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What is Oestrogen

Estrogen or oestrogen is the main female sexual hormone, which is responsible for the regulation and development of the female reproductive system, along with secondary sexual characteristics.

Oestrogen is a hormone, which is secreted by the ovaries. Oestrogen or estrogen makes two things occur:

  1. It stops the production of FSH (follicle stimulating hormone) to ensure that only one egg matures during the 28 ­day cycle of a woman
  2. Oestrogen is also responsible for stimulating the hormone LH – which is the Lutenising Hormone.

In women, oestrogen is generated primarily in the ovaries, however it’s also created by fat cells as well as the adrenal gland.

1. Oestrogen during the onset of puberty

In the onset of puberty, oestrogen plays a part in the growth of so­ called secondary sex characteristics, like breasts, pubic hair and arm­pit hair. Estrogen also helps to control the menstrual period, controlling how your uterine lining grows, throughout the initial part of the cycle.

2. Fertilisation

During cycles when the woman’s egg isn’t fertilised, oestrogen levels fall dramatically and menstruation starts. However the egg is fertilised, oestrogen works with progesterone, another of your hormones, to stop ovulation during pregnancy.
Oestrogen - Women

3. Placenta & oestrogen

During pregnancy, the placenta produces oestrogen, specifically the bodily hormone estriol. Estrogen controls lactation along with other changes in your breasts, including at adolescence and throughout pregnancy.

4. Other roles of oestrogen

This hormone has a part to play in many bodily function. It plays a part in blood clotting, as well as maintaining the thickness and strength of your vaginal wall and your urethal lining. It is also important for maintaining vaginal lubrication.

Oestrogen is instrumental in bone development, working with vitamin D, calcium along with other hormones to efficiently break down and reconstruct bones in accordance with the body’s natural processes. As oestrogen levels start to fall in middle­age, the procedure for rebuilding bones is therefore less efficient, with post­menopausal females finally breaking down more bone than they create. This is why postmenopausal females are 4 times more likely to have problems with osteoporosis than men.

It changes skin, hair, mucous membranes and the pelvic muscles, according to Johns Hopkins Medicine. Oestrogen also has an impact on your mind, and studies also show that chronically low oestrogen levels are connected with a decreased mood.

Men produce oestrogen as well, but at lower amounts than females. Estrogen in men is secreted by the adrenal glands and by the testes. In guys, oestrogen is believed to influence sperm count.

5. Changes in oestrogen levels

There are various times through the life of a person when oestrogen levels might change. For instance, oestrogen levels normally rise during puberty and throughout pregnancy. Estrogen levels fall after menopausal, or when a female stops menstruating. This reduction in oestrogen production may cause symptoms like hot flashes, vaginal dryness and loss of sex drive. Estrogen levels also fall after childbirth. Extreme exercise and anorexia may also result in a decrease in oestrogen levels because girls with low body fat might not be capable of producing adequate amounts of estrogen.


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All articles on the blog and website are intended as information only. Please do not consider any of the information provided here as a substitute for medical advice. At all times seek medical advice directly with your own doctor and medical team.


This website was formerly Merrion Fetal Health. The clinic has undergone a rebrand and is now known as Merrion Ultrasound.