Estrogens are a group of the most important female sex hormones. They play an important role in controlling the female menstrual cycle and also in pregnancy.
There are different types of estrogens that are grouped together under the name of estrogen. The most important ones are Estrone (E1), Estradiol (E2), Estriol (E3) and Estetrol (E4). They are mainly produced in the ovaries, but also in the adrenal cortex. During pregnancy, the placenta also produces estrogens (around the 9th week of pregnancy).
Although they belong to the female sex hormones, the male testicles also produce estrogens, but only in very small quantities. In girls, estrogens are responsible for the development of secondary sexual characteristics and the female reproductive organs, the high voice and the typical female curves from the beginning of puberty.
What effect does estrogen have?
Estrogen plays an important role in the female cycle, especially in the first half of the cycle. Put simply, estrogens create the conditions for a possible pregnancy in women. This is why the estrogen level rises continuously in the first half of the cycle. During this time the uterine lining, which was expelled with the last menstrual bleeding, is rebuilt (proliferation) and well supplied with blood.
At the same time, the quality and consistency of the cervical mucus changes from initially lumpy to viscous to glassy and watery in the days before ovulation - the estrogen has then reached its highest level. The cervical mucus now has the ideal consistency for the sperm to be able to move particularly well in it towards the fallopian tube.
The cervix opens under the influence of estrogen so that the sperm can pass through it. Around the time of ovulation, the hormones cause the uterus to contract slightly, and their suction effect helps the sperm to move towards the uterus. What's more, the follicle that is dominant in the respective cycle produces particularly high levels of estrogen, thus intensifying the contractions of the muscles of the uterus - the sperm are directed to its side of the fallopian tube.
Estrogen signals the pituitary gland that the egg cell is mature and thus indirectly triggers ovulation.
In the second half of the cycle, the lining of the uterus thickens further. In this way, estrogen ensures optimal implantation conditions, provided that a fertilized egg really does successfully implant itself in the uterine wall. If this is the case, the estrogen level remains high.
During pregnancy, estrogen is responsible, among other things, for the enlargement of breast tissue and the onset of lactation. But it also has other tasks:
- Stimulation of the formation of new blood vessels.
- It increases the blood flow
- It increases the elasticity of the blood vessels
- It lowers the blood sugar level and improves glucose tolerance
- It increases the sensitivity of the uterus to progesterone in late pregnancy
- It leads to well moistened skin and mucous membranes
- It promotes the uterine muscles' readiness to contract during birth
How your estrogen level changes during the cycle
In the first half of the cycle, your body prepares for pregnancy. A large part of this is due to estrogen. At the beginning of the new cycle and during menstruation the estrogen level is still constantly low but about a week before ovulation it slowly increases. This increase is mainly due to the Follicle Stimulating Hormone (FSH), which also increases. Together with the Luteinizing hormone (LH), the FSH allows follicles (follicles) in the ovary to mature, each containing one egg cell. The follicles in turn stimulate the production of estrogens. Up to ovulation, the levels of FSH, LH and estrogens increase, and around the time of ovulation they peak.
After ovulation, the estrogen initially drops sharply, but then rises again and remains high throughout the second half of the cycle. If pregnancy has not occurred, the estrogen level does not drop again until shortly before menstruation.
Pro tip: If you want to monitor your FSH and LH levels throughout your cycle and watch them as they go up and down you should check out the Pearl Fertility app!
Estrogen production in pregnancy
During pregnancy, the production of estrogens increases massively: the levels of estriol and estrone increase by a hundred times and the levels of estradiol even by a thousand times. This increase happens extremely rapidly and the amount of estrogen produced in a single day during pregnancy is just as high as that produced by a non-pregnant woman within three years.
In early pregnancy only estrone and estradiol are initially increased. From around the 9th week of pregnancy, the child's adrenal glands begin to function the placenta to produce estriol itself. Once the embryo has implanted itself in the uterine wall, the embryo and the placenta are the main suppliers of estrogen.
A low level of estriol in maternal blood can therefore indicate malformations or other disorders. For example, estriol is measured in the triple test, a method of prenatal diagnostics for detecting chromosomal defects. A low value indicates disorders.
General effect of estrogen
Estrogens are significantly involved in the bone/calcium metabolism. In countries where foods containing phytoestrogens (plant substances that are similar to the hormone in their effect) are frequently served, osteoporosis occurs comparatively rarely. The disease is associated with low levels of estrogen which is because estrogen ensures that calcium is stored in the bones. If the estrogen level drops, bone density decreases because less calcium can be absorbed.
Estrogens also have an influence on the water-binding capacity of the skin and mucous membrane. For example, the high concentration of estrogen in the body is the reason why pregnant women often have particularly "plump" and fine skin, whereas conversely, when the menopause sets in, the skin of many women can become very dry. In general, estrogen is considered the "female beauty hormone".
In adults the hormone stimulates the sex drive. Estrogen also has a positive effect on fat metabolism.
Your estrogen levels when taking birth control
All of the processes described and the effect of estrogen during the cycle do not or only differently occur when you are taking the contraceptive pill or using another hormonal contraceptive.
The conventional contraceptive pill contains estrogens and progestins. Progestins are synthetically produced hormones that are similar to progesterone in their action. Taking them prevents ovulation and the hormones responsible for changes in the cycle remain at a constant level.
Variants of hormonal contraceptives such as the contraceptive pill, the mini-pill, the three-month injection and the hormone stick do not contain estrogen, only progestins. This means that the mucus plug, which normally liquefies during the fertile days and allows the sperm to pass through, remains firm and closed.
The lining of the uterus does not build up properly, so that even in the case of fertilization, implantation is very unlikely. Depending on the type and dosage of the progestins, ovulation either takes place or not. Hormonal birth control can also lead to unwanted side effects such as depression or loss of libido- if you notice such symptoms it is recommended to talk to your health care professional or OB/GYN with whom you can determine if there is a hormone free alternative for you to use for contraception.
Estrogen and menopause
With increasing age, it becomes more and more frequent that ovulation does not occur. This often results in estrogen dominance, because the follicle continues to produce estrogen but not progesterone. As a result, longer periods without bleeding occur more and more frequently, often ending in very heavy menstrual bleeding - a clear sign of the beginning of the menopause.
It is only years later that the body also stops producing estrogen. The "typical" menopausal symptoms such as dry skin and mucous membranes, hot flushes and sweating, mood swings and sleep disturbances can occur.
👉Curious, what some of your key fertility hormones are up to all the time? Go check out our hormone tracking system and get to know your hormones like never before!