What Is Estrogen? How Does It Work?

You don’t need to be an endocrinologist to know about estrogen. But what exactly does the so-called “female hormone” actually do? Let’s run through the basics of this chemical messenger, and what roles it plays in the female body.

What is estrogen?


Estrogen is one of the main hormones of the female reproductive cycle. The body produces it in a three-step chain reaction of different hormones:

  • Step 1: The hypothalamus section of the brain releases GnRH (Gonadotropin Releasing Hormone), which acts on the pituitary gland.

  • Step 2: The pituitary gland responds to the GnRH by releasing FSH (Follicle Stimulating Hormone). FSH wakes up about 10 to 20 of the dormant egg-containing follicles in the ovaries and tells them to start developing for ovulation.

  • Step 3: As the follicles come online, they start producing estrogen. Estrogen supports the follicle development, as well as causing the lining of the uterus to thicken.

Let’s clear up some terminology, though. Technically, there are three main types of estrogen: estrone (E1) , estradiol (E2) and estriol (E3). Estradiol is the most powerful, and it’s the main one which works during your fertile years.

What does estrogen do?

In women, estrogens has a number of effects:

  • Gives a curvier physique with fat deposits building on the chest, butt and hips
  • Supports ovarian follicle development
  • Helps the implantation of fertilized eggs in the womb by thickening the uterine lining
  • Promotes psychological and brain functioning
  • Strengthens bones and suppresses vasoconstriction
  • Produces cervical mucus to make the vagina more hospitable to sperm cells
  • Causes basal body temperature (BBT) to decline

How do estrogen levels change over the menstrual cycle?

menstrual cycle hormone level

The production of estrogen rises and falls according to different phases of the menstrual cycle. Estrogen levels begin to rise towards the end of your menstrual period to get your body ready to support a pregnancy, then peak just before ovulation. This also correlates with the time in your cycle when you’re feeling physically and emotionally stable. A little while after ovulation, estrogen levels decline as you enter the luteal phase. Estrogen levels are very low just before your next period. As your period arrives, estrogen levels start climbing back up again, and the cycle begins anew.

What role does estrogen play during pregnancy?

pregnant belly

For a fertilized egg to successfully latch onto the uterine lining and establish a pregnancy, your body needs one more hormone on the job: progesterone. Progesterone and estrogen work together to support the physical changes of pregnancy, and they continue to stay elevated up until the baby is born. Some of their many roles include expanding the womb to accommodate the fetus, and developing the mammary glands to prepare for breastfeeding.

Once the baby is delivered, the levels of these two hormones plummet over the space of about two days. Alongside triggering hair loss and skin changes, this means a huge drop in neurotransmitters like serotonin. This is thought to be one of the contributing factors in post-partum depression.

What happens to estrogen during menopause?

Estrogen kicks in for the female body around puberty, but hormone levels begin to decline by the time a woman is around her 40s. This happens because of diminishing ovarian supply. The hypothalamus and pituitary gland keep sending out the hormonal messengers telling to ovaries to develop follicles, but there’s a finite number of ovarian follicles. When they start to run out with age, there’s less estrogen output from the ovaries.

This can result in the following symptoms as women approach and enter menopause:

  • Palpitations and hot flashes
  • Stiff shoulders
  • Forgetfulness
  • Irritability and depression
  • Changes in fat distribution
  • Breast changes
  • Increased risk of osteoporosis
  • Painful urination

Healthy lifestyle brings healthy hormone balance!

woman exercise stretch

Estrogen plays a big role in keeping your body healthy. Aside from puberty and reproduction, it helps maintain strong bones and prevent cardiovascular problems. What’s more, even though we tend to think of it as a “female” hormone, everyone has estrogen in their system, regardless of sex.

Lifestyle factors like poor diet or an unhealthy lifestyle can throw your hormone balance out of whack, and if this continues, it may contribute to health and fertility problems. If you think your estrogen levels aren’t quite where they ought to be, speak to your doctor. There’s not much you can do about age-related ovarian decline, but taking steps towards a healthy lifestyle can help maintain a healthy hormone balance.