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Estrogen is an essential hormone for overall health — especially reproductive health. The hormone plays a key role in puberty all the way through menopause.
As people with ovaries get older, levels of estrogen fluctuate. While everybody’s unique estrogen levels will have slight variations on top of these expected changes, medication, environmental factors, and some health conditions can also have an effect.
In this article, we’ll cover what estrogen levels typically look like throughout your lifetime, as well as what happens (and why) when estrogen levels are very low or very high.
First: What is estrogen?
As one of the two major sex hormones in people with ovaries (along with progesterone), estrogen is a key factor in our reproductive health and reproductive system. It’s present in people with sperm, too, but typically to a much lesser extent.
There are three main types of estrogen the body produces:
- Estradiol (most common type produced throughout the reproductive years, which one of the hormones the Modern Fertility Hormone Test measures)
- Estriol (produced during pregnancy)
- Estrone (produced after menopause)
Your ovaries are your body’s main source of estrogen, while the adrenal glands that sit on top of the kidneys and fat tissue produce small amounts too. While estrogen has a huge impact on reproductive health, that’s not the only way it affects bodily processes. It also impacts the health of the urinary tract, heart and blood vessels, bones, muscles, breasts, hair, mucous membranes, skin, pelvic muscles, and the brain.
For this article, we’ll be focused on the estrogen that’s most related to reproductive health: estradiol. That said, we’ll be using the more colloquial “estrogen” for simplicity’s sake.
How does estrogen function in the body from puberty through menopause?
During early puberty and the first years of menstruation, estrogen and other hormone levels are rising rapidly. This is associated with irregular menstrual periods and cycle lengths at first. Dr. Jenn Conti, MD, MS, MSc, an OB-GYN and Modern Fertility medical advisor, explains: “The irregularity is technically caused by the GnRH (gonadotropin-releasing hormone, which signals hormone production from the ovaries and testes) release from the brain being not quite smooth/regular at first.”
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) stimulate ovarian follicle (the fluid-filled sacs that house eggs) growth, ovulation, and endogenous estrogen (meaning it’s produced by the body) when at this stage.
Estrogen levels rise and peak again in your early to late twenties, often resulting in more predictable periods. During perimenopause, ovulation, estrogen, and follicle growth significantly decline.
Estrogen levels during puberty
Usually starting between 8 and 13 in people with ovaries (though puberty onset around 8 years old is more notable in Black people), a part of the brain known as the hypothalamus begins to produce the hormone GnRH, stimulating the ovaries and an increase in estrogen, which eventually results in a first period (“menarche” in medical-speak).
Breast buds — a small amount of firm, tender breast tissue just under the nipple — are often the first sign of puberty. This process is launched by estrogen, which sparks the fat in connective tissue to connect and bind, causing breast enlargement and the development of breast ducts. Estrogen is also involved in the growth of pubic and underarm hair, and like we mentioned above, the start of the menstrual cycle.
Estrogen levels throughout your cycle
Once menstrual cycles begin, estrogen levels typically rise and fall twice in one cycle:
- During the follicular phase, one dominant ovarian follicle produces an increase in estrogen as it grows. These high estrogen levels signal to the brain to ramp up LH production, which triggers ovulation and can often be picked up by ovulation tests 24-48 hours before the egg’s release.
- During ovulation, estrogen levels drop.
- After ovulation and during the luteal phase, the ruptured follicle (the one that released the egg) turns into the corpus luteum. The corpus luteum ramps up estrogen levels (as well as progesterone levels) to thicken the uterine lining in preparation for a growing fetus. If the egg isn’t fertilized, the corpus luteum decays and estrogen levels drop again.
Estrogen levels after implantation
Optimal estrogen levels are essential in priming the uterus for the implantation of a fertilized embryo — however, the uterus only remains in this state for a limited amount of time each cycle. One study found a link between estrogen levels and the time the uterus remains in its ideal state for implantation. Higher estrogen levels resulted in a shorter ideal state for implantation, while lower levels resulted in a longer ideal state.
The same study highlights low in-vitro fertilization (IVF) success rates when the uterus isn’t receptive to implantation, establishing estrogen as a critical influencing factor.
Estrogen levels during pregnancy
Estrogen levels steadily rise to support growth, development, and energy during pregnancy — peaking in the third trimester. When estrogen rises more rapidly during the first trimester, these sudden higher levels may be associated with morning sickness and nausea.
Estrogen levels right before and during menopause
During the transitional stage before menopause, perimenopause, estrogen levels become erratic, with a preference toward elevation. As this first stage of menopause comes to a close, these levels become less erratic and begin to decline (eventually stabilizing) while LH and FSH start to largely increase. This overall lack of estrogen can result in vaginal dryness, loss of vaginal elasticity, and less blood supply to the genital area, as well as bone loss.
As estrogen levels drastically change in perimenopause, high levels can cause bloating, breast tenderness, and heavy bleeding. Once these levels become more consistently low, that can cause hot flashes, night sweats, mood changes, changes in fat distribution (new or growing “spare tire”), insomnia, and fatigue. At the same time, menstrual cycles are also changing as a result, making periods less predictable and fertility decline as menopause progresses.
What happens when estrogen levels are too low or too high?
Aside from expected fluctuations through puberty, menstrual cycles, perimenopause, and menopause, there are other situations where estrogen levels might drop or rise. These changes can lead to side effects that range from the physical to the emotional.
When estrogen levels are too low (aka <22.4 pg/mL)
Excluding menopause, the most common cause of low estrogen levels is an oophorectomy (surgical removal of the ovaries). They can also happen as a result of excessive exercise or disordered eating (an effect of reduced ovarian stimulation).
Pituitary gland malfunction can lead to too little or too much of some hormones (LH and FSH) and then impact estrogen levels. Hypopituitarism is when the pituitary gland doesn’t release enough LH or FSH (or both), which can cause excessively low estrogen levels and sometimes difficulties getting pregnant.
What’s considered “low”? Every lab will have their own reference range for what they deem as “low.” The Modern Fertility Hormone Test’s “normal” reference range for estradiol (an estrogen) in premenopausal people with ovaries on day 3 of their cycle (when hormone levels are baseline) is 22.4-115 picograms per milliliter (pg/mL). Anything below 22.4 pg/mL is considered “low.”
Low estrogen can lead to a number of bodily changes, including the following:
- Infrequent or disrupted periods
- Hot flashes and/or night sweats
- Sleeping issues
- Decreased sexual desire
- Mood swings
- Dry skin
- Menstrual migraines
When estrogen levels are too high (aka >115 pg/mL)
In addition to fluctuating hormone levels around puberty or perimenopause, higher estrogen levels can be caused by estrogen-producing tumors. Since body fat is one of the producers of estrogen, a higher body-fat percentage can also lead to higher estrogen levels.
On the flip side of hypopituitarism, hyperpituitarism — when the pituitary gland produces too much of one or multiple hormones — can cause excessively high estradiol levels and sometimes infertility.
What’s considered “high”? In terms of the Modern Fertility Hormone Test, levels of estradiol (an estrogen) in premenopausal people with ovaries on day 3 of their cycle are “high” if they’re above 115 pg/mL.
Symptoms of high estrogen levels include:
- Heavier periods or increased frequency of periods
- Worsening of premenstrual syndrome
- Non-cancerous breast lumps
- Uterus fibroids (Black, Asian, and Latinx people with ovaries are at an increased risk of fibroids — one study found that vitamin D supplementation caused fibroid shrinkage by reducing Estrogen Receptor 1 and specific progesterone receptors)
- Decreased sex drive
- Anxiety or depression
If you have endometriosis, high estrogen can trigger inflammation and sometimes extreme pain because the hormone controls the growth of uterine tissue. Those with polycystic ovary syndrome (PCOS) — which is often marked by high androgens (a “male” sex hormone), irregular ovulation, and/or multiple immature ovarian follicles — may have excess levels of estrogen that can lead to irregular uterine bleeding. (In these instances, birth control containing progestin, a synthetic progesterone, can help reverse the effects.)
Can too low or too high estrogen levels impact fertility?
Yes, and on either end of the spectrum. Estrogen is one of the hormones that keep our menstrual cycles going, so when levels are too low or too high, that can cause disruption.
In order to conceive, you need to release an egg during ovulation that’s then fertilized by sperm — cycle disruptions can make it harder to pinpoint ovulation and time sex or insemination around the days you’re most likely to get pregnant. Decreasing estrogen levels can also indicate that menopause is coming, at which point conception won’t be possible.
Are there treatments for too low or too high estrogen levels?
When low estrogen levels cause uncomfortable symptoms (like hot flashes or vaginal dryness) in postmenopausal people, a common treatment is hormone replacement therapy (HRT). Through administering systemic HRT or low-dose vaginal products, synthetic estrogen (often combined with synthetic progesterone) can improve symptoms.
“There is still a lot of hesitation in the public and among some healthcare providers about the safety of hormone replacement therapy in and around menopause and this is because of the nature in which the data were originally released back in the ‘90s,” explains Dr. Conti. “Thankfully, thorough reviews of that data have shown that for people without an increased risk of breast cancer, heart disease, stroke, or deep venous thromboembolism (DVT), hormone replacement can absolutely be safe and effective.”
Some people are more sensitive than others to the levels of synthetic estrogen in medications like HRT or hormonal birth control). If you notice unpleasant side effects, your healthcare provider may work with you to find an alternative dose or form of medication.
As for lifestyle modifications that are clinically proven to impact estrogen levels? Dr. Conti says no — aside from weight loss if a higher body-fat percentage is leading to increased estrogen. (And no, research doesn’t back up the rumor that soy intake is linked to high estrogen levels.)
Dr. Jenn Conti is an OB-GYN and serves as an adjunct clinical assistant professor at Stanford University School of Medicine.