What Is Estrogen? Everything You Need to Know

Estrogen is one of the primary female sex hormones, and it serves an important function in both reproductive and overall health.

Estrogen supports many important processes, from the development of secondary sex characteristics (like breast growth) to regulating your menstrual cycle. It plays an essential role in ovulation, pregnancy, and vaginal lubrication. Estrogen also has a variety of non-reproductive functions. It can impact your mood, bone health, brain function, weight, and even the condition of your skin and hair.

In this guide, we’ll walk through the different types of estrogen and how they function during key life stages like puberty, pregnancy, and menopause. You’ll learn how fluctuating and declining estrogen levels can affect how you feel, both physically and emotionally, and what symptoms to watch out for.

We’ll also cover common conditions linked to estrogen imbalance and explore treatment options like hormone replacement therapy that may help you feel more like yourself again.

There are three main types of estrogen naturally found in the body, each with its own purpose:

• Estrone (E1). This is the main form of estrogen in your body after menopause. While it’s considered a “weaker” type of estrogen, it can be converted into other forms when needed.

• Estradiol (E2). This is the most potent and prevalent form of estrogen in people of reproductive age. Both males and females produce estradiol, though it’s much more abundant in females and plays a central role in the menstrual cycle and fertility.

• Estriol (E3). The body makes this form of estrogen in large amounts during pregnancy. But outside of pregnancy, levels of estriol are typically very low.

Estrogen plays a key role in the female reproductive system, but its purpose and effects depend on your life stage. 

Estrogen During Puberty

Estrogen levels start to rise during puberty. It contributes to many of the physical and hormonal changes that support growth and development. 

These changes can include: 

• Developing breasts

• Growing pubic and underarm hair

• Starting menstruation

• Shifts in fat distribution (especially around the hips, thighs, and bottom)

Estrogen During the Menstrual Cycle

During the reproductive years, estrogen works in tandem with other hormones — especially progesterone and luteinizing hormone — to help regulate your menstrual cycle. Your levels naturally rise and fall throughout each cycle. 

During the first half of your cycle (known as the follicular phase), rising estrogen levels help thicken the uterine lining to prepare for a potential pregnancy. 

Estrogen levels peak just before ovulation, which helps trigger the release of an egg. It also helps thin the cervical mucus, making it easier for sperm to reach the egg. After ovulation, estrogen levels fall again. 

Throughout the reproductive years, estrogen also contributes to vaginal lubrication and tissue flexibility, which can make sex more comfortable.

Estrogen During Pregnancy

If conception occurs, estrogen levels rise significantly and continue to increase throughout pregnancy. Estrogen plays several vital roles in supporting pregnancy.

During pregnancy, estrogen helps: 

• Stimulate blood flow to the uterus

• Support the development of the placenta 

• Aid the growth of breast tissue in preparation for breastfeeding 

Estrogen During Perimenopause and Menopause

Menopause is a natural stage of life that marks the end of your reproductive years. By the time you reach menopause, your body will have gradually stopped producing estrogen the way it used to.  

The transition to menopause, known as perimenopause, can unfold over the course of several years. It’s common for estrogen levels to rise and fall unpredictably during this time. While menstrual cycles, ovulation, and pregnancy can still occur, estrogen levels will gradually decline. 

Once you reach menopause — officially defined as going 12 months without a menstrual period — ovulation ends and estrogen levels drop permanently. At this time, the primary form of estrogen in your body switches from estradiol (E2) to estrone (E1). 

Estrogen is a key hormone that helps support overall health. 

Estrogen plays a role in:

• Brain health and cognitive function (including your ability to concentrate)

• Bone and joint health 

• Sleep

• Heart health

• Urinary health

• Skin health (including collagen production, elasticity, and moisture retention) 

• Metabolic health (including blood sugar levels and fat distribution)

Where Is Estrogen Produced in Women?

The ovaries are the primary source of estrogen in premenopausal women, but other parts of the body also contribute to estrogen production.

Here's how different parts of the body contribute to estrogen production:

• Ovaries. During the reproductive years, the ovaries are the primary source of estrogen. 

• Adrenal glands. These small glands located above the kidneys produce androgens (another sex hormone). The body can convert androgens into estrogen, which becomes particularly important after menopause.

• Fat tissue. Fat cells also contribute to estrogen production, especially estrone, the primary form of estrogen after menopause. 

• Brain. Certain areas of the brain also produce estrogen.

Estrogen levels naturally fluctuate throughout life — even day to day — influenced by factors like age, menstrual cycle phase, and overall life stage. Because of this, what’s considered “normal” can vary quite a bit from person to person.

Because hormone levels are always changing, there is no one-and-done lab test that can give you all the answers. If you’re noticing symptoms that suggest a hormone imbalance, your healthcare provider might recommend labwork to get a clearer picture of your hormone health and guide any next steps.

Estrogen can be measured through blood tests, urine samples, and sometimes saliva tests. To account for fluctuations, these tests typically need to be repeated to see how your estrogen levels track over time. 

Estrogen is essential to many body systems, so when levels are out of balance — whether too high or too low — it can contribute to certain health conditions. In some cases, those conditions can also disrupt estrogen production. 

Here are a few conditions commonly linked to estrogen imbalances:

• Polycystic ovary syndrome (PCOS). PCOS often involves higher estrogen relative to progesterone, along with other hormone disruptions.

• Endometriosis. Estrogen can fuel the growth of endometrial tissue outside the uterus, contributing to inflammation and pain.

• Obesity. Fat tissue produces estrogen. Excess body fat may contribute to hormonal imbalances.

• Infertility. Too little or too much estrogen can interfere with ovulation and implantation. 

• Uterine fibroids. These noncancerous (benign) tumors are sensitive to estrogen and may grow in response to higher estrogen levels.

• Osteoporosis. Estrogen helps maintain bone density, so low levels can increase the risk of bone loss (particularly after menopause). 

• Anorexia nervosa. Anorexia can impact estrogen levels by disrupting the signals that regulate hormone production.

• Breast cancer. Breast cancer can grow in response to estrogen. This is known as estrogen-receptor-positive breast cancer.

• Turner syndrome. This genetic condition often results in low estrogen due to underdeveloped ovaries.

The symptoms of an estrogen imbalance can vary depending on the cause.

But generally speaking, when estrogen levels shift — especially during perimenopause — your body works hard to find a new hormonal balance. This can bring about a wide range of physical and emotional symptoms.

Common symptoms of perimenopause and menopause, and in some cases, estrogen imbalances more broadly, include:

• Hot flashes and night sweats. These sudden waves of heat and sweating are linked to hormone-related changes in blood vessel regulation.

• Sleep disturbances. Frequent nighttime wake-ups, insomnia, and daytime fatigue can all be signs of menopause. 

• Urinary and reproductive symptoms. Vaginal dryness, irritation, pain during intercourse, decreased sex drive, and increased urinary urgency can all occur during peri and postmenopause. 

• Emotional and cognitive changes. Mood swings, brain fog, anxiety, depression, and difficulty focusing can all arise with low estrogen levels. 

• Cycle changes. During perimenopause, you may experience irregular or unpredictable periods and worse premenstrual syndrome (PMS)

What Happens When You Have Low Estrogen?

Low estrogen levels can happen because of menopause, certain medical conditions, eating disorders, or after ovarian surgery.

Symptoms of low estrogen may include:

• Irregular or missed periods

• Hot flashes and night sweats

• Vaginal dryness

• Decreased libido

• Mood changes

What Happens When Estrogen Levels Are Too High?

High levels of estrogen can result from hormone therapy, certain medications, obesity (due to estrogen production in fat cells), or conditions like estrogen-producing tumors.

High estrogen levels can cause:

• Bloating or weight gain

• Breast tenderness

• Mood swings or anxiety

• Irregular periods

• Increased risk of blood clots or stroke

• Higher risk of breast cancer and endometrial cancer

There are a variety of evidence-based treatment options to help you manage estrogen-related issues. These include both hormonal and non-hormonal treatments.

Hormone Replacement Therapy

Hormone replacement therapy (HRT) is one of the most effective ways to ease perimenopause and menopause symptoms like hot flashes, night sweats, vaginal dryness, and mood changes. It works by supplementing the estrogen and progesterone your body is no longer producing.

Most women using HRT will take a combination of estrogen and progestin (a synthetic form of progesterone). Progestin helps balance out supplemental estrogen, which taken on it’s own, can put you at risk of uterine cancer. If you’ve had a hysterectomy, your doctor may recommend estrogen-only therapy. 

HRT comes in several forms, including: 

• Pills

• Skin patches

• Gels

• Creams

• Vaginal rings 

Research shows that starting HRT within 10 years of menopause (or before age 60) may lower your risk of heart disease, osteoporosis, and other chronic conditions. But there are risks involved. There are ways to mitigate these risks, such as using low-dose therapy or localized treatment that doesn’t reach your bloodstream. 

Potential risks associated with some forms of HRT include:

• Stroke

• Blood clots

• Uterine cancer

• Breast cancer

It’s always best to weigh the risks and benefits with your doctor before starting treatment.

Birth Control Pills 

Birth control pills, patches, and rings that contain estrogen and progestin (combined hormonal contraceptives) are another form of hormone therapy available to women in perimenopause. This form of therapy may help with certain perimenopause symptoms, such as irregular periods and hormone-related headaches. 

Contraceptives have the added benefit of preventing unplanned pregnancy during perimenopause.

Hormone-Free Treatments

If HRT isn’t the right path for you, there are other ways to manage symptoms without using hormones. These include:

• Antidepressants. SSRIs or SNRIs may help treat depression, support mood stability, and ease hot flashes. 

• Gabapentin. Originally developed as an antiseizure medication, gabapentin can also help manage hot flashes. 

• Clonidine. This blood pressure medication may reduce hot flashes

• Fezolinetant. This non-hormonal drug was recently approved by the FDA to specifically treat moderate to severe hot flashes.

• Oxybutynin. This medication is often prescribed for an overactive bladder, but may also treat hot flashes

• Ospemifene. This selective estrogen receptor modulator (SERM) can treat painful sex caused by the thinning of vaginal tissues. 

• Vaginal lubricants. These can help relieve dryness and discomfort. Choose fragrance-free, gentle options to minimize irritation.

Lifestyle Changes to Maintain Healthy Estrogen Levels

Daily habits play a huge role in how you feel. Whether you’re navigating perimenopause or dealing with another condition, these changes can make a meaningful difference:

• Stay active. Regular movement supports bone and muscle health, boosts mood, and promotes restful sleep. Aim for at least 150 minutes of cardio each week, and a few strength training sessions.

• Fuel your body. Incorporate foods rich in phytoestrogens, like soy, flaxseed, and legumes (think tempeh and tofu). These plant compounds may mimic estrogen and help ease hot flashes.

• Prioritize sleep hygiene. Keep a consistent sleep schedule, reduce screen time before bed, and create a cool, quiet sleeping space to support deeper rest.

• Manage stress. Chronic stress can worsen hormone-related symptoms. Mindfulness practices like meditation, yoga, deep breathing, or walks in nature can help. If symptoms persist, talk therapy may be worth exploring.

• Explore complementary therapies. Some people find relief through acupuncture or herbal remedies like black cohosh. Talk to your provider before starting any new supplements, especially if you take other medications.

• Estrogen influences your whole body and mind. It affects mood, cognition, bone health, sleep quality, libido, and even skin and hair health.

• Estrogen levels naturally change throughout different life stages. Estrogen surges during puberty and pregnancy and gradually declines leading up to menopause.

• You deserve care that honors your unique experience. Treatment options are available to support your needs and help you thrive physically and emotionally. 

If something feels off, you’re not alone. Reach out to a healthcare provider who listens and supports you — your experience is valid, and there are many ways to find relief and balance.