Female Sex Hormones: Functions, Life Stages, and Imbalance
Female sex hormones are chemical messengers that guide many of the body’s most important changes: puberty, menstrual cycles, pregnancy, and eventually menopause. The primary female sex hormones are estrogen, progesterone, and small but important amounts of testosterone. These hormones don’t just affect reproduction. They also influence bone health, mood, sexual function, skin, metabolism, and even cardiovascular risk.
Hormone levels naturally rise and fall across the lifespan. Big shifts often happen during puberty, the luteal phase of the menstrual cycle, pregnancy and postpartum, and perimenopause/menopause. When these shifts are within the expected range, the body adapts. When they’re too high, too low, or poorly timed, they can contribute to symptoms like irregular periods, low libido, acne, hot flashes, or mood changes. That’s why understanding female sex hormones is essential for clinicians, patients, and anyone building women’s health content.
What Are Female Sex Hormones?
Female sex hormones are endocrine chemicals produced mainly by the ovaries and, to a lesser extent, the adrenal glands (and the placenta during pregnancy). Once released into the bloodstream, these hormones act as messengers that tell organs and tissues how to function at a given time. Their primary job is to support reproductive health, but they also regulate areas people don’t always connect to hormones, such as bone density, skin health, mood, metabolism, and sexual desire.
The three most important sex hormones in people assigned female at birth are:
Estrogen – the main hormone responsible for female sexual development, menstrual cycle regulation, and protecting the cardiovascular and skeletal systems.
Progesterone – prepares the uterine lining for pregnancy, supports early pregnancy, and helps stabilize menstrual cycles.
Testosterone (in smaller amounts) – supports libido, muscle and bone maintenance, and red blood cell production.
These hormones don’t work in isolation. They respond to signals from the hypothalamus and pituitary gland in the brain (via LH and FSH), creating a hormone axis that rises and falls in predictable patterns across the month and across life stages. When this axis is disrupted, symptoms of hormonal imbalance can appear.
Types of Female Sex Hormones
Female physiology relies on a small group of sex hormones that work together and change in a cyclical pattern. The three core hormones are estrogen, progesterone, and testosterone (in lower amounts). Each has a distinct role, and shifts in the balance between them are often what cause symptoms patients report in clinic.
Estrogen
Estrogen is the primary female sex hormone. It is mainly produced in the ovaries, with smaller amounts from the adrenal glands and fat tissue. Estrogen helps:
Develop secondary sex characteristics during puberty
Regulate the menstrual cycle
Support vaginal and urinary tract health
Protect bones and support cardiovascular health
Estrogen levels rise in the follicular phase of the menstrual cycle, peak around ovulation, and decline before menstruation. Low estrogen over time (as in menopause) can contribute to hot flashes, vaginal dryness, and bone loss.
Progesterone
Progesterone is produced by the corpus luteum in the ovary after ovulation, and by the placenta during pregnancy. Its main job is to prepare and stabilize the uterine lining so that a fertilized egg can implant. Progesterone also:
Balances estrogen’s growth effects on the uterus
Supports early pregnancy
May influence mood, sleep, and appetite
When progesterone is low or ovulation does not occur, people may experience irregular periods, spotting, or difficulty conceiving.
Testosterone (in Lower Amounts)
Although often labeled a “male” hormone, testosterone is also made in small amounts in people assigned female at birth, mainly by the ovaries and adrenal glands. In females, testosterone helps:
Support sexual desire
Maintain muscle and bone mass
Assist in red blood cell production
Too little testosterone may contribute to low libido or fatigue, while too much (as in PCOS) can lead to acne, excess hair growth, or irregular periods.
Hormone Changes Across Life Stages (Puberty to Menopause)
Female sex hormones do not stay at one level throughout life. They follow predictable patterns driven by signals from the brain (hypothalamus and pituitary) and the ovaries. The biggest shifts happen at puberty, during the reproductive years (menstrual cycling and pregnancy), and during the menopause transition.
Puberty
Puberty usually begins when the brain increases production of FSH (follicle-stimulating hormone) and LH (luteinizing hormone). These signals tell the ovaries to start producing estrogen.
Estrogen drives breast development and growth of the uterus and vagina.
Pubic and underarm hair appear as androgens increase.
After enough cycles of hormonal signaling, ovulation starts and menstruation (menarche) follows.
This stage establishes the hormone rhythm that will continue through the reproductive years.
Menstrual Cycle and Reproductive Years
During the reproductive years, hormones follow a monthly cycle:
Follicular phase: Estrogen rises to help a follicle mature.
Ovulation: A surge of LH triggers the egg’s release.
Luteal phase: Progesterone rises to support a possible pregnancy.
If pregnancy does not occur, estrogen and progesterone drop, and menstruation begins. Any disruption to ovulation (stress, low body weight, thyroid issues, PCOS) can alter this pattern.
Pregnancy and Postpartum
During pregnancy, the placenta becomes a major hormone-producing organ.
Progesterone and estrogen stay high to support the pregnancy.
hCG supports early pregnancy.
These high levels often cause breast changes, nausea, and fatigue.
After birth, hormone levels fall quickly. Breastfeeding can keep estrogen levels lower and may temporarily suppress ovulation.
Perimenopause and Menopause
Perimenopause is the transition period before menopause when the ovaries become less responsive.
Estrogen becomes erratic, sometimes high, sometimes low.
Progesterone often declines first because ovulation becomes less frequent.
Symptoms can include hot flashes, sleep changes, mood shifts, and irregular bleeding.
Menopause is confirmed after 12 months without a period. After menopause, estrogen and progesterone stay at low but steady levels. Lower estrogen can affect bone density, vaginal tissue, and cardiovascular risk.
Common Causes of Female Hormonal Imbalance
Hormone levels naturally rise and fall, but when the change is too large, too frequent, or out of sync with the menstrual cycle, it can lead to symptoms. In females, hormonal imbalance usually means that estrogen, progesterone, and/or androgens (like testosterone) are not in the right proportions for that life stage. Below are some of the most common, clinically recognized causes.
1. Polycystic Ovary Syndrome (PCOS)
PCOS is one of the leading causes of irregular periods and ovulatory dysfunction. It is often associated with:
Higher androgen (testosterone) levels
Infrequent or absent ovulation
Insulin resistance and weight gain in some patients
Because ovulation is disrupted, progesterone may stay low, while estrogen and androgens fluctuate, creating an imbalance that shows up as acne, excess hair growth, and irregular cycles.
2. Perimenopause and Ovarian Aging
As the ovaries become less responsive (typically in the 40s), ovulation becomes less predictable. This often leads to:
Lower or inconsistent progesterone
Estrogen that swings from high to low
Irregular or heavy bleeding
This is a normal transition, but the symptoms can feel like “hormone imbalance.”
3. Primary Ovarian Insufficiency (POI)
In POI, the ovaries stop functioning normally before age 40. Estrogen levels can be low, periods can become infrequent, and fertility is affected. This is different from perimenopause because it happens earlier than expected and may need medical evaluation.
4. Thyroid Disorders
Both hypothyroidism and hyperthyroidism can interfere with menstrual regularity because thyroid hormones interact with the reproductive axis. Women with thyroid issues may report:
Irregular or heavy periods
Difficulty conceiving
Fatigue, weight changes, or mood shifts
5. Stress, Under-Eating, and Overtraining
The brain prioritizes survival over reproduction. Chronic stress, very low-calorie diets, or intense exercise can lower GnRH → LH/FSH → estrogen/progesterone, leading to missed or delayed periods (hypothalamic amenorrhea).
6. Excess Body Weight and Insulin Resistance
Adipose (fat) tissue can produce estrogen. In some women, higher body fat plus insulin resistance can worsen estrogen–androgen imbalance and aggravate PCOS-like symptoms.
7. Medications and Hormonal Contraceptives
Birth control pills, hormonal IUDs, implants, and hormone therapies alter the natural estrogen–progesterone rhythm on purpose. For most patients this is safe, but stopping or changing methods may cause temporary irregular cycles.
Symptoms of Female Hormonal Imbalance
Hormone levels naturally fluctuate across the month and with age. It becomes a concern when symptoms are persistent, worsening, or not aligned with the person’s current life stage (for example, heavy bleeding after menopause, or no periods in someone who is not pregnant). Below are common, patient-facing symptoms linked to estrogen, progesterone, and androgen (testosterone) imbalance.
1. Menstrual and Bleeding Changes
Irregular periods (shorter than 24 days or longer than 38 days)
Missed periods or very light periods
Very heavy periods or flooding
Spotting between periods
Periods that become painful after being previously mild
These often happen when ovulation is inconsistent (PCOS, perimenopause, stress-related amenorrhea).
2. Skin and Hair Changes
Adult acne or cystic breakouts, especially on jawline/chin
Oily skin
Excess hair growth on the face, chest, or abdomen (hirsutism)
Thinning hair on the scalp
These are often linked with higher androgens or insulin resistance, as in PCOS.
3. Vaginal and Sexual Symptoms
Vaginal dryness or discomfort
Lower sexual desire
Painful intercourse (often due to low estrogen or menopause)
Reduced natural lubrication
These can occur with low estrogen (menopause, postpartum, lactation) or with certain hormonal contraceptives.
4. Mood, Sleep, and Cognitive Changes
Irritability, low mood, or feeling “on edge”
PMS/PMDD-like symptoms that are getting worse
Sleep difficulty, especially around the late luteal phase
Brain fog or poor concentration
These are sometimes related to rapid shifts in estrogen and progesterone rather than absolute low levels.
5. Systemic or Metabolic Signs
Unexplained weight gain or central weight gain
Fatigue and low energy
Hot flashes or night sweats (can occur in perimenopause, thyroid issues, or from certain medications)
Headaches or migraines related to cycle timing
6. Fertility-Related Symptoms
Difficulty getting pregnant
Short luteal phase (often due to low progesterone)
Recurrent very early losses (needs medical evaluation)
Important: These symptoms are non-specific. Many can overlap with thyroid disease, anemia, chronic stress, depression, or gynecologic conditions. That’s why persistent or severe symptoms should be evaluated by a clinician.
When to See a Doctor About Hormone Changes
Not every symptom means something is “wrong” with your hormones. Puberty, postpartum, breastfeeding, perimenopause, and even short-term stress can cause temporary shifts. You should see a healthcare professional when symptoms are persistent, out of pattern, or severe, or when bleeding occurs at an unexpected time.
Red-flag symptoms (see a doctor promptly)
Vaginal bleeding after menopause (after 12 months with no period)
Very heavy bleeding (soaking through a pad/tampon every 1–2 hours, or passing large clots)
Bleeding between periods or after sex
Sudden onset of excess facial/body hair or deepening voice
Pelvic pain with fever, dizziness, or fainting
Nipple discharge (not breastfeeding)
These may signal something more than a simple hormone fluctuation and should be evaluated.
Situations that warrant evaluation
Periods suddenly become very irregular or stop for 3+ months and you are not pregnant
You are trying to get pregnant but cycles are very long, very short, or unpredictable
PMS/PMDD symptoms are affecting work, relationships, or sleep
You have recurrent miscarriages or known ovarian issues
You have symptoms of thyroid disease (cold intolerance, hair loss, constipation, anxiety, palpitations)
What a clinician may do
A provider may:
Take a full menstrual and medical history
Do a pelvic exam if bleeding or pain is present
Order blood tests (FSH, LH, estradiol, progesterone, TSH, prolactin, androgens, plus metabolic labs)
Order imaging (pelvic ultrasound) if structural causes are suspected
How Hormonal Imbalance Is Diagnosed
Diagnosing a hormonal imbalance starts with a detailed history (cycle length, bleeding pattern, pregnancies, medications, weight changes, stress) and a physical exam. From there, a clinician may order targeted tests, often timed to the menstrual cycle.
Common labs:
FSH, LH, estradiol (to assess ovarian function)
Progesterone (often mid-luteal to confirm ovulation)
TSH and sometimes prolactin (to rule out thyroid/pituitary causes)
Total/free testosterone, DHEA-S (if androgen excess is suspected)
Fasting glucose, insulin, or lipid panel (if PCOS or metabolic issues are suspected)
Imaging:
Pelvic ultrasound to look at the ovaries, uterus, endometrium, and to check for PCOS features or structural causes of bleeding.
Diagnosis is based on the pattern of findings, not one lab alone.
Treatment and Management Options
Treatment depends on the underlying cause, the person’s age, and whether they are trying to conceive.
Common approaches:
Cycle regulation: hormonal contraception or cyclic progesterone to manage heavy/irregular periods.
Treat the driver: thyroid medication for hypothyroidism, metformin or weight management for PCOS/insulin resistance.
Symptom relief: vaginal estrogen for atrophy, nonhormonal options for hot flashes (as guided by a clinician).
Lifestyle support: healthy weight range, strength training, good sleep, and stress reduction can improve hormone sensitivity.
Hormone therapy should always be clinician-guided, especially in perimenopause/menopause or when there are cardiovascular or cancer risk factors.
Summary / When to Talk to Your Provider
Female sex hormones naturally change from puberty through menopause. That is normal. It becomes a concern when bleeding is heavy or irregular, symptoms affect daily life, or changes appear at the “wrong” time (for example, bleeding after menopause or rapid hair growth).
See a healthcare professional if you notice:
Periods that suddenly change pattern
Bleeding after menopause
Signs of high androgens (acne, excess hair, scalp thinning)
Trouble getting pregnant
Systemic symptoms like fatigue, weight gain, or hot flashes that don’t match your age
References
Rosner J, Samardzic T, Sarao MS. Physiology, Female Reproduction. [Updated 2024 Mar 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537132/
Shukla A, Rasquin LI, Anastasopoulou C. Polycystic Ovarian Syndrome. [Updated 2025 Jul 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459251/
Peacock K, Carlson K, Ketvertis KM. Menopause. [Updated 2023 Dec 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507826/
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