WOMEN'S HEALTH
Words Worth Knowing
Plain language explanations of the terms that come up most often when navigating perimenopause and menopause. No jargon. No assumptions about prior knowledge.
The Hormones
Estrogen
The primary female sex hormone. Often talked about as if it is a single thing, but estrogen is actually a group of related hormones, the main ones being estradiol, estrone and estriol. Estradiol is the most active form during the reproductive years and the one that declines most significantly during perimenopause and menopause. Estrogen does far more than regulate the reproductive cycle. It protects bone density, supports brain function, regulates mood, maintains cardiovascular health, keeps skin and tissue elastic and plays a role in dozens of other processes throughout the body. Because estrogen receptors exist in virtually every organ system, its decline during menopause is felt widely and sometimes in surprising ways.
The primary female sex hormone. Often talked about as if it is a single thing, but estrogen is actually a group of related hormones, the main ones being estradiol, estrone and estriol. Estradiol is the most active form during the reproductive years and the one that declines most significantly during perimenopause and menopause. Estrogen does far more than regulate the reproductive cycle. It protects bone density, supports brain function, regulates mood, maintains cardiovascular health, keeps skin and tissue elastic and plays a role in dozens of other processes throughout the body. Because estrogen receptors exist in virtually every organ system, its decline during menopause is felt widely and sometimes in surprising ways.
Progesterone
A hormone produced mainly by the ovaries after ovulation each month. In the reproductive years, progesterone rises in the second half of the menstrual cycle to prepare the uterine lining for a potential pregnancy. If no pregnancy occurs, levels drop and the lining is shed. Progesterone has a calming effect on the nervous system and plays a role in mood, sleep and anxiety. When it declines during perimenopause, many women notice increased anxiety, sleep disruption and mood changes, sometimes before any other symptoms appear. In hormone therapy, progesterone is given alongside estrogen to protect the uterine lining. Women who no longer have a uterus do not need to take progesterone.
A hormone produced mainly by the ovaries after ovulation each month. In the reproductive years, progesterone rises in the second half of the menstrual cycle to prepare the uterine lining for a potential pregnancy. If no pregnancy occurs, levels drop and the lining is shed. Progesterone has a calming effect on the nervous system and plays a role in mood, sleep and anxiety. When it declines during perimenopause, many women notice increased anxiety, sleep disruption and mood changes, sometimes before any other symptoms appear. In hormone therapy, progesterone is given alongside estrogen to protect the uterine lining. Women who no longer have a uterus do not need to take progesterone.
Testosterone
Often thought of as a male hormone, but women produce testosterone too, primarily in the ovaries and adrenal glands. In fact when all hormone levels are converted to the same units, women actually have more testosterone in their bodies than estrogen. Testosterone in women supports libido, energy levels, muscle mass, bone density, mood and cognitive function. Its decline during perimenopause and menopause can contribute to loss of libido, fatigue, difficulty building or maintaining muscle and changes in mental sharpness. Testosterone therapy for women is available, though it is not yet FDA approved for this purpose and must usually be prescribed through a compounding pharmacy or specialist.
Often thought of as a male hormone, but women produce testosterone too, primarily in the ovaries and adrenal glands. In fact when all hormone levels are converted to the same units, women actually have more testosterone in their bodies than estrogen. Testosterone in women supports libido, energy levels, muscle mass, bone density, mood and cognitive function. Its decline during perimenopause and menopause can contribute to loss of libido, fatigue, difficulty building or maintaining muscle and changes in mental sharpness. Testosterone therapy for women is available, though it is not yet FDA approved for this purpose and must usually be prescribed through a compounding pharmacy or specialist.
FSH (Follicle Stimulating Hormone)
A hormone produced by the pituitary gland that signals the ovaries to prepare an egg for release each month. As the ovaries become less responsive during perimenopause, the pituitary gland produces more and more FSH in an attempt to stimulate them. High FSH levels on a blood test can be one indicator that a woman is approaching menopause, though because levels fluctuate so much during perimenopause a single reading is not a reliable diagnostic tool.
A hormone produced by the pituitary gland that signals the ovaries to prepare an egg for release each month. As the ovaries become less responsive during perimenopause, the pituitary gland produces more and more FSH in an attempt to stimulate them. High FSH levels on a blood test can be one indicator that a woman is approaching menopause, though because levels fluctuate so much during perimenopause a single reading is not a reliable diagnostic tool.
Cortisol
The body's primary stress hormone, produced by the adrenal glands. Cortisol follows a natural daily rhythm, rising in the morning to help wake the body and falling through the day. During perimenopause, this rhythm can become disrupted, contributing to the pattern many women notice of waking between 2am and 4am with a racing mind. Elevated cortisol also increases insulin resistance and can worsen the weight changes many women experience around this time. Stress reduction, regular sleep routines and avoiding caffeine in the afternoon can help support a healthier cortisol rhythm.
The body's primary stress hormone, produced by the adrenal glands. Cortisol follows a natural daily rhythm, rising in the morning to help wake the body and falling through the day. During perimenopause, this rhythm can become disrupted, contributing to the pattern many women notice of waking between 2am and 4am with a racing mind. Elevated cortisol also increases insulin resistance and can worsen the weight changes many women experience around this time. Stress reduction, regular sleep routines and avoiding caffeine in the afternoon can help support a healthier cortisol rhythm.
The Stages
Perimenopause
The transition phase before menopause. It begins when the ovaries start producing less estrogen and progesterone, causing hormone levels to fluctuate unpredictably rather than following their usual monthly pattern. Perimenopause can begin as early as the mid-thirties, though it more commonly starts in the early to mid-forties. It typically lasts between two and eight years, with four years being average. This is often when the most disruptive symptoms are felt, precisely because hormones are swinging rather than simply declining steadily. Many women do not realise they are in perimenopause because the blood tests their doctor orders often come back within normal ranges, even though they are experiencing significant symptoms.
The transition phase before menopause. It begins when the ovaries start producing less estrogen and progesterone, causing hormone levels to fluctuate unpredictably rather than following their usual monthly pattern. Perimenopause can begin as early as the mid-thirties, though it more commonly starts in the early to mid-forties. It typically lasts between two and eight years, with four years being average. This is often when the most disruptive symptoms are felt, precisely because hormones are swinging rather than simply declining steadily. Many women do not realise they are in perimenopause because the blood tests their doctor orders often come back within normal ranges, even though they are experiencing significant symptoms.
Menopause
A single point in time, not a phase. Menopause is defined as one year after the last menstrual period. The average age in the UK and US is 51, though anything from 45 to 55 is considered within the normal range. For women who have had a hysterectomy or use a hormonal IUD, periods may have stopped for other reasons, in which case blood tests measuring FSH levels can help confirm where they are in the transition. Menopause itself is not the most symptomatic phase for many women. The most turbulent period is often perimenopause in the years leading up to it.
A single point in time, not a phase. Menopause is defined as one year after the last menstrual period. The average age in the UK and US is 51, though anything from 45 to 55 is considered within the normal range. For women who have had a hysterectomy or use a hormonal IUD, periods may have stopped for other reasons, in which case blood tests measuring FSH levels can help confirm where they are in the transition. Menopause itself is not the most symptomatic phase for many women. The most turbulent period is often perimenopause in the years leading up to it.
Postmenopause
Everything after menopause, lasting for the rest of a woman's life. Some symptoms like hot flashes and night sweats may ease in the years following menopause, but other effects of estrogen decline, particularly on bone density, cardiovascular health and vaginal and urinary tissue, continue and can progress without treatment. This is why the decision about hormone therapy is not only relevant at the moment of menopause but continues to matter throughout postmenopause.
Everything after menopause, lasting for the rest of a woman's life. Some symptoms like hot flashes and night sweats may ease in the years following menopause, but other effects of estrogen decline, particularly on bone density, cardiovascular health and vaginal and urinary tissue, continue and can progress without treatment. This is why the decision about hormone therapy is not only relevant at the moment of menopause but continues to matter throughout postmenopause.
Premature Ovarian Insufficiency (POI)
When the ovaries stop functioning normally before the age of 40. Approximately 1% of women experience this. It can be caused by genetic factors, autoimmune conditions or medical treatments such as chemotherapy or radiotherapy. POI is different from early menopause in that the ovaries may still produce some estrogen intermittently and pregnancy can occasionally still occur. Women with POI have a longer period of estrogen deficiency than women who reach menopause at the average age, which increases their long-term health risks. Hormone therapy is particularly important for this group.
When the ovaries stop functioning normally before the age of 40. Approximately 1% of women experience this. It can be caused by genetic factors, autoimmune conditions or medical treatments such as chemotherapy or radiotherapy. POI is different from early menopause in that the ovaries may still produce some estrogen intermittently and pregnancy can occasionally still occur. Women with POI have a longer period of estrogen deficiency than women who reach menopause at the average age, which increases their long-term health risks. Hormone therapy is particularly important for this group.
Early Menopause
Menopause that occurs between the ages of 40 and 45. Approximately 5% of women experience early menopause. It can happen naturally or as a result of surgery, chemotherapy or radiotherapy. Women who reach menopause early have a longer period of estrogen deficiency than average and an increased risk of osteoporosis and cardiovascular disease as a result. Specialist advice is particularly important for this group.
Menopause that occurs between the ages of 40 and 45. Approximately 5% of women experience early menopause. It can happen naturally or as a result of surgery, chemotherapy or radiotherapy. Women who reach menopause early have a longer period of estrogen deficiency than average and an increased risk of osteoporosis and cardiovascular disease as a result. Specialist advice is particularly important for this group.
Treatments and Therapies
HRT (Hormone Replacement Therapy)
Also called MHT (menopausal hormone therapy). Treatment that replaces the estrogen and, where needed, progesterone that the body is no longer producing in the same quantities. HRT relieves menopause symptoms and, when started early in perimenopause or within the first 10 years of menopause, has been shown to reduce the risk of cardiovascular disease, osteoporosis, diabetes and dementia. It comes in several forms including patches, gels, sprays, tablets and vaginal preparations. The fears around HRT that arose from a 2002 study have since been largely dismantled. Modern HRT uses bioidentical hormones and the risk profile is very different from the synthetic hormones used in that study. For most women under 60 or within 10 years of menopause, the benefits of HRT outweigh the risks.
Also called MHT (menopausal hormone therapy). Treatment that replaces the estrogen and, where needed, progesterone that the body is no longer producing in the same quantities. HRT relieves menopause symptoms and, when started early in perimenopause or within the first 10 years of menopause, has been shown to reduce the risk of cardiovascular disease, osteoporosis, diabetes and dementia. It comes in several forms including patches, gels, sprays, tablets and vaginal preparations. The fears around HRT that arose from a 2002 study have since been largely dismantled. Modern HRT uses bioidentical hormones and the risk profile is very different from the synthetic hormones used in that study. For most women under 60 or within 10 years of menopause, the benefits of HRT outweigh the risks.
Bioidentical Hormones
Hormones that are structurally identical to those produced naturally by the body. Modern HRT products use bioidentical estradiol and progesterone, meaning the body recognises and processes them the same way it would its own hormones. This is different from the conjugated equine estrogen (derived from horse urine) and synthetic progestin used in the 2002 Women's Health Initiative study. When people talk about bioidentical hormones in the context of modern HRT, they are referring to licensed, regulated pharmaceutical products. There is a separate category of compounded bioidentical hormones made by compounding pharmacies to individual specifications, which are not regulated in the same way and have less evidence behind them.
Hormones that are structurally identical to those produced naturally by the body. Modern HRT products use bioidentical estradiol and progesterone, meaning the body recognises and processes them the same way it would its own hormones. This is different from the conjugated equine estrogen (derived from horse urine) and synthetic progestin used in the 2002 Women's Health Initiative study. When people talk about bioidentical hormones in the context of modern HRT, they are referring to licensed, regulated pharmaceutical products. There is a separate category of compounded bioidentical hormones made by compounding pharmacies to individual specifications, which are not regulated in the same way and have less evidence behind them.
Vaginal Estrogen
A localised form of estrogen applied directly to the vaginal area, available as a cream, pessary, ring or tablet. It treats the genital and urinary symptoms of menopause, including vaginal dryness, discomfort during sex and recurrent urinary tract infections, without significantly raising estrogen levels in the bloodstream. It is considered safe for virtually all women, including those with a history of breast cancer. Vaginal estrogen does not require progesterone alongside it. It is one of the most effective and underused treatments available for these symptoms.
A localised form of estrogen applied directly to the vaginal area, available as a cream, pessary, ring or tablet. It treats the genital and urinary symptoms of menopause, including vaginal dryness, discomfort during sex and recurrent urinary tract infections, without significantly raising estrogen levels in the bloodstream. It is considered safe for virtually all women, including those with a history of breast cancer. Vaginal estrogen does not require progesterone alongside it. It is one of the most effective and underused treatments available for these symptoms.
CBT (Cognitive Behavioural Therapy) for Menopause
A structured talking therapy that has good evidence for reducing the impact of hot flashes, sleep disruption, anxiety and low mood associated with menopause. It does not change hormone levels but changes the way the brain and body respond to symptoms, reducing their perceived severity and impact. It is recommended in NICE guidelines as an effective non-hormonal option for women who cannot or choose not to take HRT.
A structured talking therapy that has good evidence for reducing the impact of hot flashes, sleep disruption, anxiety and low mood associated with menopause. It does not change hormone levels but changes the way the brain and body respond to symptoms, reducing their perceived severity and impact. It is recommended in NICE guidelines as an effective non-hormonal option for women who cannot or choose not to take HRT.
Other Useful Terms
Vasomotor Symptoms
The medical term for hot flashes and night sweats. They are caused by the hypothalamus, the part of the brain that acts as the body's thermostat, becoming hypersensitive to small changes in body temperature as estrogen levels decline. The hypothalamus responds by triggering a rapid cooling response, which is experienced as a sudden wave of heat, flushing and sometimes sweating. Experienced by around 75 to 80% of women going through menopause.
The medical term for hot flashes and night sweats. They are caused by the hypothalamus, the part of the brain that acts as the body's thermostat, becoming hypersensitive to small changes in body temperature as estrogen levels decline. The hypothalamus responds by triggering a rapid cooling response, which is experienced as a sudden wave of heat, flushing and sometimes sweating. Experienced by around 75 to 80% of women going through menopause.
Genitourinary Syndrome of Menopause (GSM)
The collective term for the changes that occur in the vagina, vulva and urinary tract as a result of declining estrogen. Symptoms include vaginal dryness, itching, discomfort or pain during sex, urinary urgency, frequency and recurrent UTIs. Unlike hot flashes, which tend to ease over time, GSM typically worsens without treatment. Affects over 50% of postmenopausal women. Highly treatable with vaginal estrogen.
The collective term for the changes that occur in the vagina, vulva and urinary tract as a result of declining estrogen. Symptoms include vaginal dryness, itching, discomfort or pain during sex, urinary urgency, frequency and recurrent UTIs. Unlike hot flashes, which tend to ease over time, GSM typically worsens without treatment. Affects over 50% of postmenopausal women. Highly treatable with vaginal estrogen.
Endocrine Disruptors
Chemicals that interfere with the body's hormonal system. They can mimic hormones, block them or alter the way they are produced, broken down or responded to by cells. Common endocrine disruptors include PFAS (found in non-stick cookware and food packaging), phthalates (found in plastics and fragranced products), BPA and related compounds (found in food containers and receipts) and certain pesticides including atrazine. Research suggests that exposure to these chemicals during perimenopause may affect how women experience the transition, since they interact with the same hormonal systems already under pressure from declining estrogen. Reducing exposure where possible is a practical step that supports hormonal health at every life stage.
Chemicals that interfere with the body's hormonal system. They can mimic hormones, block them or alter the way they are produced, broken down or responded to by cells. Common endocrine disruptors include PFAS (found in non-stick cookware and food packaging), phthalates (found in plastics and fragranced products), BPA and related compounds (found in food containers and receipts) and certain pesticides including atrazine. Research suggests that exposure to these chemicals during perimenopause may affect how women experience the transition, since they interact with the same hormonal systems already under pressure from declining estrogen. Reducing exposure where possible is a practical step that supports hormonal health at every life stage.
Osteoporosis
A condition in which bones lose density and become fragile and more likely to fracture. Estrogen plays a key role in maintaining bone density throughout a woman's life. When it declines at menopause, bone loss accelerates significantly. Women reach peak bone density at around age 35 and the rate of loss increases sharply in the years around menopause. 50% of women will experience an osteoporotic fracture in their lifetime. Strength training, adequate calcium, vitamin D and magnesium, and where appropriate hormone therapy, can all significantly reduce risk.
A condition in which bones lose density and become fragile and more likely to fracture. Estrogen plays a key role in maintaining bone density throughout a woman's life. When it declines at menopause, bone loss accelerates significantly. Women reach peak bone density at around age 35 and the rate of loss increases sharply in the years around menopause. 50% of women will experience an osteoporotic fracture in their lifetime. Strength training, adequate calcium, vitamin D and magnesium, and where appropriate hormone therapy, can all significantly reduce risk.
Sarcopenia
The age-related loss of muscle mass and strength. Menopause significantly accelerates sarcopenia because both estrogen and testosterone play important roles in maintaining muscle tissue. In the first 10 years of menopause, women can lose 10 to 15% of their muscle mass. This matters not only for strength and physical function but also because muscle mass is directly linked to insulin sensitivity, bone health and long-term metabolic health. Resistance training and adequate protein intake are the most effective interventions.
The age-related loss of muscle mass and strength. Menopause significantly accelerates sarcopenia because both estrogen and testosterone play important roles in maintaining muscle tissue. In the first 10 years of menopause, women can lose 10 to 15% of their muscle mass. This matters not only for strength and physical function but also because muscle mass is directly linked to insulin sensitivity, bone health and long-term metabolic health. Resistance training and adequate protein intake are the most effective interventions.
Insulin Resistance
A condition in which cells become less responsive to insulin, the hormone that allows glucose to enter cells for energy. Estrogen helps regulate insulin sensitivity, so its decline during menopause can cause insulin resistance to increase. This is one reason why many women notice changes in weight, particularly around the midsection, and in their blood sugar levels during perimenopause even when their diet and activity have not changed. Reducing added sugar, increasing fiber and protein, strength training and maintaining a healthy sleep pattern all help manage insulin resistance.
A condition in which cells become less responsive to insulin, the hormone that allows glucose to enter cells for energy. Estrogen helps regulate insulin sensitivity, so its decline during menopause can cause insulin resistance to increase. This is one reason why many women notice changes in weight, particularly around the midsection, and in their blood sugar levels during perimenopause even when their diet and activity have not changed. Reducing added sugar, increasing fiber and protein, strength training and maintaining a healthy sleep pattern all help manage insulin resistance.
Women's Health Initiative (WHI)
A large US study begun in the 1990s and stopped early in 2002 after preliminary results suggested a slightly increased risk of breast cancer in women taking combined estrogen and synthetic progestin. The announcement caused a global wave of fear around HRT and a dramatic drop in prescriptions that persisted for over two decades. The study has since been extensively reanalysed. Its results were reported in a misleading way, the study population was not representative of women who would typically be starting HRT, and the formulations used were not the bioidentical hormones prescribed today. The estrogen-only arm of the same study actually showed a reduction in breast cancer risk. In November 2025 the US FDA began removing outdated safety warnings from most HRT products, acknowledging the prior guidance was based on misinterpreted data.
A large US study begun in the 1990s and stopped early in 2002 after preliminary results suggested a slightly increased risk of breast cancer in women taking combined estrogen and synthetic progestin. The announcement caused a global wave of fear around HRT and a dramatic drop in prescriptions that persisted for over two decades. The study has since been extensively reanalysed. Its results were reported in a misleading way, the study population was not representative of women who would typically be starting HRT, and the formulations used were not the bioidentical hormones prescribed today. The estrogen-only arm of the same study actually showed a reduction in breast cancer risk. In November 2025 the US FDA began removing outdated safety warnings from most HRT products, acknowledging the prior guidance was based on misinterpreted data.
Knowledge is not just useful here. It is the thing that changes conversations with doctors, that helps you advocate for yourself, that makes the difference between leaving an appointment with answers and leaving with more questions. You deserve to understand what is happening in your own body.
The more you know, the more you can ask for.
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