Female sex hormones: What they do and why balance matters

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Your hormones are some of the most important regulators in your body, playing an integral role in your overall health and supporting numerous physiological processes. Females have a distinct hormonal profile, which controls everything from ovulation and menstruation right through to pregnancy and menopause.

Here’s what you should know about the female sex hormones, how they can shift over time and when it might be worth seeing a doctor about a hormonal change.

Note: In this article, sex is used as a biological classification, meaning female assigned at birth.

Types of female sex hormones

Females have a range of hormones, but the main female sex hormones are:

• Oestrogen, which is largely produced in the ovaries as well as in fat cells and your adrenal glands. Oestrogen plays a role in regulating the menstrual cycle, sustaining pregnancy, helping to preserve bone strength and keeping cholesterol levels in check
• Progesterone, which is made by the ovaries after you ovulate and by your placenta during pregnancy. Progesterone plays a key part in supporting pregnancy, preparing the uterus for implantation and maintaining the uterine lining

The female body also makes the sex hormone testosterone, albeit in much smaller amounts. It’s created in the ovaries and adrenal glands and promotes sexual desire.

And while not sex hormones specifically, your body also makes certain hormones that support your reproductive system. These include human chorionic gonadotropin (hCG), prolactin, luteinising hormone (LH) and follicle-stimulating hormone (FSH) – we’ll explore these in more detail below.

The role your reproductive hormones play over time

While you always have certain hormones in your body, their levels and roles change drastically throughout your life, even starting in the womb.

In-utero and birth

Both oestrogen and progesterone are secreted by your mother’s womb to support reproductive development and help grow organs like your uterus and fallopian tubes. Another hormone, known as Anti-Müllerian Hormone (AMH), is also produced in the womb to make male reproductive structures disappear.

After you’re born, oestrogen and progesterone levels fall rapidly and remain fairly low throughout childhood.

Puberty

Sometime between the ages of 8 and 13, the majority of females hit puberty [1] – a time of drastic changes to hormones and reproductive and sexual development.

Your brain secretes something called gonadotropin-releasing hormone (GnRH), which triggers the production of luteinising hormone (LH) and follicle-stimulating hormone (FSH) in your pituitary gland (a pea-sized gland located below your brain). Your ovaries then start making a significantly higher amount of oestrogen, driving key changes such as:

• Breast development, starting with breast buds
• Maturation of your ovaries and uterus
• An increase and redistribution of body fat, particularly around the hips and thighs
• Pubic and armpit hair growth
• A growth spurt and widening of the hips
• Eventually, the first menstruation

Menstruation

Menstruation usually starts around 2-3 years after the breast buds form [2] – these are the first stage of breast development. Early periods are typically irregular and don’t release any eggs (a process known as anovulation), but over time, the menstrual cycle becomes more regular. The average 28-day cycle looks something like this:

• Menstrual phase (days 1-5): When you menstruate, both oestrogen and progesterone are low, allowing your uterus to shed last month’s lining and expel blood and tissue from your body as a period
• Follicular phase (days 1-13): This phase overlaps with the menstrual phase because your cycle starts on the first day of bleeding. Once last month’s period leaves your body, your uterus starts rebuilding the lining. Your brain releases FSH, oestrogen gradually rises, and your ovaries mature follicles containing eggs. In short, your body is preparing for a possible pregnancy
• Ovulatory phase (around day 14, but can be earlier or later): During ovulation, your LH level surges. This prompts the release of an egg from your ovaries. The egg travels down your fallopian tubes to your uterus and waits up to 24 hours for potential fertilisation from sperm
• Luteal phase (days 15-28): In the luteal phase, your ovaries produce progesterone to support a possible pregnancy. If you’re pregnant, progesterone remains high. If you’re not, progesterone and oestrogen decrease and the menstrual cycle resets

Sex drive

Female libido is mostly driven by testosterone, which peaks just before ovulation. The purpose is to encourage sexual activity to result in a pregnancy. During this phase, you may notice that you’re more interested in sex than usual.

Oestrogen and progesterone affect sexual desire, too. The former helps to increase blood flow and vaginal lubrication and also peaks before ovulation, while the latter has a calming effect and peaks just after ovulation. Higher progesterone levels bring your libido down to baseline, as there’s less need to conceive once you’ve already ovulated.

Pregnancy

If you become pregnant, your menstrual cycle stops, and your hormones adjust to accommodate your growing baby. Pregnancy has different phases, which include:

• Conception and implantation (1-2 weeks after ovulation): If the egg is fertilised, it implants in the uterus. The embryo then starts secreting hCG, preventing your uterus from shedding its lining. Fun fact: hCG is the hormone detected in pregnancy tests!
• First trimester: hCG keeps rising alongside oestrogen. Progesterone levels steadily rise during the first few weeks of pregnancy, thickening the cervix and forming the mucus plug. These rapid hormonal shifts are the main reason you experience early pregnancy symptoms like nausea, sore breasts and fatigue. At the end of the first trimester, your placenta takes over and becomes the main producer of hormones. Oestrogen and progesterone continue to rise, but hCG levels fall
• Second and third trimesters: In the mid to late stages of pregnancy, oestrogen and progesterone sustain fetal growth. Your body also produces relaxin – a hormone that relaxes blood vessels to ensure adequate blood gets to the baby and loosens ligaments and joints in preparation for birth – and prolactin, which supports milk production in the breasts
• Childbirth: When your body is ready to give birth, oestrogen and progesterone levels adjust to initiate labour. You also make oxytocin to trigger contractions and prostaglandins (hormone-like compounds) to soften your cervix, making vaginal delivery easier

Postpartum

When you give birth, your hormone levels decrease suddenly – namely, oestrogen and progesterone. The immediate drop encourages enhanced milk production, but it can also cause significant emotional shifts. For some women, this materialises as the “baby blues” (a brief period of low mood), while for others it can cause postpartum depression – a much more serious mental health condition that requires treatment.

If you’re breastfeeding, your oestrogen levels typically remain low to prevent ovulation. Some women rely on this as a form of contraception, but it’s not foolproof – pregnancy can and does still happen.

After several months, hormone levels return to baseline, and most women find their period comes back.

Perimenopause and menopause

Perimenopause and menopause cause the menstrual cycle to eventually stop.

Perimenopause usually starts between ages 45 and 55 (but can be earlier or later)[3] and lasts several years. During this phase, oestrogen hormones fluctuate wildly, progesterone levels decline, and ovulation becomes irregular. Libido changes, mood swings and hot flushes are also common symptoms during perimenopause, largely due to the hormonal fluctuations that are going on.

Menopause is defined as going 12 consecutive months without a period [3]. Both oestrogen and progesterone levels stay low, which can result in changes to bone density and cardiovascular health [4][5].

For this reason, some postmenopausal women choose to undergo hormone replacement therapy (HRT) to replace lost oestrogen. Hormone therapy is used to alleviate menopause symptoms such as hot flashes and mood swings. It can be administered in various forms, including oral tablets, topical gels and skin patches.

There are potential risks associated with HRT, including an increased risk of blood clots, stroke and certain types of cancer [6]. While the risk is low, non-hormonal options are also available for managing menopausal symptoms.

When hormones become unbalanced

Your hormones are supposed to shift over time, but there are some scenarios where an imbalance of sex hormones can signal an underlying condition. These include:

• Polycystic ovary syndrome (PCOS): PCOS involves high levels of androgens like testosterone. This can cause symptoms such as irregular periods, weight changes and excess hair
• Early menopause: In some cases, the ovaries stop working before 40, much earlier than the typical age of menopause. This is a condition known as premature ovarian insufficiency
• Chronic stress: Chronic stress can lead to increased cortisol production, which can interfere with the menstrual cycle
• Eating disorders: Conditions like anorexia and bulimia can disrupt hormones and affect the menstrual cycle
• Miscarriage: Pregnancy loss can cause key pregnancy hormones to drop rapidly
• Cancer (or cancer treatment): Some cancers and cancer treatments can impact sex hormone levels, including breast cancer [7]
• Side effects: Hormonal imbalances can also be a side effect of certain medications.

Common signs of hormone imbalance

Symptoms can vary from person to person. However, an imbalance of sex hormones can trigger the following symptoms:

Menstrual and reproductive signs

• Irregular periods
• Very heavy or very light bleeding
• Severe PMS
• Spotting between periods
• Difficulty conceiving
• Loss of libido
• Vaginal dryness or discomfort

Mood, brain and sleep

• Mood swings
• Anxiety or increased irritability
• Low mood or depression
• Brain fog or poor concentration
• Poor sleep or early waking
• Reduced stress tolerance

Energy, weight and metabolism

• Persistent fatigue
• Unexplained weight gain or difficulty losing weight
• Increased abdominal fat
• Blood sugar swings or strong cravings
• Reduced muscle mass

Skin, hair and physical changes

• Acne, especially jawline or adult acne
• Thinning hair or hair loss
• Excess facial or body hair
• Dry skin
• Brittle nails
• Breast tenderness or swelling

Temperature and physical sensations

• Hot flushes or night sweats
• Cold sensitivity
• Headaches or migraines
• Joint aches or stiffness

Other possible signs

• Bloating or fluid retention
• Changes in body odour
• Worsening allergies
• Digestive changes
• Decreased bone density over time

When to see a doctor

If you’re experiencing any of the above, it’s always a good idea to book a chat with your GP or gynaecologist. They can assess your symptoms and figure out what might be causing them – be it a hormonal imbalance or something else entirely.

And even if you’re not showing signs of a hormonal imbalance, it’s important to see a doctor or gynaecologist at least once a year for an overall health check. It’s a great opportunity to have your hormones looked at to make sure everything’s working as it should.

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