A Complete Timeline of Women’s Hormones

And so it begins. Puberty can start anytime between 8-14, and actually starts in the brain. The body begins to release GnRH in stronger, more regular pulses, which triggers the release of FSH and LH, which then wake up the ovaries. 

The ovaries start producing oestradiol, which drives breast development, widens the hips, manages fat redistribution and growth spurts, and eventually the closure of the growth plates. 

Fun fact: Girls tend to stop growing soon after their first period. 

A menstrual cycle can take a few years to stabilise, hence why many of us may have experienced erratic periods at the start of puberty. Once they do calm, a standard cycle is around 28 days, but anything from 21 to 35 days is also normal. 

A textbook cycle looks like this: 

• Menstrual Phase: One to five days 

The menstrual phase is seen as ‘day one’ of a completely new cycle. Women bleed as the body sheds the lining of the uterine, and this is also when oestrogen and progesterone drop to their lower levels, and we feel like we need more rest and care. That’s completely normal! 

• Follicular Phase: End of period to day 14

During the follicular phase, the brain signals the ovaries to mature an egg in the follicle. FSH begins to rise to stimulate the follicle, which then causes oestrogen levels to steadily climb and thicken the uterine lining. Energy levels usually start to increase, and moods are often stable.  

• Ovulation Phase: Around day 14 

Around the mid-point of a cycle, ovulation begins with a sharp surge in hormones that triggers the release of the mature egg into the fallopian tube. This is a peak time for oestrogen, which triggers a massive spike in LH and a smaller peak in FSH, causing ovulation. 

• Luteal Phase: Days 15 to 28

In the luteal phase, the empty follicle becomes the corpus luteum, which causes a rise in progesterone and makes the lining receptive to an embryo. If there is no pregnancy, the corpus luteum breaks down after about 12 - 14 days. Oestrogen and progesterone fall, the lining sheds, and the cycle starts again.

And it’s that hormone drop in the days before a period that we can thank for PMS.

The early 20s are the biological peak in fertility, and usually the time when many women start taking contraception such as the pill. Many contraceptives work by overriding the hormones produced throughout a standard cycle, but this depends on the types of contraception used. 

The combined pill, for example, supplies synthetic oestrogen plus a progestogen to suppress GnRH, FSH, and LH, so no follicle matures, and no ovulation happens. The progestogen-only pill (mini pill) stops ovulation altogether. 

After stopping contraception, the natural cycle usually returns within a few weeks to months. If an egg is fertilised, the embryo implants itself around 6 - 10 days after ovulation and starts making hCG, the hormone pregnancy tests detect. hCG's key job is to ‘rescue’ the corpus luteum so it keeps producing progesterone instead of breaking down, which prevents a period.

Now, pregnancy. A woman’s body becomes a serious hormone during this time. hCG rises rapidly during the first couple of weeks (roughly doubling every two to three days) and peaks around 8 - 11 weeks pregnant. That’s usually when nausea and morning sickness enter the chat. 

At the same time, the brand new organ that the body grows, the placenta, takes over progesterone production from the corpus luteum. After that, oestrogen and progesterone climb to levels higher than anything seen in a normal cycle. Progesterone gets to work relaxing the smooth muscle, keeping the womb calm, and slowing digestion (causing heartburn and constipation too), while oestrogen supports blood flow and growth of the womb and breasts.

Honourable mentions also go to the human placental lactogen, which makes the mother more insulin-resistant to divert glucose to the baby (which can cause gestational diabetes), and relaxin, which loosens ligaments ready for birth (and contributes to pelvic girdle pain). Prolactin rises to prepare the breasts for milk, but high progesterone blocks full milk production until after delivery. 

We told you, pregnancy turns a woman’s body into a hormone cocktail, and we still manage to get through our daily lives.

If pregnancy turns a woman’s body into a hormone haven, once the baby is born, our bodies experience a serious hormone drop. We’re talking dramatic. Once the placenta is delivered, oestrogen and progesterone fall from their pregnancy highs to below normal pre-pregnancy levels within just a few days. A few days!! 

It’s that progesterone drop that lets prolactin do its job, so milk ‘comes in’ around days 2–5. But it’s also that same crash that is linked to the ‘baby blues’ and can contribute to postnatal depression. 

If breastfeeding occurs, the high prolactin suppresses GnRH, which keeps oestrogen low and usually delays periods. Oxytocin also works to trigger the milk let-down reflex and supports bonding. 

If not breastfeeding, periods usually return within about 6–8 weeks, and ovulation can happen before the first period, so contraception matters sooner than many expect.

Perimenopause is the next big hormonal shift in a woman’s life, and usually starts in the mid-40s but can happen from the late 30s too. It lasts for around four years, but again, it can be longer in some cases. And the cause? As the remaining follicles run low, the ovaries produce less inhibin B and AMH, so the brain pushes harder with more FSH.

The key thing to remember is that perimenopause is not a smooth decline, but an erratic swing. Our old friend oestrogen can spike higher than normal in some cycles and crash in others, while more cycles are anovulatory, so progesterone is often low. 

It’s this hormone rollercoaster that explains perimenopause symptoms like irregular and sometimes heavier periods, hot flushes and night sweats, poor sleep, anxiety, low mood, irritability, brain fog, and worsening PMS. Sorry, girls, it’s tough.

And to add insult to injury, pregnancy is still possible during this time.

Menopause is a single point in time: 12 consecutive months without a period. Once a woman reaches this point (usually around the age of 50), they can officially wear the badge of ‘survived menopause’. 

Finally, post-menopause and the after-effects of 40 years of hormone shifts. Let’s get into it. 

Now that the ovaries have stopped producing oestradiol and progesterone. FSH and LH stay permanently high because there's no feedback to turn them down. The main oestrogen now is oestrone, a weaker form made in fat tissue. 

The long-term effects of low oestrogen include faster bone density loss, rising cardiovascular risk, and persisting menopause symptoms such as vaginal dryness, discomfort and recurrent urinary infections, which tend to worsen rather than resolve. 

And that, ladies, is a (sadly brief) but complete timeline of women’s hormones. You’re all heroes! 

GnRH (gonadotropin-releasing hormone): The boss in the brain. It tells the pituitary gland to release FSH and LH. When it starts pulsing properly, puberty begins.

FSH (follicle-stimulating hormone): Released by the pituitary, it tells the ovaries to grow follicles, the little sacs that hold eggs. It rises in perimenopause as the brain works harder to get a response from the ovaries.

LH (luteinising hormone): A sudden LH surge mid-cycle triggers ovulation, and it's what ovulation tests detect.

Oestrogen (oestradiol and oestrone): Oestradiol, made mainly by the ovaries, drives breast development, builds up the womb lining each month, and supports bones, heart, skin and mood. After menopause, the milder oestrone, made in fat tissue, becomes the main type.

Progesterone: Made after ovulation by the corpus luteum (and later by the placenta), it prepares the womb lining for a pregnancy and keeps it stable. When it drops, your period starts.

Androgens (including testosterone and DHEA): Made by the ovaries and adrenal glands, they cause body hair, oily skin and spots in puberty, and contribute to libido and energy throughout life.

hCG (human chorionic gonadotropin): Made by the embryo after implantation, it tells the body to keep producing progesterone so no period arrives. It's what pregnancy tests pick up, and it's linked to early pregnancy nausea.

hPL (human placental lactogen): Made by the placenta, it makes the mother's body more resistant to insulin so more glucose reaches the baby. It's why gestational diabetes can happen.

Relaxin: Softens ligaments and joints, especially around the pelvis, to make room for birth.

Prolactin: Rises during pregnancy to prepare the breasts and kicks milk production into gear after birth. When high during breastfeeding, it also tends to pause periods.

Oxytocin: Powers contractions during birth, triggers milk let-down during breastfeeding, and plays a part in bonding.