The Female Hormonal Cycle
At a Glance
What is the female hormonal cycle?
A recurring rhythm of hormonal changes that prepare the body for ovulation and (potential) pregnancy.
Which hormones are involved?
FSH, LH, oestrogen, progesterone, and several supporting hormones including AMH, insulin, and thyroid hormones. These hormones work together to regulate ovulation, cycle timing, and uterine readiness.
How long is a typical cycle?
Around 24 to 35 days, with ovulation occurring roughly mid-cycle.
Why does it matter for fertility?
Healthy ovulation and balanced hormones are essential for egg development, egg release, conception, and implantation.
What Is the Female Hormonal Cycle?
The female hormonal cycle is a coordinated sequence of hormonal rises and falls that repeat each month. These hormonal shifts:
- Mature an egg
- Trigger ovulation
- Prepare the uterus for implantation
- And allows the cycle to reset if pregnancy doesn’t occur
The cycle has four phases, each with a distinct hormonal pattern and purpose.
The Four Phases of the Cycle
Please keep in mind, cycle lengths and hormone patterns vary from person to person. These timeframes are averages, not rules.
1. Menstrual Phase (Days 1–5, approx.)
What happens:
Menstruation is a sign that the body is responding to hormonal signals and beginning a new cycle. The uterine lining sheds, marking the start of a new cycle.
Hormones:
- Hormone levels are at their lowest.
- FSH gently begins to rise to recruit new follicles.
Why it matters for fertility:
This is a “reset” phase. Healthy shedding prepares the uterus for a new cycle and future implantation.
2. Follicular Phase (Days 1–14, overlaps with menstruation early on)
What happens:
FSH stimulates several small follicles (each containing an immature egg).
One becomes dominant and continues to mature.
Key hormones:
- FSH: Helps follicles grow.
- Oestrogen: Rises steadily, thickening the uterine lining and preparing the body for ovulation.
Why it matters:
Healthy follicular development is essential for producing a high-quality egg.
Oestrogen also plays a major role in cervical mucus quality, making it easier for sperm to reach the egg.
3. Ovulation (Mid-cycle, usually around Day 12–16)
What happens:
A sharp LH surge triggers the dominant follicle to release a mature egg.
Key hormones:
- LH: The “ovulation trigger.”
- Oestrogen: Peaks just before ovulation.
Why it matters:
Ovulation is the core of the fertility cycle. Without ovulation, pregnancy cannot occur.
Signs of ovulation may include:
- Stretchy, egg-white cervical mucus
- A sensation of increased libido or energy
- A slight temperature rise (after ovulation)
The fertile window includes the days leading up to ovulation, as sperm can survive for several days.
4. Luteal Phase (After ovulation until the next period)
What happens:
The empty follicle transforms into the corpus luteum, which produces progesterone.
Key hormones:
- Progesterone: Rises sharply.
- Oestrogen: Remains moderate.
Why it matters:
Progesterone stabilises and nourishes the uterine lining.
This phase typically lasts around 12–14 days to support successful implantation.
If pregnancy does not occur, progesterone falls and the next period begins.
The Key Hormones Explained Simply
FSH (Follicle-Stimulating Hormone)
Helps follicles grow and supports early egg development.
LH (Luteinising Hormone)
Triggers ovulation, the release of the mature egg.
Oestrogen
Builds the uterine lining, supports cervical mucus, boosts libido, and helps select a healthy egg.
Progesterone
Essential after ovulation.
It stabilises the lining and prepares it for implantation.
Other hormones with major influence:
- Thyroid hormones: regulate metabolism and ovulation.
- Insulin: high levels can disrupt ovulation (especially in PCOS).
- AMH: reflects ovarian reserve (how many follicles remain).
- Prolactin: high levels can suppress ovulation.
- Cortisol: the primary stress hormone. Chronically elevated cortisol can interfere with ovulation and progesterone production.
When these hormones work in balance, the cycle unfolds predictably and efficiently.
Why Understanding the Cycle Matters
A healthy hormonal cycle is essential for:
- Predictable ovulation
- Good cervical mucus quality
- Healthy egg development
- Proper progesterone production
- Successful implantation
Small imbalances, even ones women may not notice, can impact fertility. The good news?
Most cycle and hormonal issues respond very well to targeted nutrition, stress support, and medical guidance where needed. Understanding your cycle gives you valuable insight into your overall health, not just fertility.
