At a Glance
What is ovulation?
Ovulation is the release of a mature egg from the ovary, the key event that makes conception possible.
When does it happen?
Typically once per cycle, around mid-cycle, but timing varies widely between women and cycles.
How long is the fertile window?
About 5 to 6 days, with the most fertile day being the day before ovulation.
Why does ovulation matter for fertility?
Without ovulation, pregnancy cannot happen. Healthy ovulation supports regular cycles, hormone balance, and good egg development.
What Is Ovulation? (Simple Explanation)
Ovulation is when one of the ovaries releases a mature egg, which then travels into the fallopian tube. This is the moment when the egg can be fertilised.
In everyday terms, ovulation is the monthly event that creates the opportunity for pregnancy.
It is the result of a carefully coordinated hormonal sequence involving:
- FSH (to grow the follicle)
- Oestrogen (to prepare the body for ovulation)
- LH (to trigger egg release)
- Progesterone (to support the second half of the cycle)
How Ovulation Works (Step-by-Step)
1. Follicles Begin Maturing (Follicular Phase)
FSH stimulates several follicles in the ovary to start maturing.
One becomes dominant; this is the egg that will (usually) be released.
2. Oestrogen Rises
As the dominant follicle grows, it produces rising levels of oestrogen, which:
- Thickens the uterine lining
- Improves cervical mucus
- Sends feedback to the brain that the egg is nearly ready
3. LH Surge
Once oestrogen peaks, the brain releases a surge of luteinising hormone (LH).
This LH surge triggers ovulation.
4. The Egg Is Released (Ovulation)
Around 24 to 36 hours after the LH surge, the mature egg is released from the ovary into the fallopian tube.
5. Progesterone Rises (Luteal Phase)
After ovulation, the empty follicle becomes the corpus luteum, which produces progesterone to support implantation.
The Fertile Window: When Pregnancy Is Most Likely
The egg survives for only 12 to 24 hours after ovulation. However, sperm can survive up to 5 days in fertile cervical mucus.
This means the fertile window is:
- About 5 to 6 days total
- With the highest chances in the 1 to 2 days before ovulation
Understanding this window — not just the day of ovulation — is key for timing intercourse or assisted conception.
Signs of Ovulation
Women may notice one or more signs:
- Egg-white cervical mucus (clear, stretchy, slippery)
- Increased libido
- Heightened energy or mood
- Mild pelvic discomfort (mittelschmerz)
- A slight temperature rise after ovulation (BBT)
Tracking these signs can help identify the fertile window.
How to Confirm Ovulation
The most reliable methods include:
- LH urine tests (predict the LH surge that precedes ovulation)
- Basal body temperature (BBT) — confirms ovulation after it occurs
- Cycle tracking apps, when used alongside physical signs
- Blood progesterone testing — confirms ovulation in the luteal phase
- Ultrasound monitoring (in clinical settings)
No single method is perfect, but combining signs increases accuracy.
Why Ovulation Matters for Fertility
Healthy ovulation impacts:
- Egg quality: the months-long development process that leads to ovulation
- Hormone balance: especially oestrogen and progesterone
- Cycle regularity
- Endometrial preparation
- Timing of intercourse or treatment
Ovulatory function is one of the most important markers of reproductive health.
Common Causes of Irregular or Absent Ovulation
Disrupted ovulation can result from:
- PCOS
- Thyroid disorders
- Poor nutritional status
- High prolactin
- Stress & cortisol imbalance
- Under-eating or excessive exercise
- Insulin resistance
- Low body fat or high body fat
- Perimenopause
- Inflammation or chronic illness
Many of these factors are modifiable and respond well to targeted support.
Why This Matters
Understanding ovulation empowers women to:
- Track their fertile window more accurately
- Recognise when ovulation may not be occurring
- Support egg health through nutrition and lifestyle
- Know when it’s time to seek medical evaluation
Ovulation is not just about fertility; it’s a vital sign of hormonal and metabolic wellbeing.
