Understanding Your Menstrual Cycle: The Four Phases Explained
Most people learn that a cycle is roughly 28 days and leave it there. Understanding what actually happens across those weeks makes it far easier to recognise what is normal for you and what is worth raising with a doctor.
Phase 1: Menstruation (Days 1 to 5, approximately)
Day one of your cycle is the first day of proper bleeding, not spotting. The uterine lining sheds because no pregnancy occurred in the previous cycle. Oestrogen and progesterone are both at their lowest, which is part of why energy often dips.
Bleeding typically lasts three to seven days. Heavy bleeding over an extended period is worth discussing with a doctor, partly because ongoing blood loss can contribute to low iron.
Phase 2: The Follicular Phase (Days 1 to 13, approximately)
This overlaps with menstruation and continues after bleeding stops. Follicles in the ovaries begin maturing, and one becomes dominant. Oestrogen rises steadily, rebuilding the uterine lining.
Many people notice energy and mood lift through this phase as oestrogen climbs.
Phase 3: Ovulation (Around Day 14)
A surge in luteinising hormone triggers the release of an egg. This is the fertile window, and the egg survives roughly 12 to 24 hours, though sperm can survive several days, which widens the window in practice.
Some people notice a change in cervical mucus, a slight temperature rise, or mild one-sided discomfort. Others notice nothing at all, which is equally normal.
Phase 4: The Luteal Phase (Days 15 to 28, approximately)
Progesterone rises to maintain the uterine lining. If no pregnancy occurs, both hormones fall and the cycle restarts. This drop is associated with the symptoms many recognise as PMS, including mood changes, bloating, breast tenderness and disrupted sleep.
What Counts as Normal
Cycle length varies considerably between individuals. Anywhere from 21 to 35 days is generally considered within range, and some variation month to month is expected. What matters more is your own pattern and whether it changes.
Worth raising with a doctor:
- Cycles consistently shorter than 21 or longer than 35 days
- Periods that stop for several months without pregnancy
- Bleeding heavy enough to disrupt daily life
- Severe pain that pain relief does not manage
- Bleeding between periods
Irregular cycles are one of the more common signs of PCOS. If that sounds familiar, our article on eating for hormonal balance may be a useful starting point, alongside a proper diagnosis.
Tracking Helps
Recording start dates, flow and symptoms over a few months gives you and your doctor far more to work with than memory alone. Patterns often become obvious on paper that are invisible day to day.
For a clear clinical overview of the cycle, the NHS guide to periods is a reliable reference.
Where Supplements Fit
Supplements do not regulate a cycle on their own, and anything persistently irregular deserves a diagnosis rather than self-treatment. Where a specific need has been identified, formulas such as Insol Sachet and DHEA D3 Tablet are used to support hormonal balance. Speak to your doctor about what is appropriate for you, or browse our Women's Health collection.
