Your cycle is a monthly health report. Most women never read it.

Dr. Emmanuel L. Yanthan, MS (OB-GYN) Obstetrician & Gynecologist · Updated August 2026

Most women can tell me roughly when their last period was. Very few can tell me how long their cycles run, how many days they bleed, or how heavy the heaviest day is. That is a shame, because those numbers are a monthly readout on your thyroid, your iron stores, your hormones and whether you are ovulating at all.

The four numbers worth knowing

• Cycle length — first day of bleeding to the day before the next starts. Anywhere from 21 to 35 days is normal. It is the consistency that matters more than the number.
• Days of bleeding — usually three to seven.
• Heaviest day — how many pads or tampons, and whether you had to change at night.
• Pain — and specifically whether it stops you working or studying.

What the cycle is actually doing

Four phases, running one into the next:

Menstruation. The lining of the uterus sheds. Three to seven days.

Follicular phase. An egg matures in the ovary while the lining rebuilds.

Ovulation. The egg is released — around the middle of the cycle, though “day 14” is an average, not a rule. This is the fertile window.

Luteal phase. The lining thickens ready for a pregnancy. If none happens, it sheds, and the next cycle begins.

This matters practically: if your cycles are wildly unpredictable, ovulation probably is too — which is why irregular periods and difficulty conceiving so often turn up together.

What a changed pattern is telling you

A cycle that has changed character is worth more attention than a cycle that has always been unusual for you.

• Cycles stretching past 35 days, or fewer than eight periods a year — often points to inconsistent ovulation, commonly PCOS or a thyroid problem.
• Bleeding much heavier than it used to be — fibroids, adenomyosis, a polyp, or an underactive thyroid.
• Bleeding between periods or after sex — always worth examining.
• Exhaustion that arrives with heavy periods — iron deficiency, which is extremely common and very treatable.

One thing to stop doing

Stop treating period pain that stops your day as something to be endured. Pain severe enough to keep you home from work or college is not a low pain threshold and it is not a personality trait. It is a symptom, and it often has a findable cause.

Start tonight

Open the notes app on your phone. Write today’s date and whether you are bleeding. Do that daily for two cycles and you will walk into a consultation with better information than most patients ever bring.

General information, not advice about your particular situation. No article can replace being examined. Evita GyneCare provides antenatal care, gynecological consultations and outpatient diagnostics; we do not provide childbirth or caesarean section services.