What Your Period Blood Is Telling You: Colour, Flow, and What Changes Mean

Your period is not just a monthly inconvenience. It is a monthly report card — a direct reflection of your hormonal health over the preceding cycle. The colour, texture, timing, and volume of your flow all carry information. Most women are never taught to read it. Once you can, it becomes one of the most useful pieces of monthly data available.

What Healthy Period Blood Looks Like

A healthy period is bright to medium red — not too dark, not pink — flowing smoothly for 3–6 days without significant clotting. Volume is moderate: enough to require changing protection every 3–4 hours on heavier days, not so much that you are soaking through hourly or passing large clots.

Some variation from day to day is normal — lighter at the start and end, heavier in the middle. Some variation month to month is also normal. What matters is your baseline and when it changes.

Reading the Colour

Bright red

Healthy. Fresh blood clearing efficiently. A bright red flow that arrives on time and moves at a moderate pace is a good sign of healthy uterine circulation and hormone balance.

Dark red or maroon

Blood that has taken longer to leave the uterus. Some dark blood at the start or end of your period is normal — this is older blood from the edges of the shedding lining. Predominantly dark or maroon blood throughout suggests slower uterine clearance, often linked to oestrogen dominance, poor circulation, or progesterone insufficiency.

Brown or black

Very old blood — from the previous cycle that wasn't fully cleared, or spotting before the true period begins. Brown spotting in the days before your period is a classic sign of low progesterone and a shortened luteal phase — the progesterone drop is happening earlier than it should, causing the lining to begin shedding before true menstruation.

Pink or very light

Low oestrogen — the lining is thin. Common in perimenopause, in athletes with low body fat, in women under-eating, or with hypothalamic amenorrhoea. Pale pink blood with light flow suggests the oestrogen support for lining development is insufficient.

Orange

May indicate infection — particularly when accompanied by unusual smell. Orange-tinged discharge warrants assessment.

Reading the Texture and Flow

Clots

Small clots (smaller than a 10 cent coin) are normal — they are pieces of the uterine lining shed in larger portions. Larger clots, or passing many clots, suggests heavy flow driven by high oestrogen or low progesterone. The uterine lining has built up more than it should, and the body is clearing it less efficiently than it should.

Very heavy flow

Soaking through a pad or tampon every 1–2 hours, or passing large clots, is not normal — it warrants investigation. Causes include oestrogen dominance (the lining has built up excessively), fibroids, adenomyosis, thyroid imbalance, or bleeding disorders. Many women are told heavy periods are normal and manage them with the pill for years without the underlying cause being identified.

Very light flow

A period that lasts only 1–2 days with minimal flow suggests insufficient oestrogen to build the uterine lining adequately, or the lining is being suppressed (as with the pill or IUD). In spontaneous cycles, very light periods are often accompanied by perimenopause, significant undereating, or high levels of athletic stress.

Stringy or membrane-like tissue

The uterine lining sheds in pieces. Larger pieces or membrane-like tissue are more common with heavier flows. If you are passing what appears to be a cast of the uterine cavity — a decidual cast — this is worth discussing with a doctor.

What Changes Month to Month Mean

A single different period is not necessarily meaningful — stress, illness, travel, and significant dietary changes all affect the cycle. Two or three consecutive cycles with a consistent change are worth paying attention to.

• Cycles getting shorter — often a progesterone story; an early sign of perimenopause in women over 38
• Flow getting heavier over several months — often oestrogen dominance increasing; worth investigating for fibroids or adenomyosis if significant
• Increasing brown spotting before the period — shortened luteal phase, low progesterone
• Flow getting lighter in perimenopause — normal as oestrogen production becomes more variable

Frequently Asked Questions

Are period clots normal?

Small clots are normal. Clots larger than a 50 cent coin, or passing many clots throughout your period, is not — it suggests heavy flow driven by oestrogen dominance, fibroids, or adenomyosis, and warrants investigation.

What does brown discharge before my period mean?

Brown spotting in the days before your period typically indicates a shortened luteal phase — progesterone is dropping earlier than it should. This is a reliable sign of low progesterone and is one of the earlier indicators of perimenopause or stress-driven progesterone depletion.

Why is my period suddenly lighter?

Lighter periods can result from hormonal contraception thinning the lining, perimenopause reducing oestrogen, significant stress or undereating suppressing the HPO axis, or thyroid imbalance. Consistently lighter periods over several months warrant investigation if the change is significant.