Why do we bleed on periods?

Menstruation, or having a period, is a natural process that happens as part of the female reproductive cycle. But one common question many women and girls ask is: Why do we actually bleed on our periods? Let’s break it down simply.

1. The Monthly Cycle of Preparation

Every month, the body prepares for a possible pregnancy. Hormones like estrogen and progesterone work together to thicken the lining of the uterus (called the endometrium) so it can support a fertilized egg.

If pregnancy doesn’t happen, the body no longer needs this thick lining.

2. Hormone Drop = Bleeding Starts

When no egg is fertilized, levels of estrogen and progesterone drop sharply. This sudden change signals the uterus to shed its lining.

That shedding comes out of the body through the vagina in the form of:

  • Blood

  • Tissue from the uterine lining

  • Mucus

This is what we see as period blood.

3. Why Periods Come With Cramps

As the uterus contracts to push out its lining, many women feel cramps or pain in the lower abdomen or back. These contractions help the blood and tissue flow out of the body.

4. How Much Blood Is Normal?

  • On average, women lose about 30–80 ml of blood (roughly 2–6 tablespoons) per cycle.

  • The bleeding usually lasts between 3 to 7 days.

If bleeding is very heavy (soaking through pads/tampons every hour), it’s best to check with a doctor.

5. How to Keep Periods Healthy

  • Eat iron-rich foods (like spinach, beans, or red meat) to replace lost iron.

  • Stay hydrated and active to reduce cramps.

  • Track your cycle to understand your flow and patterns.

  • Use safe menstrual products like pads, tampons, menstrual cups, or period underwear depending on comfort.

✨ In short: We bleed on periods because the uterus sheds its lining when pregnancy does not occur. It’s the body’s natural way of resetting for the next cycle.

Back to blog