The menstrual cycleSpec 7.4
In short
The menstrual cycle is a series of changes in a woman that repeats about every 28 days. The uterus lining breaks down in menstruation (days 1 to 5), is repaired and thickens, an egg is released at ovulation around day 14, and the lining is then maintained. Oestrogen repairs the lining and progesterone maintains it.
The menstrual cycle is a series of changes in a woman that repeats about every 28 days. Each cycle, an egg is released from an ovary and the lining of the uterus is prepared in case the egg is fertilised.
| Stage | Days | What happens |
|---|---|---|
| Menstruation | 1 to 5 | The lining of the uterus breaks down and is lost through the vagina with blood |
| Repair | 5 to 14 | The uterus lining is repaired and thickens again |
| Ovulation | Around 14 | An egg is released from an ovary |
| Maintenance | 14 to 28 | The lining stays thick, ready for a fertilised egg. If there is no pregnancy it breaks down and the cycle starts again |
The roles of two hormones
- Oestrogen is made in the ovaries. It causes the repair and growth of the uterus lining.
- Progesterone is made in the ovaries. It maintains the uterus lining.
When you read a hormone graph, say which day the change happens on and whether the level rises, falls or peaks. Use figures from the axes.
(opens full size in a new tab)Written and checked against the Edexcel GCSE Combined Science (1SC0) specification · Updated October 2026