The menstrual cycle and pregnancy hormonesSpec B14.2.4
In short
The menstrual cycle lasts about 28 days with ovulation around day 14, controlled by FSH, LH, oestrogen and progesterone. Cambridge IGCSE Biology 16.5.
The menstrual cycle is a series of changes in the ovaries and in the lining of the uterus. It repeats about every 28 days.
| Stage | Days | Change in the ovary and the uterus lining |
|---|---|---|
| Menstruation | 1 to 5 | The lining of the uterus breaks down and is lost through the vagina with blood |
| Repair | 5 to 14 | An egg cell matures in an ovary. The uterus lining is repaired and thickens |
| Ovulation | Around 14 | An egg cell is released from an ovary into the oviduct |
| Maintenance | 14 to 28 | The lining stays thick, ready for an embryo. If there is no pregnancy, the lining breaks down and the cycle starts again |
(opens full size in a new tab)Quick check
What happens to the uterus lining during menstruation?
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It breaks down and is lost through the vagina with blood.
About how long is one menstrual cycle?
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About 28 days.
What happens to the uterus lining after menstruation?
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It is repaired and thickens, ready for a fertilised egg.
Written and checked against the Cambridge IGCSE Combined Science (0653) specification · Updated October 2026