Sex hormones in humans — Cambridge IGCSE Combined Science
The stages of the menstrual cycle and how the lining of the uterus changes over about 28 days.
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The menstrual cycle lasts about 28 days with ovulation around day 14, controlled by FSH, LH, oestrogen and progesterone. Cambridge IGCSE Biology 16.5.
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Quick check questions
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