IGCSE Biology glossary
Menstrual cycle
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A repeating cycle of approximately 28 days in which the uterus lining is prepared for possible pregnancy. It involves menstruation (shedding of the lining), repair and thickening of the lining (controlled by oestrogen), ovulation around day 14, and maintenance of the lining (controlled by progesterone).
What to include in an exam answer
Know the key events and timing: menstruation (days 1-5), uterus lining thickens (days 5-14, controlled by oestrogen), ovulation (day 14), lining maintained (days 14-28, controlled by progesterone). If no implantation, progesterone drops and the cycle restarts.
Example in context
Describe what happens during the menstrual cycle from day 1 to day 14 (3 marks): Days 1-5: the uterus lining breaks down and is lost as menstruation. Days 5-14: oestrogen from the ovaries causes the uterus lining to repair and thicken. Around day 14: a surge in oestrogen causes ovulation, where an egg is released from the ovary.
Related syllabus topic
Reproduction