Oestrogen and progesterone in control of the menstrual cycle - Higher

Several hormones are involved in the menstrual cycle of a woman:

  • Follicle stimulating hormone (FSH) causes the maturation of an egg in a follicle in the ovary.
  • Luteinising hormone (LH) stimulates the release of the egg (ovulation).
  • Oestrogen secreted by the follicle as it matures. It is involved in repairing and thickening the uterus lining.
  • Progesterone is produced by the empty egg follicle after the egg is released to maintain the lining. If a woman is pregnant, progesterone levels stay high and she doesn't have periods. If she is not pregnant, then the levels of progesterone drop and she will have a period.

The menstrual cycles last for approximately 28 days, and graphs can be used to follow changes to the hormones during this process.

A diagram representing the menstrual cycle and hormone levels
Question

Explain the difference between the amount of oestrogen and progesterone in the bloodstream at days 14 and 21.

Day 14 - There is more oestrogen than progesterone as oestrogen is produced by the developing egg follicle up to ovulation when the egg is released.

Day 21 - There is now more progesterone than oestrogen, as it is produced by the empty egg follicle after the egg is released to maintain the uterus lining in case of pregnancy.