Several hormones are involved in the menstrual cycle of a woman:
The menstrual cycles last for approximately 28 days, and graphs can be used to follow changes to the hormones during this process.
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.