The menstrual cycle and pregnancy

Question 1

What happens during days 1-5?

Answer 1

• FSH and LH levels are high
• On egg becomes the ‘dominant’ one
• FSH and LH stimulate the build up of the follicle, which then releases oestrogen
• Uterus lining breaks down if fertilisation didn’t occur

Question 2

What happens during days 5-12?

Answer 2

• Follicle continues to grow and produce more oestrogen
• Oestrogen reduces FSH secretion
• Oestrogen causes the uterus lining to thicken

Question 3

What happens during days 12-15?

Answer 3

• Very high oestrogen levels produces a surge in LH and FSH
• High levels of LH causes the follicle to burst and an egg is released
• The follicle reforms to form a ‘corpus lute’ which secretes high levels of progesterone and medium levels of oestrogen

Question 4

What happens during days 15-28?

Answer 4

• High levels of progesterone inhibit the production of LH and FSH
• As a result, the corpus lute slowly degrades
• In turn, levels of progesterone and oestrogen slowly fall and are low by day 28
• The uterus lining is maintained due to progesterone and oestrogen