B1: The Menstrual Cycle and Controlling Fertility

Question 1

What is the menstrual cycle?

Answer 1

The monthly release of an egg from a woman’s ovaries and the build up and breakdown of the protective lining in the uterus.

Question 2

What happens during stage 1 of the cycle?

Answer 2

• This is when the bleeding starts.

- The uterus lining breaks down for about four days.

Question 3

What happens during stage 2 of the cycle?

Answer 3

• The lining of the uterus builds up again, from day 4 to day 14, into thick spongy layer full of blood vessels, ready to receive the fertilised egg.

Question 4

What happens during stage 3 of the cycle?

Answer 4

• An egg is developed and then released from the ovary at day 14.

Question 5

What happens during stage 4 of the cycle?

Answer 5

• The wall is then maintained for about 14 days, until day 28.
• If no fertilised egg has landed on the uterus wall by day 28, the spongy lining starts to break down again and the whole cycle starts again.

Question 6

What is the menstrual cycle controlled by?

Answer 6

Hormones.

Question 7

What are the three main hormones involved in the cycle?

Answer 7

1. FSH (Follicle-Stimulating Hormone)
2. Oestrogen
3. LH (Luteinising Hormone)

Question 8

What is the role of FSH in the cycle?

Answer 8

1. It causes an egg to mature in the ovaries.

2. It stimulates that ovaries to produce oestrogen.

Question 9

Where is FSH produced?

Answer 9

By the pituitary gland.

Question 10

What is the role of oestrogen in the cycle?

Answer 10

1. It causes the pituitary gland to produce LH

2. It inhibits the further release of FSH

Question 11

Where is oestrogen produced?

Answer 11

In the ovaries.

Question 12

What is the role of LH in the cycle?

Answer 12

1. It stimulates the release of an egg at around the middle of the menstrual cycle.

Question 13

Where is LH produced?

Answer 13

By the pituitary gland.

Question 14

Why is oestrogen used as a method of contraception?

Answer 14

• Because it can be used to prevent the release of an egg.

- If oestrogen is taken everyday to keep the level of it permanently high, it inhibits the production of FSH

Question 15

What other hormones can be used to reduce fertility?

Answer 15

Progesterone.

Question 16

What are the advantages of the contraceptive pill?

Answer 16

1. It is over 99% effective at preventing pregnancy

2. It reduces the risk of getting some types of cancer

Question 17

What are the disadvantages of the contraceptive pill?

Answer 17

1. It is not 100% effective at preventing pregnancy
2. It can cause side-effects like headaches, nausea, fluid retention and irregular menstrual bleeding
3. It does not protect against STDs/STIs

Question 18

What were the side-effects of the old contraceptive pill?

Answer 18

There were concerns about a link between oestrogen and side effects like blood clots.

Question 19

What does the contraceptive pill contain?

Answer 19

Progesterone and low doses of oestrogen.

Question 20

How can hormones be used to increase fertility?

Answer 20

1. Some women have levels of FSH that are to low to cause eggs to mature. This means that no eggs are released and the woman cannot get pregnant.
2. FSH and LH can be injected into these women to stimulate egg release in their ovaries.

Question 21

What are the advantages and disadvantages of injecting LH and FSH to increase fertility?

Answer 21

+ It helps get lots of women pregnant

• It does not always work
• Too many eggs could be stimulated, resulting in unexpected multiple pregnancies (twins)

Question 22

What does IVF involve?

Answer 22

1. Collecting eggs from the woman’s ovaries and fertilising them in a lab using the man’s sperm. These are then grown into embryos
2. The embryos then split into tiny balls and one or two of them are implanted back into the woman’s womb. More than one embryo is implanted to improve the chance of pregnancy.
3. FSH and LH are given before the egg collection to stimulate egg production.

Question 23

What is the advantage of IVF?

Answer 23

1. Fertility treatment can give an infertile couple a child

Question 24

What are the disadvantages of IVF?

Answer 24

1. Some women can have strong reactions to the hormones
2. There have been some reports of an increased risk of cancer due to the hormonal treatment but it is not clear at the moment
3. Multiple births can happen if more than one of the embryos grows into a baby.

Question 25

What does IVF stand for?

Answer 25

In-vitro fertilisation