The use of hormones to treat infertility (HT only): Students should be able to explain the use of hormones in modern reproductive technologies to treat infertility.

The idea

Infertility can be treated using hormones. If a woman's own FSH level is too low to stimulate eggs to mature, a 'fertility drug' containing FSH and LH can be given. This stimulates egg maturation and ovulation, allowing normal pregnancy. Alternatively, In Vitro Fertilisation (IVF) is used. In IVF, the woman is given FSH and LH to stimulate several eggs to mature. Eggs are collected before release and mixed with sperm in a laboratory so fertilisation occurs outside the body. The resulting embryos are grown briefly and one or two are transferred to the uterus to implant. These technologies raise ethical issues, including the fate of unused embryos and the risk of multiple births.

What earns the marks

• A fertility drug containing FSH and LH can be given to women with low FSH to stimulate egg maturation and ovulation for normal pregnancy.
• In IVF, FSH and LH are given to stimulate the maturation of several eggs in the ovaries.
• Eggs are collected from the mother and fertilised by sperm from the father in the laboratory.
• The fertilised eggs develop into embryos outside the body.
• At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother's uterus.
• The use of these technologies raises ethical issues, such as what happens to unused embryos and the risk of multiple births.

Common mistakes and how to put them right

• Saying that FSH causes ovulation.

  Put it right: FSH causes eggs to mature, while LH triggers ovulation.

• Thinking that IVF fertilisation happens inside the woman's body.

  Put it right: Fertilisation occurs outside the body in a laboratory, and only the embryo is transferred to the uterus.

• Stating that eggs are collected after ovulation.

  Put it right: Eggs are collected before they are released, after hormones have triggered maturation.

• Forgetting that fertility drugs can be used for normal pregnancy.

  Put it right: FSH and LH can be given simply to stimulate ovulation without IVF.

Exam tips

• Use the correct sequence for IVF: stimulate eggs with FSH and LH, collect eggs, fertilise outside the body, transfer embryos to the uterus.
• When describing hormone use, name each hormone and give its specific role rather than saying they 'help eggs grow'.
• Include one ethical point, such as the status of unused embryos, when a question asks for evaluation or discussion.