5.3.6 The use of hormones to treat infertility
Fertility Drugs Can Trigger Ovulation
Definition
FSH (follicle-stimulating hormone)
A hormone from the pituitary gland that causes an egg to mature in the ovary and stimulates the ovaries to produce oestrogen.
- Some women do not make enough FSH, so their eggs do not mature and they do not ovulate.
- They can be given FSH and LH as a fertility drug.
- The FSH makes eggs mature and the LH triggers ovulation, so the woman may then conceive naturally.
- Because several eggs can mature at once, there is a raised chance of a multiple birth.
Key Idea
A fertility drug supplies the FSH and LH a woman is not making enough of, so her eggs mature and she can ovulate.
IVF: Fertilising Eggs Outside the Body
Definition
IVF (in vitro fertilisation)
A fertility treatment in which eggs are collected and fertilised by sperm in the laboratory, and one or two resulting embryos are placed into the uterus.
- The mother is given FSH and LH to make several eggs mature at once.
- The eggs are collected from the ovaries.
- The eggs are fertilised with sperm from the father in the laboratory.
- The fertilised eggs develop into embryos.
- At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother's uterus.
Note
IVF depends on advances in microscopy and micro-tools that let scientists handle single eggs, sperm and embryos without damaging them.
Evaluating Infertility Treatment
- The main benefit is that couples who could not conceive naturally may have a baby of their own.
- However, the treatment is very emotionally and physically stressful.
- Success rates are not high, and they fall as the mother gets older.
- It can lead to multiple births, which are risky for both the mother and the babies.
- It is expensive, and unused embryos raise ethical questions.
Example
IVF success falls sharply with age, from around a third of attempts for women under 35 to only a few per cent for women over 44.
Fertility Treatment at a Glance
- A fertility drug gives FSH and LH so eggs mature and ovulation happens.
- In IVF, FSH and LH mature several eggs, which are collected and fertilised in the laboratory.
- Early embryos are then placed back into the uterus.
- The treatment offers hope but is stressful, costly, not always successful and can cause multiple births.
Self review
- Which hormones are given in a fertility drug, and why?
- List the main steps of IVF in order.
- Why does fertility treatment often lead to multiple births?
- Give two disadvantages of fertility treatment.
- How does the mother's age affect the success rate of IVF?
