Causes of infertility

1. Infertility has several causes, and only some of them can be treated with hormones.
2. If the pituitary gland secretes too little FSH, no follicle is stimulated and no egg matures.
3. If it secretes too little LH, an egg may mature but ovulation never happens.
4. Both of these causes are hormonal, so giving the missing hormone can restore the cycle.
5. Blocked oviducts stop sperm reaching the egg, and hormones cannot clear the blockage.
6. A low sperm count or poorly swimming sperm also prevent fertilisation, and again hormones do not help.
7. Treatment is chosen to match the cause, so the first step is always to find out which part of the process is failing.

Fertility drugs

1. A fertility drug contains FSH and LH, the same hormones the pituitary gland normally secretes.
2. The drug is given by injection over the first part of the cycle.
3. FSH stimulates follicles in the ovaries so that eggs mature.
4. LH is then given to trigger ovulation, releasing the mature eggs into the oviducts.
5. The natural cycle is restored, so the couple can conceive through intercourse in the usual way.
6. Because the dose stimulates more than one follicle, several eggs can be released at once.
7. That raises the chance of twins or triplets, which carries greater risk for the mother and the babies.

Steps in IVF

1. FSH and LH are given first, so several eggs mature in the ovaries at the same time.
2. The mature eggs are collected from the ovaries through a fine needle.
3. Each egg is mixed with the father's sperm in a dish in the laboratory, where fertilisation takes place.
4. The fertilised eggs are kept in an incubator and allowed to divide into embryos.
5. When each embryo is a small ball of cells, one or two are inserted into the uterus through the cervix.
6. Progesterone is often given so the uterus lining is maintained and the embryo can implant.
7. A pregnancy test taken about two weeks later shows whether implantation was successful.
8. Any remaining embryos can be frozen and stored for a later attempt.

Evaluating IVF

1. IVF allows couples who could not conceive naturally to have a child of their own, which is its main benefit.
2. Success rates are low, at roughly $32\%$ of cycles for patients under $35$ and falling below $5\%$ above the age of $43$.
3. Several attempts are often needed, so the emotional strain of repeated failure is considerable.
4. The hormone injections have physical side effects including abdominal pain, vomiting and, rarely, a dangerous over-response of the ovaries.
5. Transferring more than one embryo raises the chance of multiple births, which brings a higher risk of premature birth and low birth mass.
6. Each cycle is expensive, often over £5000\pounds5000£5000 privately, and funding on the NHS varies between areas.
7. Spare embryos are frozen or destroyed, and some people object to this because they regard an embryo as a potential life.
8. A judgement therefore weighs the chance of a much wanted child against the cost, the risks and the ethical objections.