If a couple has been trying to conceive for a year without success, doctors will usually start to perform tests for infertility.

Common causes of female infertility include failure to ovulate or produce an egg and blocked fallopian tubes, which can sometimes be unblocked by surgery.

In males, common causes of infertility include failure to produce enough sperm, problems with the tube that carries sperm, and problems with the testicles, which can be caused by having mumps as a teenager or younger adult.

Fertility in both sexes also drops significantly with age.

When a couple's infertility can't be treated with drugs or surgery, assisted reproduction may be an option. There are now several techniques to help infertile couples conceive, but the best-known is IVF.

HOW IS IT DONE?

An IVF procedure usually begins by giving the woman hormones to stimulate her ovaries so that she produces more than the usual one egg per cycle. This lets her doctor harvest several eggs during one procedure. These can be stored in case fertilisation does not succeed the first time.

Before harvesting the eggs, one or two blood tests and ultrasounds are done to monitor the eggs' development in the menstrual cycle. The tests ensure the eggs are collected at the right time, when they are mature.

Harvesting is carried out under light general  anaesthetic. The ultrasound is inserted into the vagina and a very fine needle is threaded through a guide, which is attached to a probe. The ultrasound shows where the follicles are. The needle pierces them and extracts follicular fluid, which contains the egg.

The man provides a semen sample, which is placed with the woman's eggs into a special dish in a laboratory.

For very infertile couples, another form of IVF known as ICSI (intracytoplasmic sperm injection) may be used. In this case, one sperm is injected directly into the egg to increase chances of conception. If an egg is fertilised by a sperm, a zygote or pre-embryo will begin to develop. This is left in an incubator for one or two days sometimes five days, until it has divided into two or four cells.

Following fertilisation, two to three embryos will be transferred to the uterus using a soft, fine catheter. This procedure, known as embryo transfer, is similar to a smear test and requires no anaesthetic.

WHAT ARE THE RISKS

The increase in the hormone oestrogen can cause breast tenderness, nausea, dizziness and slight abdominal swelling.

Occasionally, a condition called ovarian hyperstimulation syndrome can occur. This may include marked abdominal swelling, nausea, vomiting and diarrhoea, lower abdominal pain and shortness of breath.

There is also a very slight risk of the collection needle damaging organs, or causing infection or bleeding.

RECOVERY

Two weeks after the transfer, a blood test is given to see if the woman is pregnant.

Most patients need more than one treatment. On average, a couple has a 30 per cent chance of having a baby after one attempt at pregnancy using assisted reproductive technology.

Despite the advances in IVF technology, some couples are forced to accept that they can never have children. This can be very traumatic.

Specialist infertility counsellors are available at both private infertility consultation and infertility clinics ofour hospital.