Ever since Patrick Steptoe and Robert Edwards announced the birth of the first 'test-tube' baby in 1978, many thousands of babies have been born to couples as a result of IVF treatments who would otherwise have remained childless.

The main indications for IVF are when the woman's fallopian tubes are blocked or damaged, or when there are dense adhesions or endometriosis involving the ovaries. IVF may also be the treatment of choice when the sperm count is very low, and in certain cases of otherwise 'unexplained' infertility.

"In-vitro" means "in glass" and is the laboratory term used for a biological process that occurs outside the body. It was the media who popularised the term "test-tube" pregnancy. In fact, test tubes are not used in the actual IVF process, flat plastic dishes being used instead.

It must be remembered that IVF is not the be-all and end-all of all treatment. But if the fallopian tubes are severely distorted and blocked, IVF may be the only option open to you, which gives at least an opportunity for a pregnancy to occur.

If after preliminary investigations you are found to be suitable for IVF, very detailed explanation and counselling about the procedure will be given to both of you.

To better understand the principles behind treatment, it will help if you understand how normal egg production works in each cycle:

At the beginning of every normal menstrual cycle, the brain sends a message to the pituitary gland that lies just beneath it, to release a hormone called Follicle Stimulating Hormone (FSH). FSH stimulates a group of about 20 egg follicles to start growing. During the next 12 days, as these follicles grow, they produce a hormone called oestrogen. When the rising oestrogen output is recognised by the brain as having reached an adequate level, the pituitary gland is instructed to reduce the release of FSH. As a result, there is only enough FSH to allow the biggest 'leading follicle' in the group of 20 growing follicles to continue to develop to maturity. This explains why most human pregnancies are only a single baby.

In IVF we are deliberately trying to stimulate more of the group of 20 follicles to continue to grow so as to obtain a bigger "harvest" of eggs. To achieve this goal it is necessary to first "switch off" the normal control your pituitary gland has over your ovaries.

There are two ways of achieving this.

The standard method is to first "down regulate" the pituitary gland by stimulating it to use up all its stores of FSH. In our clinic we either use a drug administered by injection or occasionally via a nasal spray. Once there is evidence that the pituitary gland is suppressed, (and while still continuing the suppression treatment), your ovaries are stimulated with daily injections of FSH alone or in combination with LH.

An alternative method is to block the release of your own FSH while stimulating your ovaries to grow eggs. This newer method has the advantage of far fewer injections and a much shorter treatment cycle but the disadvantage of increased cost.

Therefore, unlike a natural cycle, the FSH levels are not allowed to fall, which means that hopefully more of the original group of 20 follicles continue to grow and mature. The progress in the growth of the follicles is monitored by ultrasound scans and by blood tests, which measure the rising level of oestrogen hormone. Once the ultrasound scan shows that there are a sufficient number of mature follicles, you are given a hormone injection of hCG which primes the eggs before they are collected.

At our centre, the whole process of egg stimulation, egg retrieval and subsequent embryo transfer is carried out on an outpatient basis.

Thirty-six to thirty-eight hours after the hCG injection, the eggs must be removed from the ovaries. This is a remarkably pain-free procedure. You will be offered sedation anaesthesia.

When our anaesthetist gives sedation, you will essentially feel nothing and actually remember nothing of the retrieval process.

The method of pain relief will be discussed with you when your treatment cycle is being planned and also by our anaesthetic staff.

The eggs are removed through the vagina using ultrasound to guide the direction of the fine needle that is used for this procedure.

On the day of egg retrieval your partner produces a sperm sample at the Centre. Our embryology team prepares this so that the most vigorous sperm are isolated.

The eggs usually require a few hours of incubation before they are mixed with the sperm, as they have been removed a little prematurely and need time to mature. When the eggs appear to be mature, each egg is incubated with up to 100,000 sperm. Fertilisation usually occurs in the next 12-16 hours.

Two, three or five days after the egg collection you will be asked to return to the ACU to have the two most promising embryos gently transferred into the uterus through the cervix. This is a painless procedure and does not require any anaesthetic. You will be required to remain horizontal for a short time after the embryo transfer and can then return home.

Under current regulations, the maximum number of embryos that may be transferred is two. In exceptional circumstances three embryos may be transferred to a woman over the age of 40 years. To many infertile couples the prospect of twins or even triplets is fantastic; a complete family in one go! But the reality can be very different.

The complications of a multiple pregnancy are significantly increased. There is a greater risk of miscarriage, raised blood pressure and diabetes. The majority of IVF twins and triplets are delivered by Caesarean section. The major antenatal complication in a multiple pregnancy is premature labour. Gross prematurity can sadly result in learning and development difficulties and even conditions such as cerebral palsy. The stillbirth and neonatal death rate (deaths in the first 28 days after birth) for triplet pregnancy with one or more of the babies dying is 59.6 per 1000 birth events (6.0%) compared to 9.9 per 1000 (1.0%) for a pregnancy with a single baby (HFEA 9th Annual Report 2000).

There are then the potential problems of looking after more than one baby at home. You may wish to consider only replacing one embryo if you feel unhappy at the prospect of a multiple birth. Please discuss this with the staff during your treatment. While it is ideal to transfer embryos nearer to the natural time they would enter the uterus (five days after ovulation), this very much depends upon the egg yield and the number and quality of the resulting embryos.

The whole question of the storage of any remaining embryos will have been fully discussed with you before the IVF cycle is even begun. We have the facility of embryo freezing and this will be offered to you to store suitable 'spare' embryos for your own possible future use. There is no point in storing embryos of dubious quality as this will raise false hopes that they will survive future thawing and be suitable for transfer, therefore only good quality embryos will be frozen.

During the next two weeks you will be using progesterone vaginal pessaries to support the lining endometrium of the uterus to encourage implantation of the embryo. 16 days after the egg retrieval, you will be asked to return to the ACU for a urine test and blood test that will hopefully detect the pregnancy hormone Beta-hCG. It is important to attend for the blood test even if you have started a period, so we can exclude the possibility of ectopic pregnancy.

There is some evidence that the use of low-dose aspirin improves the success of IVF. As long as you are able to tolerate aspirin it may be suggested to you to take this either from the commencement of the FSH injections or after embryo transfer has been carried out. The aspirin is continued until the result of the pregnancy test is known.

When the treatment cycle is being planned you are given very detailed oral and written information and implication counselling relating to IVF. This will include discussion on: abandoning a treatment cycle, coping with failed treatment, the problems linked to successful treatment especially a multiple pregnancy, the risks of ovarian hyperstimulation syndrome and ectopic pregnancy and the problems relating to cryopreservation (freezing) of any 'spare' embryos. A treatment consent form will be explained and both of you will be asked to sign this before treatment begins. The special HFEA consent forms relating to embryo storage are also explained and will need to be signed before egg retrieval.

This is only a very brief summary of what is involved in an IVF treatment cycle. You can perhaps understand and appreciate that emotionally it can be a very tense experience for both of you, especially the waiting time after embryo transfer. For this reason you will be offered support counselling with our counsellor both before and after embarking upon a treatment cycle.