IVF - How IVF is performed

The IVF technique was developed in the 1970s. It may differ slightly from clinic to clinic but a typical treatment is as follows.

For women

Step one: suppressing the natural monthly cycle

You are given a drug that will suppress your natural menstrual cycle. This is given either as a daily injection (which you'll be taught to give yourself) or as a nasal spray. You continue this for about two weeks.

Step two: boosting the egg supply

Once your natural cycle is suppressed, you take a fertility hormone called FSH (follicle stimulating hormone). These fertility hormones are known as gonadotrophins. This is another daily injection  you give yourself, usually for about 10-12 days, but it can vary depending on your response.

FSH increases the number of eggs your ovaries produce. This means more eggs can be collected and fertilised. With more fertilised eggs, the clinic has a greater choice of embryos to use in your treatment.

Step three: checking on progress

The clinic will keep an eye on you throughout the drug treatment. You will have vaginal ultrasound scans to monitor your ovaries and, in some cases, blood tests. About 34-38 hours before your eggs are due to be collected, you'll have a final hormone injection that helps your eggs to mature.

Step four: collecting the eggs

For the egg collection, you'll be sedated and your eggs will be collected under ultrasound guidance. This involves a needle being inserted through the vagina and into each ovary. The eggs are then collected through the needle.

Some women experience cramps or a small amount of vaginal bleeding after the procedure.

Step five: fertilising the eggs

The collected eggs are mixed with your partner's or the donor's sperm in the laboratory. After 16-20 hours they're checked to see if any have been fertilised.

If the sperm are few or weak, each egg may need to be injected individually with a single sperm. This is called intra-cytoplasmic sperm injection or ICSI (see below).

The fertilised eggs (embryos), continue to grow in the laboratory for one to five days before being transferred into the womb. The best one or two embryos will be chosen for transfer.

After egg collection, you will be given medicines, either progesterone or hCG (chorionic gonadotrophin), to help prepare the lining of the womb to receive the embryo. This is given either as a pessary (which is placed inside the vagina), an injection or a gel.

Step six: embryo transfer

The number of embryos to be replaced should have been discussed before treatment starts.

Women under 37 in their first IVF cycle should only have a single embryo transfer. In their second IVF cycle they should have a single embryo transfer if one or more top-quality embryos are available. Doctors should only consider using two embryos if no top-quality embryos are available. In the third IVF cycle, no more than two embryos should be transferred.

Women aged 37–39 years in the first and second full IVF cycles should also have single embryo transfer if there are one or more top-quality embryos, and double embryo transfer should only be considered if there are no top-quality embryos. In the third cycle, no more than two embryos should be transferred.

For women aged 40-42 years, double embryo transfer can be considered.

All multiple embryo replacements carry the risk of a multiple pregnancy and birth. Multiple pregnancies are associated with a significantly increased risk of premature labour, resulting in a three- to five-fold increased risk of blindness, deafness and cerebral palsy.

Read more about the risks associated with multiple births.

If any embryos are left over, and they're suitable, they may be frozen for future IVF attempts (see freezing and storing embryos on the HFEA website).

The embryo transfer is done either two to three days after egg collection (cleavage stage of embryo development) or five to six days after egg collection (blastocyst stage).

For more information about embryo transfer, read the HFEA factsheets on:

• embryo transfer
• blastocyst transfer
• assisted hatching (helping the embryo to break from its outer layer so it can attach to the wall of the womb)

For men

Around the time your partner's eggs are collected, you'll be asked to produce a fresh sample of sperm. The sperm are washed and spun at a high speed, so the healthiest and most active sperm can be selected.

If you're using donated sperm, it is removed from frozen storage, thawed and prepared in the same way.

Information on other techniques

There are many alternative methods to help a couple conceive. For more information, see the HFEA factsheets on:

• natural cycle IVF – IVF without fertility drugs and hormones to boost the supply of eggs
• intra-cytoplasmic sperm injection (ICSI) – injecting a single sperm directly into an egg to fertilise it
• intrauterine insemination (IUI) – separating fast-moving sperm from more sluggish or non-moving sperm
• gamete intra-fallopian transfer (GIFT) – placing the healthiest eggs and sperm together in the woman’s fallopian tubes so that fertilisation takes place in the body
• in vitro maturation (IVM) – maturing the eggs in the laboratory before fertilising them