What is IVF?
When a couple conceives naturally, sperm from the man and the egg from the woman meet in the woman’s fallopian tubes.
These are the tubes that join the ovaries to the uterus (womb). One sperm penetrates the egg and fertilises it.
In IVF, this process of fertilisation happens outside the woman’s body. A woman’s eggs are surgically removed and fertilised in a laboratory using sperm that has been given as a sperm sample.
Next, the fertilised egg, called an embryo, is surgically implanted into the woman’s womb.
Typically, one cycle of IVF takes between four and seven weeks.
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.
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. It’s also a good idea to follow a healthy protein rich diet while you are preparing for IVF.
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.
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.
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.