In most cases, IVF involves 3 steps:
The ovaries make one mature egg a month from a follicle. Though sometimes more than one can happen. In this part of IVF, hormones are used so the ovaries make several mature eggs. Often, more than one embryo is placed in the uterus to boost the chances of a pregnancy. But, it also makes the chances of having more than one baby higher. Having more than 2 babies can cause a high-risk pregnancy. The doctor will not place more embryos than are needed.
Hormones used to boost the ovaries are:
- Human menopausal gonadotropins (hMG)
- Follicle stimulating hormone (FSH)
- Human chorionic gonadotropin
- Clomiphene citrate—given as a pill
These medicines are used for 8 to 14 days. They are often given with:
- Gonadotropic releasing hormone (GnRH) agonists
- GnRH antagonists
Using these will help keep ovulation from happening too soon.
The ovaries are watched during an ultrasound. This will let the doctor track how well the ovaries are doing. Blood tests can also track the body's hormones levels during the IVF cycle. They will change based on what part of the cycle you are in.
An hCG (or other hormone) shot is given to help the follicles mature when there are enough. After 1 to 2 days, the eggs are retrieved.
IVF cycles can be stopped before the hCG shot. This may happen if there are not enough follicles.
Your doctor will go over the risks involved with using hormonal medicines.
Egg Retrieval and Fertilization
Egg retrieval is a minor procedure that can be done in a doctor's office or clinic. It takes less than 30 minutes. Pain medicine may be given before it is started.
An ultrasound guided needle is often used to retrieve the eggs. They are placed in the vagina. Sound waves make it easier to see the ovaries and follicles. The needle is placed into the ovary to draw out eggs and some fluid.
This may cause cramping, but it usually goes away in a day or so. A feeling of fullness or pressure in the belly is caused by larger ovaries. This is normal. It can take many weeks for this to go away.
The eggs are looked at in a lab. Those that are mature and of good quality will be placed in a dish in an incubator waiting to be fertilized by sperm.
The man who is giving the semen should not ejaculate for 2 to 3 days. The healthiest sperm are chosen from the semen. They are mixed in the dish with the mature eggs. The sperm will fertilize most of them within hours. After a few days, embryos are placed into the uterus. This is called embryo transfer.
Sometimes, the sperm and eggs do not fertilize on their own. Intracytoplasmic sperm injection (ICSI) may be an option. ICSI is the process of taking a single sperm and injecting it into the egg. Assisted hatching (AH) is another way to help the process. AH involves making a hole in the shell before the transfer. This helps with the hatching of the embryo. It has helped older women and couples who have failed with other IVF cycles. AH may help increase the chances of pregnancy.
Egg retrieval is generally safe. Possible problems may include:
- Excess bleeding
- The ovary ruptures—rare
It takes about 3 to 6 days until the embryos are ready to be transferred into the uterus. Keep in mind not all IVF cycles result in embryos that can be used. If this is the case, the transfer will not happen. Before the transfer, a mild sedative may be given to help with relaxation.
You and the doctor will decide how many embryos to transfer. This can depend on age, other IVF tries, or what you want. The best quality embryos will be chosen for the transfer.
The embryos and a small amount of fluid are drawn through a long thin tube into a syringe. The doctor will place the syringe through the vagina and cervix, and into the uterus. Imaging will be used to help the doctor find the right place to implant them.
This does not cause pain, but there may be some cramping. The risks include:
- Multiple pregnancy—Having more than twins can lead to a high-risk pregnancy. In some cases, the number may be reduced to help better the chances of success.
- Ectopic pregnancy—The embryo develops outside of the uterus.
You will need to stay in bed for 15 minutes to 6 hours. At home, you will need to limit activity and or stay in bed for 1 to 2 days. Your doctor may give you progesterone to help increase your chances of success.
If there are any embryos left, they can be frozen. These can be stored for many years until they are needed. Then, they can be thawed out and used in other transfers.
A blood test will be done in 2 weeks to see if you are pregnant.
Other Types of IVF
There are other types of IVF available. These include:
Gamete intrafallopian transfer (GIFT)—During egg retrieval, the eggs and sperm are transferred into a syringe and working fallopian tube right away. This can be done if there is enough sperm to fertilize the egg. Since the transfer is done right away, there is no time to check the quality of the egg.
Zygote intrafallopian transfer (ZIFT)
—This uses IVF and GIFT. Fertilization happens in a lab, then a transfer is done into the fallopian tubes. Fertilization is confirmed, but embryo growth is not.
GIFT and ZIFT more closely match how this happens naturally. The egg is fertilized by sperm in the fallopian tube. Then, the embryo moves into the uterus to implant.