What is in vitro fertilization (IVF)?
Reproduction inside the body (in vivo) occurs when an egg joins with sperm in the fallopian tube to form an embryo. The embryo then attaches to the uterus (womb) for pregnancy. In IVF, eggs are removed from the body, and eggs and sperm are joined in the laboratory to form embryos. These embryos are then placed into the uterus for pregnancy.
IVF treatment usually requires stimulation of the ovaries to produce multiple eggs using fertility medications, an egg retrieval procedure to remove eggs from the ovaries, fertilization (joining) of eggs and sperm in the laboratory to form embryos, growth and assessment of embryos for 3 to 5 days and finally the placement of embryo(s) into the uterus to achieve a pregnancy.
Step 1: Ovarian Stimulation:
In a typical menstrual cycle, only one mature egg is produced each month. To increase the chance of success in IVF, hormonal medications are given to stimulate the ovaries to produce and grow more eggs, which can be removed for the IVF process.
During this phase of treatment, you will be carefully monitored with blood hormone levels and internal (transvaginal) ultrasound measurements of follicular size.
Step 2: Egg Retrieval
The egg retrieval is performed by a doctor. The doctor will use an ultrasound to see the follicles and place a needle through the top of the vagina into the ovary. All of the follicles will be drained, and the fluid will be sent to the embryology lab to identify the eggs. Shortly after the retrieval, the number of eggs that were retrieved will be known and discussed with you.
The egg retrieval will be performed with sedation. Medications to relax you and provide pain relief will be given through an intravenous (IV) during the procedure. You will not be completely unconscious, but should be comfortable and able to tolerate the procedure.
Step 3: Fertilization
After the egg retrieval, if embryos are to be created, the embryology lab will fertilize the eggs by IVF or Intracytoplasmic sperm injection (ICSI). Fertilization is the process where the egg and sperm join together to form an embryo. Typically, it is expected that approximately 70-80% of mature eggs should fertilize. Your doctor will discuss which option for fertilization would be best in your situation based on your history and test results.
Step 4: Embryo Transfer
If an embryo transfer if planned, this will take place on day 3 or day 5 after the egg retrieval. You will have a discussion with the doctor and embryology team about your embryos. A final decision will be made about the number of embryos which will be transferred, based on age, medical history and the number and quality of the embryos.
The embryo transfer is performed by a doctor. An ultrasound is used to see the uterus, and the embryos are placed in the uterus using a small catheter (tube) through the cervix.
You will be instructed when a pregnancy test to see if the IVF was successful should be done. If the pregnancy test is positive, it will need to be repeated no sooner than 2 days later to confirm the pregnancy is growing appropriately.
Sometimes more embryos are produced than will be transferred during a fresh IVF cycle. Occasionally, for various medical reasons, it will be advised not to proceed with a fresh embryo transfer and to freeze all of the embryos. Embryos that are good quality can be frozen (cryopreserved) until you are ready to use them in the future. Embryos can be frozen for long time periods and still have a good chance to lead to pregnancy. Embryos must be of good quality and have developed to certain stages before they can be frozen.
Additional IVF Procedures
Each embryo is surrounded by a shell called the zona pellucida. The embryo at the blastocyst stage must hatch out of the shell in order to implant into the uterus. It is felt that in some situations, the embryo may not be able to properly hatch out of this shell to implant. Assisted Hatching is a laboratory procedure where a laser is used to thin or make a small hole in the shell around the embryo to make it easier for the embryo to hatch.
Assisted hatching may benefit those whose embryos were created with eggs retrieved after the age of 37, those with poor quality embryos, those with previous repeated IVF implantation failures, and frozen embryos. Assisted hatching may not benefit all individuals undergoing IVF treatment.
There is a theoretical risk of damaging the embryo with assisted hatching; however this has not happened in our experience due to the precision of the laser. Some studies have suggested there is an increased risk of identical (monozygotic) twins after assisted hatching.
Intracytoplasmic Sperm Injection (ICSI):
ICSI is a procedure in which a sperm is chosen and mechanically placed into an egg for fertilization. ICSI is used when sperm counts are low, sperm quality is poor, previous failed fertilization with IVF, unexplained infertility, pre-implantation genetic diagnosis (PGD) or when there are other concerns about fertilization.
Are there Risks with IVF and/or ICSI?
Most people will experience some bloating and fullness in the lower abdomen with the IVF cycles. This is a normal reaction to the injectable medications. Side effects may also include bruising and soreness at the injection site, allergic reaction, gastrointestinal distress, headaches or mood changes. It is important to discuss with your doctor if you experience any reactions to the medications.
Ovarian Hyperstimulation Syndrome (OHSS)
OHSS is a condition where there is an over-response to medications with the development of a large number of follicles and very high hormone (estrogen) levels. In severe cases, people will have fluid (water) build up in their abdomen and lungs and develop blood clots. The fluid may need to be removed with a needle and there may be a need to be admitted to the hospital for management. Severe OHSS can occur in 1-3% of people undergoing IVF. Rarely, an ovary that has been stimulated may twist (ovarian torsion), which may require surgery (<1%).
Risks associated with the egg retrieval include: discomfort during the procedure, bleeding, infection or puncture of bowel. Infections are rare, but severe infections may require antibiotics or rarely surgery.
The risks of sedation include being too sedated, breathing and/or heart rate complications.
In some situations, your IVF cycle may be cancelled before the egg retrieval. If your cycle is cancelled, a review appointment will be booked with your primary doctor and a portion of your costs will be refunded based on the treatments/procedures which have already occurred.
The goal of IVF is to produce one healthy baby. Multiple pregnancies are pregnancies with more than one baby (such as twins or triplets). This risk of having a multiple pregnancy is increased with IVF, especially when more than one embryo is placed in the uterus. Approximately 1 out of every 5 pregnancies after IVF is a multiple pregnancy. For those under 35 years of age, this risk can be much higher in some situations, and your doctor may recommend only placing ONE embryo during your treatment.
Even twin pregnancies can have many risks to the person carrying the pregnancy as well as to the babies. Risks with multiple pregnancies include miscarriages, premature delivery, or long-term health and developmental problems such as cerebral palsy.
There are also increased risks to an individual carrying a multiple pregnancy. This includes higher risks of high blood pressure and diabetes. You may also require bed rest or time off work much earlier. There is also an increased risk of problems with bleeding and problems at the time of delivery.
All pregnancies have a small risk that the babies can have a birth defect. The general risk for all pregnancies is approximately 3-5%. The risk of birth defects including cerebral palsy appears to be higher in those with infertility, even if they conceive without fertility treatment. The risk in babies born after IVF appears to be slightly increased (7%), but not statistically different from those with infertility who conceive without the use of fertility treatments. The risk is slightly higher after ICSI (10%).
Other problems which can occur in pregnancy may also occur in an IVF pregnancy. In particular, miscarriages (spontaneous abortions) occur in approximately 15%-30% of IVF pregnancies (depending on age) and ectopic pregnancies (pregnancy in the fallopian tube) will occur in about 2% of IVF pregnancies.
Studies have also shown that pregnancies conceived through IVF are more likely to have some pregnancy complications including high blood pressure, premature delivery, operative delivery, and small babies. There is no evidence that children born from IVF have neurological or health effects, although further long-term studies are needed.