In vitro fertilization (IVF)
Normally, an egg and sperm are fertilized inside a woman's body. If the fertilized egg attaches to the lining of the womb and continues to grow, a baby is born about 9 months later. This process is called natural or unassisted conception.
IVF is a form of assisted reproductive technology (ART). This means special medical techniques are used to help a woman become pregnant. It is most often tried when other, less expensive fertility techniques have failed.
In Vitro Fertilization (IVF)
During IVF, eggs and sperm from the couple are incubated together in a laboratory to produce an embryo. A health care provider then places the embryo into the woman's uterus, where it may implant and result in a successful pregnancy.
The steps of IVF:
- Egg Retrieval
- Embryo Culture
- Embryo Transfer
Step 1: Superovulation
In this process, also known as ovarian stimulation, ovulation induction, or stimulation of egg maturation, a woman takes medication to stimulate the ovaries to make many mature eggs at one time.
These medications are given by injection for 8 to 14 days. A health care provider closely monitors the development of the eggs using transvaginal ultrasound and blood tests to assess follicle growth and estrogen production by the ovaries. When the eggs are mature—as determined by the size of the ovarian follicles and the level of estrogen—an injection of the hormone hCG initiates the ovulation process. A health care provider takes out (egg retrieval) the eggs 34 to 36 hours after the hCG injection.
This is the process used to remove the eggs from the ovaries so they can be fertilized. The procedure is performed in a physician's office as an outpatient procedure. A mild sedative and painkiller are often used during the procedure, and it normally takes about 30 minutes. The steps for egg retrieval are as follows:
- An ultrasound probe is inserted into the vagina to visualize the ovaries and the follicles, which contain the eggs.
- A needle is inserted through the wall of the vagina to the ovaries. Generally, ultrasound is used to guide the placement of the needle.
- Suction is used to pull the eggs from the ovaries into the needle.
A man provides a semen sample. If the sperm are healthy, they are centrifuged to concentrate them and reduce the volume, placed in a dish with the egg, and left overnight in an incubator. Fertilization usually occurs on its own. However, sometimes sperm are not able to fertilize the egg on their own. When this is the case, a single sperm is injected into an egg using a needle. This process is called intracytoplasmic (pronounced IN-truh-sahy-tuh-PLAZ-mick) sperm injection (ICSI). About 60% of IVF in the Unites States is performed with ICSI. The pregnancy rate is about the same for IVF using natural fertilization or ICSI.
If sperm cannot fertilize the egg without assistance, couples should consider genetic testing. This testing can determine whether the sperm have chromosome problems that might cause development problems in the resulting embryos.
Embryos that develop from IVF are placed into the uterus 1 to 6 days after retrieval.
When the fertilized egg divides, it becomes an embryo. Laboratory staff will regularly check the embryo to make sure it is growing properly. Within about 5 days, a normal embryo has several cells that are actively dividing.
- Couples who have a high risk of passing a genetic (hereditary) disorder to a child may consider pre-implantation genetic diagnosis (PGD). The procedure is done about 3 to 4 days after fertilization. Laboratory scientists remove a single cell from each embryo and screen the material for specific genetic disorders.
- According to the American Society for Reproductive Medicine, PGD can help parents decide which embryos to implant. This decreases the chance of passing a disorder onto a child. The technique is controversial and not offered at all centers.
Step 5: Embryo Transfer
This procedure is performed in a physician's office. The procedure is normally painless, but some women may experience cramping.
A health care provider inserts a long, thin tube through the vagina and into the uterus and injects the embryo into the uterus. The embryo should implant into the lining of the uterus 6 to 10 days after retrieval.
Sometimes the embryos are frozen and thawed at a later date for embryo transfer. This is often done when fresh embryos fail to implant or when a woman wants to preserve her eggs in order to become pregnant years later. Women either time implantation with their ovulation cycle or receive estrogen and progesterone medications to prepare their uterine linings for implantation.
Why IVF procedure is performed
IVF is done to help a woman become pregnant. It is used to treat many causes of infertility, including:
- Advanced age of the woman (advanced maternal age)
- Damaged or blocked Fallopian tubes (can be caused by pelvic inflammatory disease or prior reproductive surgery)
- Male factor infertility, including decreased sperm count and blockage
- Unexplained infertility
IVF involves large amounts of physical and emotional energy, time, and money. Many couples dealing with infertility suffer stress and depression.
A woman taking fertility medicines may have bloating, abdominal pain, mood swings, headaches, and other side effects. Many IVF medicines must be given by injection, often several times a day. Repeated injections can cause bruising.
In rare cases, fertility drugs may cause ovarian hyperstimulation syndrome (OHSS). This condition causes a buildup of fluid in the abdomen and chest. Symptoms include abdominal pain, bloating, rapid weight gain (10 pounds or 4.5 kilograms within 3 to 5 days), decreased urination despite drinking plenty of fluids, nausea, vomiting, and shortness of breath. Mild cases can be treated with bed rest. More severe cases require draining of the fluid with a needle.
Medical studies have shown so far that fertility drugs are not linked to ovarian cancer.
Risks of egg retrieval include reactions to anesthesia, bleeding, infection, and damage to structures surrounding the ovaries, including the bowel and bladder.
There is a risk of multiple pregnancies when more than one embryo is placed into the womb. Carrying more than one baby at a time increases the risk of premature birth and low birth weight. (However, even a single baby born after IVF is at higher risk for prematurity and low birth weight.)
It is unclear whether IVF increases the risk of birth defects.
IVF is very costly. Some, but not all, states have laws that say health insurance companies must offer some type of coverage. But, many insurance plans do not cover infertility treatment. Fees for a single IVF cycle include costs for medicines, surgery, anesthesia, ultrasounds, blood tests, processing the eggs and sperm, embryo storage, and embryo transfer. The exact total of a single IVF cycle varies, but may cost more than $12,000 to $17,000.
After the Procedure
After embryo transfer, the woman may be told to rest for the remainder of the day. Complete bed rest is not necessary, unless there is an increased risk of OHSS. Most women return to normal activities the next day.
Women who undergo IVF must take daily shots or pills of the hormone progesterone for 8 to 10 weeks after the embryo transfer. Progesterone is a hormone produced naturally by the ovaries that helps thicken the lining of the womb (uterus). This makes it easier for the embryo to implant. Too little progesterone during the early weeks of pregnancy may lead to miscarriage.
About 12 to 14 days after the embryo transfer, the woman will return to the clinic so that a pregnancy test can be done.
Call your health care provider right away if you had IVF and have:
- A fever over 100.5°F (38°C)
- Pelvic pain
- Heavy bleeding from the vagina
- Blood in the urine
Statistics vary from one clinic to another and must be looked at carefully.
- Pregnancy rates reflect the number of women who became pregnant after IVF. But not all pregnancies result in a live birth.
- Live birth rates reflect the number of women who give birth to a living child.
According to the Society of Assisted Reproductive Technologies (SART), the approximate chance of giving birth to a live baby after IVF is as follows:
- 41% to 43% for women under age 35
- 33% to 36% for women age 35 to 37
- 23% to 27% for women ages 38 to 40
- 13% to 18% for women age 41 and over
- Pelvic inflammatory disease (PID)
Courtesy: Eunice Kennedy Shriver National Institute of Child Health and Human Development.