What is IVF, and how does it work?

What is IVF?

In vitro fertilization (IVF) is a procedure that may be able to help you get pregnant. It's the main type of assisted reproductive technology (ART), and has been in use since the 1970s.

When you do IVF, your eggs are extracted and combined with sperm in a petri dish ("in vitro" means "in glass" in Latin). IVF can be done using an egg and sperm from you and your partner, or you can use donor eggs and/or donor sperm.

After IVF, the embryo or embryos that result are transferred to your uterus through the cervix. If all goes well, an embryo will implant  in your uterine lining and continue to develop.

The use of ART has more than doubled over the past decade, according to the Centers for Disease Control and PreventionOpens a new window (CDC). About 2 percent of all infants born in the United States each year are conceived using ART.

"Assisted reproductive technology has helped so many individuals and couples on their path to parenthood who otherwise may have never had that chance," says Sasha Hakman, M.D., a double board-certified ob-gyn and reproductive endocrinologist with HRC FertilityOpens a new window in Los Angeles.

"We're so lucky to live in a time where we have this option at our disposal," says Dr. Hakman, who specializes in treating infertility and is a member of the BabyCenter Medical Advisory Board.

Why choose IVF?

IVF can help you get pregnant if you or your partner have problems with:

• Ovulation
• Egg quality
• Blocked fallopian tubes
• Endometriosis
• Sperm count or motility
• Unexplained infertility (when all fertility tests come back normal and the problem can't be identified)

IVF is also part of the journey to parenthood for some LGBTQ+ families, people using a gestational carrier (surrogate), and single parents by choice.

What happens before in vitro fertilization?

Before undergoing any IVF procedures, you'll have preconception testing and fertility testing.

Preconception testing includes:

• An antibody screen to test for immunity to rubella and chicken pox
• An option for genetic carrier screening to help identify your risk of having children with genetic diseases
• Infectious disease testing for hepatitis B and C , HIV, syphilis, gonorrhea, and chlamydia
• Blood type testing, including Rh status
• A pap smear

Fertility testing includes:

• Ovarian reserve testing, called Anti Mullerian Hormone (AMH), to determine the number of eggs you have available
• Hormone testing (TSH and anything else that might be applicable, based on your history)
• Uterine evaluation, to make sure your uterus is healthy enough to carry a pregnancy
• Reviewing your partner's semen quality

Your doctor may recommend a trial (or mock) transfer. This is a practice run of the procedure, without the transfer of any embryos. During the trial, the doctor uses an empty embryo transfer catheter to determine the best path through your cervix to your uterus.

How does in vitro fertilization work?

Once all the preliminaries are taken care of, IVF treatment usually goes something like this:

1. Ovarian stimulation. For eight to 14 days near the beginning of your menstrual cycle, you take a gonadotropin, a type of fertility drug that stimulates your ovaries to develop multiple mature eggs for fertilization (instead of just one). You'll also need to take a synthetic hormone like leuprolide or cetrorelix to keep your body from releasing the eggs too early.

2. Follicle development. While taking these medications, you'll visit your doctor's office or clinic every two to three days to have your blood hormone levels checked and ultrasound measurements of your follicles done. (Follicles are the fluid-filled sacs in your ovaries that each contain an egg.)

3. The trigger shot. When the follicles are ready, you get a "trigger shot," an injection that causes the eggs to mature fully and become capable of being fertilized. About 36 hours after your trigger shot, your eggs are ready to be retrieved.

4. Gathering the eggs. Your doctor gives you an anesthetic and inserts an ultrasound probe through your vagina to look at your ovaries and identify the follicles. A thin needle is then inserted through the vaginal wall to remove the eggs from the follicles. Eight to 15 eggs are usually retrieved. You may have some cramping and spotting for a few days afterward, but most women feel better in a day or two. Unless you're using donor sperm, sperm will be collected from your partner at this same appointment.

5. Fertilization. An embryologist (a scientist who specializes in eggs, sperm, and embryos) will examine your eggs before combining them with the sperm and incubating them overnight. Fertilization usually happens during this time.

If sperm quality is poor, or if fertilization was unsuccessful during previous IVF cycles, your doctor may recommend using a technique called intracytoplasmic sperm injection (ICSI). With ICSI, a single sperm is injected directly into each mature egg.

6. Developing embryos. Three days after the egg retrieval, some of the eggs that were successfully fertilized become six- to 10-celled embryos. By the fifth day, some of these embryos will become blastocysts with a fluid-filled cavity and cells that are beginning to separate into the placenta and baby.

7. Embryo selection. The embryologist selects the most viable embryo or embryos to place in your uterus three to seven days after the egg retrieval. Extra embryos, if there are any, may be frozen and used for future IVF cycles.

8. Placing the embryos. Depending on your age and diagnosis, your doctor places between one and five embryos in your uterus by inserting a thin tube (a catheter) through your cervix. You might feel some mild cramping, but you won't need anesthesia. In most cases only one embryo is transferred at a time. If more than one embryo is transferred, your chance of pregnancy is higher, but so are the odds of having twins or multiples.

9. Successful implantation. If the treatment works, an embryo implants in your uterine wall and continues to grow into a baby. If at any time during the IVF cycle your doctor feels that conditions aren't promising (your hormone levels are lower than necessary, fertilization failed, or no eggs are retrieved, for example), they will cancel the cycle.

You can take a pregnancy test about 9 to 12 days after the embryos are placed in your uterus. If it's positive, you'll be advised to repeat it in a couple of days. If it's negative, your physician will advise you to stop taking the medication you were given to support the pregnancy.

How long will IVF take?

It takes about four to six weeks to complete one cycle of IVF.

• After taking drugs to stimulate your ovaries, you'll wait – usually a few weeks – for your eggs to mature. Then you'll spend a few hours at your doctor's office or clinic having your eggs retrieved and fertilized.
• You may go back again three to seven days later to have the embryos inserted into your uterus. You'll be able to go home that same day.

Then it's a matter of waiting to see if the embryo successfully implants in your uterus.

If you're using already-frozen embryos, the embryo transfer process is quicker, since IVF has already been completed. You'll take medications to prepare the uterine lining, and be monitored until your lining is ready for the embryo transfer. This typically takes about 19 to 21 days, but it might be longer or shorter, depending on your response to the medications. Following the transfer, you'll wait for successful implantation.

The long waiting period, along with the procedures, can be stressful. According to the Society for Assisted Reproductive Technology (SART), "patients have rated the stress of undergoing IVF as more stressful than or almost as stressful as any other major life event, such as the death of a family member or separation or divorce."

Being well informed about the process and asking for support can help. Learn more about how to cope with the emotional toll of infertility and prepare for and cope with the emotional considerations of IVFOpens a new window.

What is natural cycle IVF?

Natural cycle IVF is performed without the use (or with limited use) of medications – the injectable fertility drugs that are routinely given. Sometimes just one medication, the hCG trigger shot, is used.

The medications are expensive, and using them means more office visits and more testing. To make the process more affordable and attractive to some patients, some clinics offer IVF without injectable drugs. While this approach reduces the cost of the procedure, it also reduces the success rate, because fewer eggs are available.

Natural cycle IVF might appeal to patients who:

• Are at risk of ovarian hyperstimulation syndrome (which can be triggered by medications)
• Aren't interested in embryo cryopreservation (freezing), and so don't need to produce a number of eggs for fertilization
• Want to limit the number of eggs to be fertilized (for ethical or religious reasons)
• Don't have many follicles that develop mature eggs, despite receiving injectable medications

There are also variations of natural cycle IVF. A "mini IVF" procedure, for example, uses a lower dose of medication to create a smaller number of eggs than traditional IVF.

What's the success rate for IVF?

Here are the success rates for IVF procedures, based on national data collected for 2020 and preliminary data for 2021.

Using a patient's own eggs, the success rate for women undergoing IVF in 2021:

• 45% for women age 34 and under
• 32% for women age 35 to 37
• 20% for women age 38 to 40
• 10% for women age 41 to 42
• 3% for women age 43 and over

But to achieve the numbers above may take more than one transfer. On the first embryo transfer, the success rates for women using their own eggs are:

• 37% for women age 34 and under
• 28% for women age 35 to 37
• 18% for women age 38 to 40
• 9% for women age 41 to 42
• 3% for women age 43 and over

IVF success rates are higher when using donor eggs, because donor eggs are only retrieved from women who are young and healthy. For all ages, IVF using fresh donor eggs has an overall success rate of 41%, and using frozen donor eggs has a success rate of 40%.

Thawed embryos have an overall success rate of 46%, and donated embryos have an overall success rate of 42%.

SART provides tools for estimating your individual chances of IVF successOpens a new window, and the CDC has a similar IVF success estimatorOpens a new window.

What are the pros of IVF?

• Successful track record. IVF is the oldest assisted reproductive technology (ART) procedure – it's been around since 1978. IVF has been used long enough for researchers to have done extended health studies on the children conceived using this method. So far, no medical problems have been directly linked to the procedure.
• Improved techniques. Researchers continue to refine and improve IVF procedures. For example, advances in embryo freezing have resulted in IVF pregnancy rates that are about the same for frozen and fresh embryos.

We now know, too, that there's no link between IVF and cancer. Early studies suggested that exposure to fertility drugs might lead to a higher risk of ovarian cancer or other cancers of the female reproductive system. But recent studies have shown no connection.

A recent analysisOpens a new window of 29 studies published in Human Reproduction concluded that "Overall, fertility treatment does not significantly increase the incidence of ovarian, breast, or endometrial cancer and may even reduce the incidence of cervical cancer."

What are the cons of IVF?

• Cost and time. Fertilizing your eggs outside of your body requires costly lab work and medications. Monitoring your response to fertility drugs also requires a lot of time, with frequent trips to the doctor's office for blood tests and ultrasounds.
• Odds of multiples. Because more than one embryo may be placed in your uterus, your chance of having twins or more is increased with IVF. Though many couples consider this a blessing, multiple fetuses increase your risk of miscarriage and other complications, such as preterm delivery.
• Risk of ectopic pregnancy. Women who have difficulty getting pregnant and older women have an increased risk for ectopic pregnancy, and this can happen to those who conceive via IVF. An ectopic pregnancy occurs when an embryo implants in a fallopian tube or the abdominal cavity rather than in the uterus. Unfortunately, there's no way to save an ectopic pregnancy. Treatment involves medication or surgery to end the pregnancy.
• Risk of ovarian hyperstimulation syndrome (OHSS). OHSS can happen when women respond too well to fertility drugs and produce too many eggs. About 10 to 20% of women who take gonadotropins develop a mild form of OHSS, a condition marked by weight gain and a full, bloated feeling. Some also have shortness of breath, dizziness, pelvic pain, nausea, and vomiting. If you have OHSS, your ovaries swell to several times the normal size and produce fluid that accumulates in your abdominal cavity. Normally this resolves itself with careful monitoring by a physician and bed rest. But in rare cases, OHSS is severe and may be life-threatening. If this happens, you may have to be hospitalized for more intensive monitoring or treatment.
• Potential complications for the baby. Babies conceived via IVF may be more likely to be born prematurely or have a low birth weight (even if they're singletons). They may also have a slightly higher risk of birth defects. But experts aren't sure whether that's due to the factors that cause infertility (such as age) or infertility treatments.
• It may not work. Up to 20% of IVF cycles may be cancelled before eggs are retrieved, usually because not enough follicles developed. Even if the cycle isn't cancelled, the embryo may not successfully implant and develop.

What does IVF cost?

In the United States, expect to spend an average of about $20,000 to $25,000 for one cycle of IVF, once you include evaluation, medication, bloodwork, egg retrieval, the transfer procedure, and follow-up care. (One cycle means one egg retrieval procedure and all the embryo transfers that result from that retrieval.)

IVF costs vary a great deal, though, depending on how much medicine you need, where you live, whether you have insurance coverage for fertility treatments, and whether you add specialized procedures. Many insurers don't cover assisted reproduction technology, which would mean you'd need to pay the entire cost up front.

Some insurers will cover part of the cost – say consultations and blood work, for example. Others may pay for everything but have a cap on the total expenditure.

Make sure you iron out your coverage with your insurer before you start the process. And keep in mind that you'll have to account for any unpaid time off, as well as travel and accommodation expenses if you travel to a clinic that's not close to home.

Learn more:

• Does sex selection work?
• Early signs of pregnancy
• What is an egg shower?
• Egg freezing