What Is In Vitro Fertilization (IVF)?
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Medically reviewed by Soma Mandal, MD
In vitro fertilization (IVF) is a type of assistive reproductive technology (ART) that joins an egg and a sperm cell in a laboratory dish with the goal of creating an embryo. In the United States, ART cycles have increased by 44% over the past six years and more than doubled in the past decade. Currently, about 2% of babies are born using ART.
Though people commonly refer to the entire process of collecting and fertilizing eggs as IVF, the term IVF specifically only relates to the fertilization technique used. Translated from Latin, "in vitro" means "in glass." In the scientific community, it's used to describe studies and procedures that occur in an artificial environment outside of the body. Put simply, in vitro fertilization means fertilization that occurs in a petri dish rather than a human body.
However, people often use "IVF" as an umbrella term to describe the entire process of growing, retrieving, and fertilizing eggs, as well as developing and transferring embryos. From start to finish, the entire process can take up to six weeks or more, depending on which tests and medications your fertility specialist orders and whether you plan to freeze or transfer embryos.
The process requires time and energy, and it can be quite expensive. There are some risks, and success rates depend on various factors. However, it's a hopeful option for many people looking to build and expand their families.
Purpose of IVF
There are many reasons why someone might use IVF to build their family. While most people think of IVF primarily as a treatment for infertility, it's also used by people looking to preserve their fertility by creating and freezing embryos instead of eggs or sperm. IVF is also a powerful family-building tool for same-sex couples as well as single parents looking to conceive through egg or sperm donation.
Not everyone experiencing infertility will need IVF to build their families. Your fertility specialist may recommend other treatments such as timed intercourse and intrauterine insemination, where sperm is placed directly into the uterus, before moving on to IVF.
IUI vs. IVF
Intrauterine insemination (IUI) is a fertility treatment that involves placing sperm directly into the uterus using a thin tube called a catheter. Fertility specialists often recommend about three rounds of IUI before trying IVF. Research shows that pregnancy likelihood increases with multiple rounds of IUIs.
IUI is less invasive, expensive, and time-consuming than IVF. It might be the first approach used in fertility treatment if you have unexplained infertility or if you cannot do IVF.
Some fertility challenges that may lead to the use of IVF include:
Fallopian tube damage or blockages: Fallopian tubes are tubes that carry eggs from the ovaries to the uterus. About 30-40% of infertility is related to tubal damage or blockage.
Endometriosis: This condition occurs when tissue that is similar to the lining of the uterus (known as the endometrium) grows outside the uterus. It's more common in people with infertility.
Low sperm count or motility: Low-quality semen is either the primary cause or a contributing factor in about 40% of infertility diagnoses.
Ovulation disorders: About 25% of infertility is related to an ovulation disorder. Ovulation occurs about halfway through your menstrual cycle. An egg is released from an ovary and travels down a fallopian tube to prepare for possible fertilization and pregnancy. Ovulation disorders are conditions that cause irregular menstrual cycles. For example, polycystic ovarian syndrome (PCOS) occurs when the ovaries produce more male sex hormones than usual. This can cause anovulatory periods (menstrual bleeding without ovulation) or amenorrhea (no periods).
Unexplained infertility: About 15-30% of couples are diagnosed with infertility even though fertility tests show no abnormalities.
Jamie Wolff, Health Editor
"I went to a fertility specialist after trying to conceive naturally for about six months. I was concerned about my ability to get pregnant because I had a history of irregular periods. My PCOS diagnosis provided me with valuable information on how to proceed."
IVF is also an option for the following scenarios:
Using a donor: Using a sperm, egg, or embryo donor to get pregnant. You may choose donor conception if you and your partner share the same sex cells, if you or your partner cannot conceive using your own genetic material, or if you are looking to build your family as a single parent.
Reciprocal IVF: An option used by lesbian couples where one partner uses their egg to create an embryo and the other partner carries the embryo
Fertility preservation: Freezing and using embryos later in life (oocyte preservation)—for example, if you're undergoing chemotherapy or radiation treatments that might affect ovarian function
Genetic condition: Doing IVF to screen embryos for genetic conditions and select embryos without the disease
Using a gestational carrier: When someone carries a fetus through pregnancy for another person or people
A gestational carrier is not the same as a surrogate. Both terms refer to a person who carries a fetus through pregnancy for someone else. However, there's a key difference:
A traditional surrogate is inseminated with someone's sperm, which combines with their own egg to form an embryo. A surrogate is biologically related to the embryo. This type of surrogacy is rarely used these days due to complicated ethical and legal considerations.
A gestational carrier has an embryo transfer. The embryo is created with a third-party egg and sperm (an egg from one person and sperm from another person). A gestational carrier is not biologically related to the embryo.
People who choose to use a gestational carrier include:
Individuals or couples who cannot conceive due to infertility
People who cannot safely carry a pregnancy due to a medical condition
Same-sex couples
Nonbinary, intersex, and transgender individuals or couples
Single males
How Does IVF Work?
Fertilization is the combining of an egg and a sperm. The terms “in vivo” and “in vitro” refer to the location where fertilization occurs:
In vivo: Fertilization occurs inside the body
In vitro: Fertilization occurs outside the body, in a laboratory
In-vivo fertilization occurs naturally with sexual intercourse. When the male sperm reaches a female egg, it fertilizes it. This creates an embryo. If the embryo implants in the uterus (womb), pregnancy occurs.
With in vitro fertilization, fertilization occurs in a laboratory (petri) dish. The goal is for the fertilized embryo to implant in the uterus, resulting in pregnancy.
There are five basic stages of an IVF cycle:
Preparation
Ovarian stimulation
Egg and sperm retrieval
Egg fertilization in a laboratory dish
Embryo transfer into the uterus
You will work with a fertility specialist, probably in a fertility clinic. A reproductive endocrinologist (RE) is a gynecologist who specializes in fertility and infertility.
Preparation
You'll have a number of tests before you begin a cycle of IVF. These tests increase the possibility of success. They might include:
General blood tests: These include blood type and sexually transmitted infection (STI) screening for conditions like human immunodeficiency virus (HIV), hepatitis B and C, and syphilis.
Universal Genetic Carrier Screening: This optional test identifies whether or not you carry genes for particular genetic disorders, which might be passed to the fetus.
Ovarian reserve testing: Tests the number of oocytes (eggs) available in your ovaries, which decreases with age. Blood hormone tests include anti-Mullerian hormone (AMH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol levels.
Semen analysis: Measures the quality and quantity of sperm.
Uterine imaging: This might include a transvaginal ultrasound, hysterosalpingogram or HSG (an X-ray of your uterus and fallopian tubes), or a hysteroscopy (viewing your uterus by inserting a thin telescope through your cervix).
Transvaginal Ultrasound
A transvaginal ultrasound is an imaging test where the provider inserts a small wand (about the size of a tampon) into the vagina to view female reproductive organs using sound waves. It may be mildly uncomfortable—similar to getting a pelvic exam or pap smear—but it is not painful.
You may also take oral contraceptives (birth control pills) for the month before beginning an IVF cycle. This can help you start the IVF process at the ideal time and prevent natural ovulation.
Ovarian Stimulation
The first day of menstrual bleeding is considered the first day of an IVF cycle. On day two or three, you will likely have a transvaginal ultrasound, as well as blood testing to check hormone levels. If everything looks normal, you will begin the ovarian stimulation phase. This phase includes 8-14 days of prescription medications that help your ovaries produce multiple eggs.
During this stage, the reproductive endocrinologist periodically checks the progress of follicle development (sacs in the ovaries that contain eggs) and hormone levels through transvaginal ultrasounds and blood tests. This might require you to go to the fertility center every few days, or even daily at times.
When the eggs are mature, you'll receive an injection of a hormone called human chorionic gonadotropin (hCG). You will need to do this injection at a very specific time, usually in the evening. The egg retrieval will take place about 34-36 hours after the injection, or "trigger shot."
If you use an egg donor, the donor will follow the process above. If you plan on carrying the embryo, you will take hormonal medications that help prepare your uterus for pregnancy.
Egg Retrieval and Sperm Sample
The egg retrieval takes place at the fertility center or a nearby hospital. You'll change into a hospital gown and be brought into an operating room when it's time for the procedure.
During egg retrieval, the reproductive endocrinologist inserts a thin needle into your ovaries through your vaginal wall and gently suctions the eggs out through the needle. If your ovaries are hard to reach, your RE may retrieve your eggs abdominally. This typically occurs under sedation to ensure your comfort.
Sedation
Sedation for IVF typically involves an intravenous (IV) medication called propofol that puts you in a deep sleep. It is not the same type of anesthesia used for surgery, and, therefore, does not require the use of a breathing tube. An anesthesiologist—a medical doctor who specializes in anesthesia and pain management—will administer it. When administered properly you won't feel pain or be alert during the procedure.
The egg retrieval procedure takes about 30 minutes. After the procedure, you will go to a recovery room where nurses will monitor you as you wake up from sedation. That day or the following day, someone from the fertility clinic will let you know how many mature eggs were retrieved.
Most people go home after recovering for at least 45 minutes. Your RE will likely advise you to relax and avoid strenuous activities for at least 24 hours and possibly a few days after retrieval. Some REs prescribe antibiotics during this time.
You may experience mild cramping or discomfort similar to period cramps. Call your RE if you experience severe pain or symptoms like:
Severe bleeding
Sperm collection–outside of donor conception, using frozen samples, or surgical sperm retrieval–typically occurs on the day of egg retrieval.
Follow the RE's instructions when providing the sperm sample. For example, you might be instructed to not ejaculate for several days beforehand.
Related: How Much It Costs to Store Sperm and When To Do It
Fertilization
The next step is fertilization. Specialists combine the eggs and sperm in a laboratory (petri) dish to create embryos. In conventional insemination, they combine the eggs and sperm in a petri dish where they fertilize naturally.
Intracytoplasmic sperm injection (ICSI) is a technique that can help increase the likelihood of fertilization. Specialists use a needle to inject a single live sperm directly into a mature egg. ICSI might be used in the case of abnormal sperm or if conventional insemination does not work. About 60% of cycles in the United States uses this method.
In general, about 65% of eggs fertilize. Someone from the fertility clinic will let you know how many eggs fertilized successfully.
Embryo Development
The fertilized eggs divide and become embryos. The embryos are kept in a controlled lab environment as they develop and grow.
Here is the basic timeline, based on the number of days after egg retrieval:
Day 2: This is the beginning of the cleavage (cell division) stage. The embryo contains 2-4 cells.
Day 3: The embryo contains 6-10 cells.
Day 5: The embryo is now a blastocyst. It contains at least 60-100 cells. The placenta and fetal tissues start to separate, and a fluid-filled cavity forms within the embryo. Some embryos develop a bit slower, so your clinic may let them continue to culture until day six or seven. You cannot do a fresh transfer of a day six or seven embryo.
Natural attrition occurs between egg retrieval and the blastocyst stage. In other words, not all of your eggs will fertilize, and not all fertilized eggs will mature into embryos. Most of the loss occurs during embryo development. Up to 50% of fertilized eggs make it to the blastocyst stage, and the likelihood decreases with age.
Genetic Testing of Embryos
You may choose to do genetic testing for the embryos, which happens at the blastocyst stage. This might include:
Pre-implantation genetic testing for aneuploidy (PGT-A): Screens for chromosomal abnormalities. Embryos are normal (euploid), abnormal (aneuploid), or mosaic. Mosaic embryos have both normal and abnormal cells. Euploid embryos are the preferred embryo type, as they tend to have the highest pregnancy success rates. Some clinics will transfer mosaic embryos. Clinics typically will not transfer aneuploid embryos as those embryos often carry fatal genetic abnormalities.
Pre-implantation genetic testing for monogenic disease (PGT-M): Screens for one disease-specific gene or mutation. This is used when one parent has an illness or both parents are carriers for a genetic condition. Typically those donating eggs and sperm undergo carrier screening, so If you carry a condition and are looking to conceive using your genetic material plus donor eggs or sperm, you can select a donor who isn't also a carrier.
Pre-implantation genetic testing can help you decide which embryo or embryos to implant. There is a risk of losing embryos during the process. It's important to understand all potential benefits and risks before deciding if genetic testing of embryos is right for you. If you choose to do genetic testing, you will also find out the sex of your embryos.
Jamie Wolff, Health Editor
"I chose to do Universal Genetic Carrier Screening and PGT-A because I wanted greater confidence in a healthy baby after going through a relatively longer fertility journey. I decided against more comprehensive screening as it was expensive, and it didn't seem as important in my particular situation."
Embryo Transfer
About 3-5 days after egg retrieval, the embryos are ready for transfer. One or two of the highest-quality fresh or frozen embryos will be transferred, depending on the fertility center and other factors. Freezing embryos allows more time for genetic testing before the transfer.
For the embryo transfer, you will lie on the exam table with your legs in stirrups. Here are the basic steps of the procedure:
The reproductive endocrinologist uses a speculum to open your vaginal canal (like during a pap smear).
They pass a long, thin tube through your vagina, past your cervix (uterus opening), and into your uterus.
They transfer the embryo or embryos into your uterus through the tube.
Embryo transfer does not require sedation. You will go home an hour or two later, after a brief period of monitoring. You will likely be able to return to normal activities, but your RE might encourage you to rest for at least a few hours.
The most current studies show that strict bed rest is unnecessary following an embryo transfer. Follow the guidelines from your RE and take time to rest, if possible. Consider distracting activities like reading, watching movies, or hobbies during this waiting period, as you may feel anxious, nervous, or excited.
Cryopreservation of Eggs or Embryos
You have the option of cryopreserving (freezing) eggs or embryos you don't plan to use immediately. You can use these eggs or embryos for future pregnancies or possibly for donation. They can be stored for as long as you'd like, though you'll likely need to pay for their storage.
Not all eggs and embryos survive the freezing and thawing process, and the live birth rate is lower with frozen embryos. However, cryopreservation is very safe and allows you greater flexibility in terms of when you choose to build your family.
Related: How Much It Costs to Store Sperm and When To Do It
Results
The goal of IVF is the creation of at least one embryo. From there, possible options include:
Transferring a fresh or frozen embryo, with the goal of pregnancy
Cryopreserving your embryos for the future
Using a gestational carrier
If you or a gestational carrier has an embryo transfer, a fertility specialist will perform a pregnancy test about 10 days after that. This test measures your hCG blood level and determines whether or not the embryo is implanted.
Someone from the clinic will call you to let you know if the result is positive or negative and give you instructions for further testing or consultations.
Interpreting Your Results
If you choose to transfer fresh or frozen embryos, you will take a pregnancy test in the fertility clinic 9-14 days after the transfer.
The interpretation of hCG levels is as follows:
First hCG <5 international units/L: Not pregnant
First hCG >10 international units/L: Most likely pregnant, but requires confirmation with a second test in 48 hours
Second hCG test (48 hours after the first test): If the level of hCG doubles, this indicates pregnancy. If it decreases, this may mean that the pregnancy is not developing as expected and may not progress.
If the pregnancy test is positive, your RE will schedule periodic blood work and ultrasounds to monitor the pregnancy's progress. You will need to take daily progesterone shots or pills for 8-12 weeks after the embryo transfer. Progesterone is a reproductive hormone that prepares the uterus for implantation and helps the embryo grow. It reduces the risk of miscarriage.
A biochemical pregnancy can occur if blood tests indicate a pregnancy based on hCG levels but they fail to continue rising. A clinical pregnancy is a pregnancy at six weeks that can be seen using ultrasound. Your RE will release you to an obstetrician 8-10 weeks into the pregnancy.
If the test is negative, communicate openly with your RE and explore options such as repeating IVF cycles or alternative fertility treatments. IVF can take multiple cycles to be successful, and sometimes using a donor can increase the likelihood of a successful pregnancy.
Success Rates
IVF live birth success rates depend on many factors. Age is the biggest factor if you use your own eggs. Other factors include underlying medical conditions and whether or not you use a donor egg, sperm, or embryo. In 2021, approximate IVF success rates for live births in the United States were as follows:
Under age 35: 45%
35-37: 32%
38-40: 21%
41-42: 10%
Over age 42: 3%
These are the general live birth rates for each in vitro fertilization cycle. The Society for Assisted Reproductive Technology (SART) has a "predict my success" calculator to help you estimate the probability of having a baby with one or more cycles of IVF.
Possible Risks
An IVF cycle is generally safe, but it comes with potential risks. These include:
Multiples: Implanting more than one embryo increases the possibility of multiple fetuses. This can lead to health risks for the pregnant person and fetuses.
Discomfort: Fertility medications can cause symptoms like abdominal pain, bloating, headaches, and mood swings.
Egg retrieval risks: Risks of the surgical procedure include bleeding, infection, and reaction to anesthesia.
Ovarian hyperstimulation syndrome (OHSS): Though rare, too much ovarian stimulation can cause a buildup of fluids in the chest and abdomen. This can lead to symptoms like bloating, nausea, rapid weight gain, and shortness of breath. Bed rest usually resolves minor OHSS, but more severe OHSS might require hospitalization.
Premature birth or low birth weight: Infants conceived through in vitro fertilization might have a higher risk of premature birth (birth before 36 weeks) or lower birth weight.
Ectopic pregnancy: An ectopic pregnancy is when the embryo implants outside the uterus. This is not a viable pregnancy, meaning the pregnancy cannot move forward. It can be dangerous for the pregnant person and requires emergency medical attention.
A Quick Review
In vitro fertilization (IVF) is a type of assistive reproductive technology (ART) where egg fertilization occurs in a laboratory. There are many reasons why someone might use IVF to build their family, including infertility or fertility preservation. It can also be a powerful family-building tool for same-sex couples or single parents looking to conceive through egg or sperm donation.
Not everyone successfully conceives using in vitro fertilization, and it might take several cycles for pregnancy to occur. However, it can be a hopeful alternative to natural conception.
Jamie Wolff, an editor at Health, who has an M.A. in clinical mental health counseling and expressive therapies. She went through IVF from 2019-2020 and believes in the power of sharing fertility journeys.
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