In vitro fertilization (IVF) is a fertility treatment where an egg and sperm are combined in a laboratory, and the resulting embryo is transferred into the uterus. “In vitro” literally means “outside the body,” distinguishing it from natural conception that happens inside the fallopian tubes. IVF is the most common and effective form of assisted reproduction, used to treat a wide range of infertility causes.
Who IVF Is For
IVF was originally developed for women with blocked or damaged fallopian tubes, but it now treats nearly every major cause of infertility. Common reasons people turn to IVF include endometriosis, polycystic ovary syndrome (PCOS), low sperm count or other male factor infertility, unexplained infertility where no clear cause has been identified, and advanced maternal age. It’s also used when other, less intensive treatments like fertility medications or intrauterine insemination haven’t worked.
How a Cycle Works, Step by Step
A full IVF cycle takes roughly four to six weeks from start to pregnancy test. Here’s what each phase looks like.
Ovarian Stimulation
Normally, your ovaries release one egg per menstrual cycle. IVF uses injectable hormone medications to push the ovaries to mature multiple eggs at once, giving the lab more to work with. These daily injections typically last eight days to two weeks. During this time, you’ll have frequent ultrasounds and blood draws so your care team can track how the eggs are developing and adjust your medication.
The hormones used are versions of chemicals your body already produces to regulate egg growth. The goal is a careful balance: enough stimulation to produce a good number of eggs, but not so much that you develop complications.
Egg Retrieval and Sperm Collection
Once the eggs are mature, they’re collected in a short procedure done under sedation. A thin needle guided by ultrasound passes through the vaginal wall to reach the ovaries. Most people go home the same day. Sperm is collected on the same day, either from a partner or a donor.
Fertilization
In the lab, there are two main ways to bring egg and sperm together. In conventional IVF, sperm are placed in a dish with the egg and fertilization happens on its own. In a technique called ICSI (intracytoplasmic sperm injection), a single sperm is injected directly into the egg. ICSI was originally developed for male factor infertility, particularly when sperm count or motility is low, but its use has expanded dramatically. It roughly halves the risk of total fertilization failure compared to conventional methods, even in couples without a male factor diagnosis.
Embryo Development
Fertilized eggs are monitored in the lab over the next several days. The embryology team checks development on days two and three. The target is for embryos to reach what’s called the blastocyst stage, typically five days after fertilization, though some embryos develop more slowly and reach this point on day six or seven. Not all fertilized eggs will make it to this stage.
Embryo Transfer
Transfer day is quick and typically painless, requiring no anesthesia. A thin catheter delivers the embryo through the cervix into the uterus. Current guidelines from the American Society for Reproductive Medicine strongly encourage transferring a single embryo to reduce the risk of twins or triplets, which carry higher risks for both mother and babies. The number has been trending downward for years as lab techniques have improved.
Twelve days after transfer, a blood test confirms whether pregnancy has begun.
Fresh vs. Frozen Embryo Transfer
Any embryos that aren’t transferred right away can be frozen (cryopreserved) for future use. You can also choose to freeze all embryos from a cycle and transfer one in a later month. This “freeze all” approach has become increasingly popular, and the data supports it.
In one large study comparing over 1,600 fresh transfers to over 1,200 frozen transfers, frozen embryo transfers had significantly better outcomes across the board. The clinical pregnancy rate was 47% with frozen embryos versus 35% with fresh. Live birth rates were also substantially higher in the frozen group. Frozen transfers were associated with lower rates of multiple pregnancy, first-trimester miscarriage, preterm delivery, and low birth weight. Babies born from frozen transfers also had a higher average birth weight (3.2 kg vs. 2.8 kg).
The likely reason: after weeks of ovarian stimulation, the uterine lining may not be in its most receptive state. Waiting a cycle allows your body to recover before the embryo is placed.
Genetic Testing of Embryos
Before transfer, embryos can be screened for genetic or chromosomal problems. A few cells are biopsied from the outer layer of the blastocyst and analyzed while the embryo is frozen. There are three main types of testing.
- PGT-A screens for the wrong number of chromosomes (aneuploidy), which is the leading cause of miscarriage and failed implantation. This is the most commonly used form, especially for people over 35 or those with recurrent pregnancy loss.
- PGT-M tests for specific inherited diseases like cystic fibrosis, sickle cell disease, Huntington’s disease, or BRCA-related cancer predisposition. It’s used when one or both parents carry a known genetic mutation.
- PGT-SR identifies structural chromosome rearrangements like translocations or deletions that could lead to miscarriage or developmental problems.
Genetic testing adds cost and an extra step to the process, but for many people it provides peace of mind and can reduce the number of transfers needed to achieve a healthy pregnancy.
Risks and Side Effects
The most significant risk specific to IVF is ovarian hyperstimulation syndrome (OHSS), caused by the ovaries overreacting to stimulation medications. A mild form is relatively common and typically resolves within a week. Symptoms include bloating, mild abdominal pain, nausea, and tenderness around the ovaries.
Severe OHSS is less common but requires close monitoring. Warning signs include rapid weight gain (more than about two pounds in 24 hours), severe nausea and vomiting, shortness of breath, significantly decreased urination, and a noticeably tight or enlarged abdomen. Blood clots are a rare but serious complication. Newer stimulation protocols using certain types of medications have significantly reduced the rate of severe OHSS compared to older approaches.
The egg retrieval itself carries small risks of bleeding, infection, or injury to surrounding structures, but serious complications are uncommon. Emotionally, IVF can be demanding. The combination of daily injections, frequent appointments, hormonal fluctuations, and the uncertainty of the outcome takes a real toll on many people.
What IVF Costs
In the United States, the base cost of a single IVF cycle falls between $14,000 and $20,000. Medications alone typically add another $3,000 to $6,000 per cycle on top of that. These figures don’t include extras like genetic testing, embryo freezing and annual storage fees, or frozen embryo transfer cycles, each of which adds to the total.
Insurance coverage varies enormously. Some states mandate fertility coverage, while in others IVF is entirely out of pocket. Many clinics offer payment plans, and some organizations provide grants for people who can’t afford treatment. Since not every cycle results in pregnancy, many people go through more than one, making the cumulative cost a significant factor in decision-making.