Assisted reproductive technology (ART) is a group of medical procedures that involve handling eggs and sperm outside the body to help achieve pregnancy. The most common form is in vitro fertilization (IVF), but the category also includes egg and embryo freezing, egg and embryo donation, and the use of gestational carriers. What ties all ART procedures together is that eggs are surgically removed from the ovaries, combined with sperm in a laboratory, and then transferred to a uterus.
How IVF Works, Step by Step
IVF follows a sequence that typically spans two to three weeks per cycle. It starts with ovarian stimulation, where hormone medications prompt the ovaries to produce multiple mature eggs instead of the single egg released in a normal menstrual cycle. A doctor monitors follicle growth with ultrasound and blood tests, then schedules the egg retrieval.
During retrieval, a needle is guided through the vagina into each follicle, and eggs are suctioned out. The procedure takes about 20 minutes under sedation. Those eggs go straight to the lab, where they’re combined with sperm. In standard IVF, sperm and eggs are placed together in a dish and fertilization happens on its own. In a variation called intracytoplasmic sperm injection (ICSI), a single sperm is injected directly into each mature egg. ICSI is typically used when sperm count or motility is low.
Over the next three to six days, embryologists watch the fertilized eggs develop. By day three, a healthy embryo contains roughly 6 to 10 cells. By day five or six, it reaches what’s called the blastocyst stage, a rapidly dividing ball of cells with an inner group that will eventually become the fetus. At that point, one or more embryos are placed into the uterus through a thin catheter, a quick procedure that usually doesn’t require sedation. Any remaining healthy embryos can be frozen for future use.
Surgical Sperm Retrieval
Some men produce sperm but can’t deliver it through ejaculation, often due to a prior vasectomy, a blockage, or a condition called azoospermia (the absence of sperm in the ejaculate). In these cases, sperm can be collected surgically for use with ICSI. The simplest method involves inserting a needle into the testicle or the epididymis (a small structure behind the testicle where sperm mature) and aspirating tissue containing sperm. For men who produce very little sperm, a more involved approach called microdissection uses a surgical microscope to locate pockets of sperm-producing tissue while removing as little testicular tissue as possible.
Genetic Testing of Embryos
Before an embryo is transferred, it can be screened for genetic problems. This is done by removing a small sample of about 5 to 10 cells from the outer layer of the blastocyst, the part that will become the placenta rather than the fetus itself.
There are three main types of testing. The broadest, called PGT-A, screens all 23 pairs of chromosomes for missing or extra copies. Having the wrong number of chromosomes is the most common reason embryos fail to implant or end in early miscarriage, so PGT-A aims to identify the embryos most likely to result in a healthy pregnancy. A second type, PGT-M, looks for a specific genetic mutation that runs in a family, such as the genes responsible for cystic fibrosis, Huntington disease, or hereditary cancer syndromes like BRCA-related breast and ovarian cancer. The third, PGT-SR, is used when a parent carries a structural chromosome rearrangement that could cause gains or losses of genetic material in the embryo.
PGT-M can also be used in a more specialized way: identifying embryos that are both unaffected by a genetic disease and a tissue match for a sick sibling who needs a bone marrow transplant or cord blood transfusion.
Third-Party Reproduction
ART doesn’t require that the intended parents supply their own eggs, sperm, or uterus. Donor eggs are commonly used when a woman’s own eggs are unlikely to produce a viable pregnancy, whether due to age, premature ovarian insufficiency, or genetic concerns. Donor sperm is an option for single women, same-sex female couples, or couples facing severe male infertility. Donated embryos, often from other couples who completed their families through IVF, offer another path.
A gestational carrier (sometimes called a surrogate) is a person who carries a pregnancy for someone else. The embryo transferred to the carrier is created through IVF, so the carrier has no genetic connection to the child. This option is used by women who cannot safely carry a pregnancy, by single men, and by same-sex male couples.
Success Rates by Age
Age is the single strongest predictor of whether an ART cycle will result in a live birth, because egg quality declines over time. For women using their own eggs, live birth rates per egg retrieval follow a steep curve:
- Age 40: about 33%
- Age 42: about 24%
- Age 43: about 17%
- Age 44: about 11%
- Age 45 and older: roughly 6% or lower, dropping to 0% by age 48
For younger patients, success rates are considerably higher. Among women under 35 who had genetically screened embryos transferred one at a time (the current standard approach), live birth rates per transfer reach about 55%. Genetic screening levels the playing field somewhat for older patients: women aged 41 to 42 using screened embryos see per-transfer live birth rates near 50%, because only chromosomally normal embryos are selected. The challenge is that older patients produce fewer normal embryos per cycle, so multiple retrievals may be needed.
Single Versus Multiple Embryo Transfer
One of the biggest shifts in ART over the past decade is the move toward transferring a single embryo at a time rather than two or three. Twin and higher-order pregnancies carry significantly higher risks of preterm birth, low birth weight, and complications for both the parent and the babies. For women under 35, about 88% of fresh transfers now involve a single embryo. When genetic screening is used, the single-embryo rate climbs above 96% across all age groups.
The tradeoff is modest. For women under 35 using fresh embryos without genetic screening, live birth rates are actually slightly higher with a single transfer (44%) than with multiple embryos (39%), likely because the best-quality embryo is selected. In older age groups, transferring more than one embryo does boost per-cycle success rates somewhat, but the added pregnancy risks generally push clinicians toward one embryo at a time when a genetically screened embryo is available.
Risks and Complications
Serious short-term complications from ART procedures occur in roughly 2% of cycles. The most common is ovarian hyperstimulation syndrome (OHSS), which accounts for about half of all complications. OHSS happens when the ovaries overreact to the hormones used during stimulation, causing them to swell and leak fluid into the abdomen. Mild cases involve bloating and discomfort that resolve on their own. Severe cases, which are rare, can cause rapid weight gain, difficulty breathing, blood clots, and in extreme instances can be life-threatening.
Other uncommon risks include bleeding or infection from the egg retrieval procedure, and ovarian torsion (twisting of the ovary), which is often associated with the swollen ovaries of OHSS. Modern protocols that use lower hormone doses and trigger ovulation with different medications have reduced the incidence of severe OHSS significantly compared to earlier years of IVF.
Cost and Insurance Coverage
A single IVF cycle in the United States typically costs between $15,000 and $20,000. Cycles involving donor eggs can exceed $30,000. These figures cover medications, monitoring, retrieval, and transfer, but add-ons like genetic testing, embryo freezing, and annual storage fees increase the total. Many patients need more than one cycle, so cumulative costs can climb quickly.
Insurance coverage varies dramatically by state. Twenty-nine states do not require private insurers to cover IVF at all, leaving patients in those states to pay entirely out of pocket or seek employer-sponsored fertility benefits, which have become more common in recent years but remain far from universal. In states that do mandate coverage, the specifics differ: some require insurers to offer IVF coverage, others require them to cover it outright, and most set limits on the number of cycles or the patient’s age.