Science gives life most literally in the fertility clinic, where eggs and sperm meet in a lab dish, embryos grow in temperature-controlled incubators, and pregnancies begin outside the human body. In vitro fertilization and its surrounding technologies have produced more than 12 million babies worldwide since 1978. The field continues to evolve rapidly, with artificial intelligence now helping select the most viable embryos and cryopreservation techniques pushing egg survival rates above 90%.
How IVF Works, Step by Step
A single IVF cycle moves through five stages over roughly four to six weeks. It begins with ovarian stimulation: daily hormone injections over 9 to 15 days that prompt the ovaries to produce multiple eggs instead of the usual one per month. During this phase, ultrasounds and blood tests track how the eggs are developing.
Once the eggs are mature, a short outpatient procedure called egg retrieval removes them. A thin needle, guided by ultrasound, passes through the vaginal wall into each ovary and suctions eggs from their follicles one at a time. Most people experience mild cramping that resolves within a day.
In the lab, sperm and eggs are combined in a controlled chamber. Fertilization typically happens within a few hours. When the odds of natural fertilization are low, a single sperm can be injected directly into the egg, a technique many clinics now use routinely. The resulting embryos are cultured for five to seven days, growing from a single fertilized cell to a blastocyst of several hundred cells. Embryologists evaluate quality at each stage before the best embryo is transferred to the uterus through a thin catheter.
Success Rates by Age
Age is the single most important factor in IVF outcomes. National data from the Society for Assisted Reproductive Technology (2022) shows live birth rates per intended egg retrieval using a patient’s own eggs:
- Under 35: 53.5% live birth rate
- 35 to 37: 39.8%
- 38 to 40: 25.6%
These numbers represent the realistic chance of taking home a baby from a single retrieval cycle, including cases where embryos are frozen and transferred later. The steep decline after 37 reflects the natural loss of egg quality and quantity that accelerates in the late thirties.
Freezing Eggs and Embryos
Modern vitrification, an ultra-rapid freezing method, has transformed fertility preservation. Older slow-freeze techniques damaged a significant percentage of eggs through ice crystal formation. Current vitrification protocols achieve survival rates above 90% after thawing, with fertilization rates above 75% and pregnancy rates of 32 to 65% per embryo transfer, numbers that approach those of fresh eggs.
This leap in reliability is what makes elective egg freezing a viable option for people who want to delay childbearing. It also allows clinics to freeze all embryos from a retrieval cycle and transfer them one at a time in later months, reducing the risk of twins or triplets while maximizing the chances from each retrieval.
Genetic Screening Before Transfer
Preimplantation genetic testing for aneuploidy, known as PGT-A, screens embryos for the wrong number of chromosomes before transfer. Chromosomal errors are the leading cause of failed implantation and early miscarriage, and they become more common with age.
The process involves removing a few cells from the outer layer of the blastocyst on day five or six and analyzing them. A large meta-analysis found PGT-A has a diagnostic accuracy (measured by area under the curve) of about 0.81, meaning it catches most chromosomally abnormal embryos but isn’t perfect. It performs better in women over 38, where abnormal embryos are more common and screening has the most clinical value. The test adds cost and isn’t universally recommended for younger patients with plenty of normal embryos, but for people with recurrent miscarriage or repeated implantation failure, it can meaningfully shorten the path to a healthy pregnancy.
AI in the Embryology Lab
Choosing which embryo to transfer has traditionally relied on an embryologist’s visual assessment of shape, cell division speed, and overall appearance. Artificial intelligence is beginning to change that. AI systems trained on thousands of embryo images can now predict implantation success with measurable, if still modest, improvements over human grading alone.
One system called FiTTE, which combines blastocyst images with patient clinical data, achieved a 62.7% improvement in prediction accuracy over traditional grading methods. Another tool, the Life Whisperer, analyzed nearly 9,000 embryos and predicted clinical pregnancy with about 64% accuracy and a sensitivity of 70%. These numbers don’t sound dramatic, but in a field where every percentage point translates to fewer failed transfers and less emotional and financial cost, they matter.
A separate AI model that incorporates time-lapse imaging, which captures embryo development in continuous video rather than snapshots, reached 88% accuracy in predicting whether a blastocyst was chromosomally normal. Time-lapse monitoring is non-invasive, meaning it evaluates embryos without removing any cells, potentially reducing the need for biopsy-based genetic testing in the future.
What IVF Actually Costs
In the United States, the all-in cost of one IVF cycle typically falls between $19,000 and $30,000. That figure includes the clinic’s fees for monitoring, retrieval, and transfer, plus medications that alone run $2,000 to $7,000 per cycle. Genetic testing adds another $4,000 to $5,000 nationally, and a frozen embryo transfer in a later cycle averages around $6,000.
Some lower-cost clinics offer complete cycles for $7,000 to $12,000, though location and travel costs factor in. Insurance coverage varies widely. Many plans cover diagnostic testing and bloodwork but exclude the IVF procedure itself. Even with coverage, deductibles and copays mean most patients pay significant amounts out of pocket. Since many people need more than one cycle, the cumulative cost often reaches $40,000 to $60,000 before a successful pregnancy.
The Next Frontier: Making Eggs From Skin Cells
The most transformative technology on the horizon is in vitro gametogenesis, or IVG: the ability to create functional eggs or sperm from a person’s own skin or blood cells. In mice, researchers have already completed this process from start to finish. Skin cells were reprogrammed into stem cells, then coaxed into becoming eggs, which were fertilized and produced live, fertile offspring.
In humans, scientists have reached early stages of this process, successfully generating precursors to egg and sperm cells from stem cells. But the full journey from skin cell to functional human egg remains incomplete. Ethical guidelines from the International Society for Stem Cell Research currently prohibit applying IVG to human reproduction, though research continues under specialized oversight.
If IVG eventually works in humans, it would reshape fertility medicine fundamentally. People who don’t produce their own eggs or sperm, including those who lost fertility to cancer treatment, could have biological children. Same-sex couples could have a child genetically related to both parents. Transgender individuals could produce gametes matching their gender identity. And for anyone undergoing fertility treatment, IVG could eliminate egg retrieval entirely, replacing a physically demanding and expensive procedure with a simple blood draw or skin biopsy. That possibility alone, participants in one stakeholder study noted, would remove what many described as the most harrowing part of the IVF process.