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categories: ["reproduction", "society"]categories: ["reproduction", "society"]tags: ["reproduction", "ivf", "embryo selection", "fertility", "regulation", "bioethics"]tags: ["reproduction", "ivf", "embryo selection", "fertility", "regulation", "bioethics"]summary: "The routine clinical procedure in which eggs are fertilised outside the body and an embryo is transferred to a uterus, and the platform every other embryo technology is built on."summary: "The routine clinical procedure in which eggs are fertilised outside the body and an embryo is transferred to a uterus, and the platform every other embryo technology is built on."updated: "2026-07-28"updated: "2026-10-29"humanEvidence: "Between ten and thirteen million children had been born after assisted reproduction by 2018 and several million since; live-birth rates fall steeply with the age of the egg, and birth defects are modestly more common than after natural conception."humanEvidence: "Between ten and thirteen million children had been born after assisted reproduction by 2018 and several million since; live-birth rates fall steeply with the age of the egg, and birth defects are modestly more common than after natural conception."access: "Available in most countries with a fertility sector but funded unevenly: NHS-funded cycles fell from 35 percent of UK treatments in 2019 to 27 percent in 2023, and a self-funded cycle costs several thousand pounds or dollars before optional extras."access: "Available in most countries with a fertility sector but funded unevenly: NHS-funded cycles fell from 35 percent of UK treatments in 2019 to 27 percent in 2023, and a self-funded cycle costs several thousand pounds or dollars before optional extras."reversibility: "irreversible"reversibility: "irreversible"lines 22–28 → 22–287 unchanged lines not shown
{ "label": "First live birth", "value": "1978, Oldham, England" }, { "label": "First live birth", "value": "1978, Oldham, England" }, { "label": "Developed by", "value": "Robert Edwards, Patrick Steptoe" }, { "label": "Developed by", "value": "Robert Edwards, Patrick Steptoe" }, { "label": "Nobel Prize", "value": "Medicine, 2010" }, { "label": "Nobel Prize", "value": "Medicine, 2010" }, { "label": "Children born", "value": "10–13 million by 2018" }, { "label": "Children born", "value": "10-13 million by 2018" }, { "label": "Share of UK births", "value": "1 in 32 (2023)" }, { "label": "Share of UK births", "value": "1 in 32 (2023)" }, { "label": "Key variants", "value": "ICSI, frozen transfer, PGT" }, { "label": "Key variants", "value": "ICSI, frozen transfer, PGT" }, { "label": "UK regulator", "value": "HFEA" } { "label": "UK regulator", "value": "HFEA" }lines 30–42 → 30–421 unchanged line not shown
}}`````` **In vitro fertilisation** is the procedure in which eggs are recovered from ovaries, combined with sperm in a laboratory dish, cultured for a few days, and transferred to a uterus as an embryo. It is the oldest and most-performed of the assisted reproductive technologies, and it matters far beyond infertility medicine: almost every technique this wiki covers under reproduction, from [[embryo-selection]] to [[germline-editing]], is an operation performed on an embryo that only exists because of IVF.**In vitro fertilisation** is the procedure in which eggs are recovered from ovaries, combined with sperm in a laboratory dish, cultured for a few days, and transferred to a uterus as an embryo. It is the oldest and most widely performed of the assisted reproductive technologies, and its reach extends far beyond infertility medicine. Almost every technique this wiki covers under reproduction, from [[embryo-selection]] to [[germline-editing]], is an operation on an embryo that exists only because of IVF. ## How a cycle works## How a cycle works A cycle runs in four steps: stimulation, egg collection, fertilisation and culture, transfer. Injected gonadotrophins stimulate the ovaries to mature many follicles at once rather than the single one of a natural cycle; ultrasound and blood hormone measurements track the response; and eggs are collected under sedation by a needle passed through the vaginal wall. In the laboratory the eggs are either mixed with prepared sperm, or, where sperm quality is poor, injected one sperm per egg by intracytoplasmic sperm injection. Fertilised eggs are cultured for two to six days, usually to the blastocyst stage. One embryo is transferred; the rest are vitrified and stored.A cycle runs in four steps: stimulation, egg collection, fertilisation and culture, transfer. Injected gonadotrophins stimulate the ovaries to mature many follicles at once, where a natural cycle matures one. Ultrasound and blood hormone measurements track the response, and eggs are collected under sedation by a needle passed through the vaginal wall. In the laboratory the eggs are either mixed with prepared sperm or, where sperm quality is poor, injected with one sperm each by intracytoplasmic sperm injection (ICSI). Fertilised eggs are cultured for two to six days, usually to the blastocyst stage. One embryo is transferred; the rest are vitrified and stored. Two changes have reshaped that sequence since the 1990s. ICSI, first reported by a Brussels group in 1992, made severe male-factor infertility treatable and is now used in a majority of cycles worldwide, including many where the indication for it is unclear.[^palermo1992] Vitrification, an ultra-rapid cooling method that avoids ice crystal formation, made frozen embryo and egg storage reliable enough that transferring a thawed embryo in a later cycle is now often preferred to transferring a fresh one. It is the same physical principle that [[cryonics]] proposes to apply to a whole body, working here on a hundred-micrometre object with no vasculature.Two changes have reshaped that sequence since the 1990s. ICSI, first reported by a Brussels group in 1992, made severe male-factor infertility treatable and is now used in a majority of cycles worldwide, including many where the indication for it is unclear.[^palermo1992] Vitrification, an ultra-rapid cooling method that avoids ice crystal formation, made frozen embryo and egg storage reliable enough that transferring a thawed embryo in a later cycle is now often preferred to transferring a fresh one. [[cryonics]] proposes to apply the same physical principle to a whole body; in IVF it works on a hundred-micrometre object with no vasculature. ## Development history## Development history lines 45–51 → 45–512 unchanged lines not shown
{ "year": "1959", "title": "Rabbit IVF confirmed", "text": "Min Chueh Chang produces live rabbit young from eggs fertilised in vitro, establishing that mammalian fertilisation outside the body can yield normal offspring." }, { "year": "1959", "title": "Rabbit IVF confirmed", "text": "Min Chueh Chang produces live rabbit young from eggs fertilised in vitro, establishing that mammalian fertilisation outside the body can yield normal offspring." }, { "year": "1978", "title": "Louise Brown", "text": "Patrick Steptoe and Robert Edwards report the first human birth after in vitro fertilisation, achieved in an unstimulated cycle with a single egg." }, { "year": "1978", "title": "Louise Brown", "text": "Patrick Steptoe and Robert Edwards report the first human birth after in vitro fertilisation, achieved in an unstimulated cycle with a single egg." }, { "year": "1990", "title": "Preimplantation testing", "text": "Alan Handyside's group biopsies human embryos and selects by sex to avoid X-linked disease, opening the field of embryo testing." }, { "year": "1990", "title": "Preimplantation testing", "text": "Alan Handyside's group biopsies human embryos and selects by sex to avoid X-linked disease, opening the field of embryo testing." }, { "year": "1990–1991", "title": "Statutory regulation in the UK", "text": "The Human Fertilisation and Embryology Act creates a licensing authority with a fourteen-day limit on embryo culture, the model most later regimes were measured against." }, { "year": "1990-1991", "title": "Statutory regulation in the UK", "text": "The Human Fertilisation and Embryology Act creates a licensing authority with a fourteen-day limit on embryo culture, the model most later regimes were measured against." }, { "year": "1992", "title": "ICSI", "text": "A single sperm injected directly into an egg produces pregnancies, extending treatment to men with almost no motile sperm." }, { "year": "1992", "title": "ICSI", "text": "A single sperm injected directly into an egg produces pregnancies, extending treatment to men with almost no motile sperm." }, { "year": "2010", "title": "Nobel Prize", "text": "Robert Edwards receives the Nobel Prize in Physiology or Medicine; Steptoe had died in 1988 and the prize is not awarded posthumously." }, { "year": "2010", "title": "Nobel Prize", "text": "Robert Edwards receives the Nobel Prize in Physiology or Medicine; Steptoe had died in 1988 and the prize is not awarded posthumously." }, { "year": "2012", "title": "Egg freezing leaves the experimental category", "text": "Vitrification results are judged good enough for the American Society for Reproductive Medicine to drop the experimental label from oocyte cryopreservation, and elective egg banking becomes a commercial market." } { "year": "2012", "title": "Egg freezing leaves the experimental category", "text": "Vitrification results are judged good enough for the American Society for Reproductive Medicine to drop the experimental label from oocyte cryopreservation, and elective egg banking becomes a commercial market." }lines 54–92 → 54–922 unchanged lines not shown
## What it delivers## What it delivers The dominant variable is the age of the egg, and success rates fall steeply through the late thirties and forties. They are also better described per patient across several cycles than per transfer, and a cumulative live-birth rate is the figure a well-run clinic will quote.The age of the egg is the dominant variable, and success rates fall steeply through the late thirties and forties. Success is also better described per patient across several cycles than per transfer, so a well-run clinic quotes a cumulative live-birth rate. Volume is now substantial. An analysis of four decades of international registry data put the number of children born after assisted reproduction between 1978 and 2018 at between roughly 9.8 and 13 million, with several million more since.[^adamson2025] UK licensed clinics ran more than 77,500 IVF cycles for 52,400 patients in 2023, producing almost 21,000 babies, about one UK birth in thirty-two; the multiple birth rate fell to 3.4% as single embryo transfer became standard.[^hfea2023] That last number is an underrated public-health result, because twin pregnancies carry much of the obstetric risk historically attributed to IVF itself.Volume is now substantial. An analysis of four decades of international registry data put the number of children born after assisted reproduction between 1978 and 2018 at between roughly 9.8 and 13 million, with several million more since.[^adamson2025] UK licensed clinics ran more than 77,500 IVF cycles for 52,400 patients in 2023, producing almost 21,000 babies, about one UK birth in thirty-two; the multiple birth rate fell to 3.4% as single embryo transfer became standard.[^hfea2023] The fall in multiple births is an underrated public-health result, because twin pregnancies carry much of the obstetric risk historically attributed to IVF itself. > [!key] Why this article sits in the middle of the reproduction portal> [!key] Why this article sits in the middle of the reproduction portal> Every embryo technology covered here operates on an embryo outside a body. [[polygenic-embryo-screening]] ranks embryos, [[mitochondrial-replacement-therapy]] rebuilds one, heritable editing would rewrite one, and [[in-vitro-gametogenesis]] would supply the eggs to make far more of them. None of those has an independent route to a pregnancy. IVF is the delivery mechanism for all of them, which is why its cost, its regulation, and the number of embryos a cycle yields set the practical limits on each.> Every embryo technology covered here operates on an embryo outside a body. [[polygenic-embryo-screening]] ranks embryos, [[mitochondrial-replacement-therapy]] rebuilds one, heritable editing would rewrite one, and [[in-vitro-gametogenesis]] would supply the eggs to make far more of them. None of them has an independent route to a pregnancy. IVF delivers all of them, so its cost, its regulation and the number of embryos a cycle yields set the practical limits on each. ## The platform other technologies stand on## The platform other technologies stand on Embryo biopsy and testing are the clearest case. Preimplantation genetic testing for monogenic disease is reliable and uncontroversial where a couple carries a known variant. Testing for aneuploidy is performed on a large share of cycles in some markets, and randomised trials have not shown that it raises live-birth rates per patient.[^munne2019] Polygenic screening extends the same biopsy to complex traits and is rejected as unvalidated by professional genetics bodies.Embryo biopsy and testing are the clearest case. Preimplantation genetic testing for monogenic disease is reliable and uncontroversial where a couple carries a known variant. Testing for aneuploidy is performed on a large share of cycles in some markets, and randomised trials have not shown that it raises live-birth rates per patient.[^munne2019] Polygenic screening extends the same biopsy to complex traits and is rejected as unvalidated by professional genetics bodies. Beyond selection, IVF is the necessary substrate for anything that edits or reconstructs an embryo. The [[he-jiankui-affair]] was carried out inside ordinary IVF cycles with ordinary equipment, using [[crispr-cas9]] reagents that can be ordered, which is the fact that makes [[governance-of-genome-editing|governance]] hard: the specialised part of heritable editing is a reagent, and the rest is a clinic that exists in most countries. In vitro gametogenesis, if it works in humans, would remove the binding constraint on embryo number and change what [[designer-babies|selection]] could deliver. Spare and donated embryos are also the starting material for human embryonic stem cell lines and for much of what is known about early human development, which is part of why [[induced-pluripotent-stem-cells|induced pluripotent stem cells]] and [[synthetic-embryos|embryo models]] were pursued at all: each reduces the dependence on donated embryos without removing it.Beyond selection, IVF is the necessary substrate for anything that edits or reconstructs an embryo. The [[he-jiankui-affair]] was carried out inside ordinary IVF cycles with ordinary equipment, using [[crispr-cas9]] reagents that can be ordered. That is what makes [[governance-of-genome-editing|governance]] hard: the specialised part of heritable editing is a reagent, and the rest is a clinic of the kind that exists in most countries. In vitro gametogenesis, if it works in humans, would remove the binding constraint on embryo number and change what [[designer-babies|selection]] could deliver. Spare and donated embryos are also the starting material for human embryonic stem cell lines and for much of what is known about early human development. That dependence is part of why [[induced-pluripotent-stem-cells|induced pluripotent stem cells]] and [[synthetic-embryos|embryo models]] were pursued at all; each reduces the need for donated embryos without removing it. ## Add-ons and the evidence problem## Add-ons and the evidence problem IVF is largely a private market even in countries with public health systems, and it sells optional extras: endometrial scratching, immunological treatments, time-lapse incubation, assisted hatching. The UK regulator rates these on a published scale and, at its 2023 overhaul, placed none of the thirteen it had reviewed in the category reserved for treatments shown by multiple good trials to improve live-birth rates.[^hfeaaddons] The scale itself has been criticised for compressing very different kinds of uncertainty into one colour, but the finding is not seriously disputed: patients pay for interventions that mostly have not been shown to work.IVF is largely a private market even in countries with public health systems, and it sells optional extras: endometrial scratching, immunological treatments, time-lapse incubation, assisted hatching. The UK regulator rates these on a published scale and, at its 2023 overhaul, placed none of the thirteen it had reviewed in the category reserved for treatments shown by multiple good trials to improve live-birth rates.[^hfeaaddons] The scale itself has been criticised for compressing very different kinds of uncertainty into one colour, but its central finding is not seriously disputed: patients pay for interventions that mostly have not been shown to work. > [!caution] What the success rate does not tell you> [!caution] What a success rate does not show> A clinic's headline rate depends on which patients it accepts and how it counts. Rates per embryo transferred exclude cycles cancelled before transfer; rates per cycle started include them. Neither figure describes an individual's chance, which is dominated by age and by cause of infertility.> A clinic's headline rate depends on which patients it accepts and how it counts. Rates per embryo transferred exclude cycles cancelled before transfer; rates per cycle started include them. Neither figure describes an individual's chance, which is dominated by age and by cause of infertility. ## Risks and outcomes for children## Risks and outcomes for children The ovarian stimulation itself carries a small risk of ovarian hyperstimulation syndrome, which has become less common with milder protocols and freeze-all strategies. Egg collection is a minor surgical procedure with the usual bleeding and infection risks.Ovarian stimulation carries a small risk of ovarian hyperstimulation syndrome, which has become less common with milder protocols and freeze-all strategies. Egg collection is a minor surgical procedure with the usual bleeding and infection risks. For the children, the honest summary is that risks are real, small, and hard to attribute. A systematic review and meta-analysis found birth defects modestly more common after assisted reproduction than after natural conception.[^hansen2013] Preterm birth and low birthweight are likewise somewhat more frequent. Whether that is caused by the laboratory procedures, by the underlying subfertility of the parents, or by the multiple pregnancies that were common in earlier practice has never been fully separated, and the same ambiguity attaches to the slightly raised rate of imprinting disorders. Follow-up now extends to adults in their forties without a signal that would change clinical practice.For the children, the risks are real but small, and hard to attribute to a cause. A systematic review and meta-analysis found birth defects modestly more common after assisted reproduction than after natural conception.[^hansen2013] Preterm birth and low birthweight are likewise somewhat more frequent. Nobody has fully separated the contributions of the laboratory procedures, the parents' underlying subfertility, and the multiple pregnancies that were common in earlier practice. The same ambiguity attaches to the slightly raised rate of imprinting disorders. Follow-up now extends to adults in their forties without a signal that would change clinical practice. ## Access, law and cost## Access, law and cost Regulation ranges from statute to nothing. The United Kingdom licenses clinics and specifies what may be tested for; several European states restrict embryo creation and storage tightly; the United States regulates laboratories and advertising but leaves the substance of practice to professional guidance. The gaps between these regimes drive reproductive travel, and they are the same gaps analysed under [[access-and-inequality]]. Where the law does bind, it binds oddly: the fourteen-day limit on embryo culture written into the UK statute in 1990 was set at a point nobody could then reach, and it is now the constraint the work described under [[ectogenesis]] and embryo modelling runs into.Regulation ranges from statute to nothing. The United Kingdom licenses clinics and specifies what may be tested for; several European states restrict embryo creation and storage tightly; the United States regulates laboratories and advertising but leaves the substance of practice to professional guidance. The gaps between these regimes drive reproductive travel, and they are the gaps analysed under [[access-and-inequality]]. Where the law does bind, it can bind in unexpected places. The fourteen-day limit on embryo culture written into the UK statute in 1990 was set at a point nobody could then reach, and it is now the constraint that the work described under [[ectogenesis]] and embryo modelling runs into. Funding is where the difference bites hardest. In the UK the NHS-funded share of cycles fell from 35% in 2019 to 27% in 2023, with wide regional variation.[^hfea2023] Elsewhere, cost is the binding constraint on who has children this way, and it compounds every downstream capability: a technology priced as an add-on to a self-funded cycle is available to the population that can already afford the cycle.Funding is where the differences matter most. In the UK the NHS-funded share of cycles fell from 35% in 2019 to 27% in 2023, with wide regional variation.[^hfea2023] Elsewhere, cost is the binding constraint on who has children this way, and it carries through to every downstream capability: a technology priced as an add-on to a self-funded cycle is available only to people who can already afford the cycle. Legal status of the embryo is unsettled in a way that can disrupt practice overnight. In February 2024 the Supreme Court of Alabama held that frozen embryos are children under the state's wrongful-death statute; several clinics suspended treatment, and the legislature passed immunity legislation within three weeks.[^lepage2024] The episode is the clearest recent demonstration that IVF's stability rests on a legal settlement about embryo status that is neither uniform nor secure, and that every technology built on top of it inherits that exposure.The legal status of the embryo is unsettled in a way that can disrupt practice overnight. In February 2024 the Supreme Court of Alabama held that frozen embryos are children under the state's wrongful-death statute; several clinics suspended treatment, and the legislature passed immunity legislation within three weeks.[^lepage2024] The episode is the clearest recent demonstration that IVF's stability rests on a legal settlement about embryo status that is neither uniform nor secure. Every technology built on top of IVF inherits that exposure. ## See also## See also removed, struck through added, underlinedLine numbers count the serialised markdown of each revision, frontmatter included.
94 lines are the same in both revisions, and 38 of them are not shown. Neither revision here is necessarily the current article — read In vitro fertilisation for the text this wiki stands behind today.