Everything about In Vitro Fertilization totally explained
In vitro fertilisation (
IVF) is a technique in which
egg cells are
fertilised by
sperm outside the woman's womb,
in vitro. IVF is a major treatment in
infertility when other methods of
assisted reproductive technology have failed. The process involves hormonally controlling the ovulatory process, removing
ova (eggs) from the woman's
ovaries and letting
sperm fertilise them in a fluid medium. The fertilised egg (
zygote) is then transferred to the patient's
uterus with the intent to establish a successful pregnancy.
"In vitro"
The term
in vitro, from the
Latin root meaning
in glass, is used, because early biological experiments involving cultivation of tissues outside the living organism from which they came, were carried out in glass containers such as
beakers, test tubes, or petri dishes. Today, the term
in vitro is used to refer to any biological procedure that's performed outside the organism it would normally be occurring in, to distinguish it from an
in vivo procedure, where the tissue remains inside the living organism within which it's normally found. A colloquial term for babies conceived as the result of IVF,
test tube babies, refers to the tube-shaped containers of glass or plastic resin, called
test tubes, that are commonly used in chemistry labs and biology labs. However
in vitro fertilisation is usually performed in the shallower containers called
petri dishes. (Petri-dishes may also be made of plastic
resins.) However, the IVF method of
Autologous Endometrial Coculture is actually performed on organic material, but is yet called
in vitro.
History
On the basis of the findings of
Min Chueh Chang's application of
in vitro fertilization to animals, the technique was developed for humans in the
United Kingdom by
Patrick Steptoe and
Robert Edwards. The first "test-tube baby",
Louise Brown, was born in
Oldham,
Greater Manchester,
England, as a result on
July 25,
1978 amid intense controversy over the safety and morality of the procedure.
Subhash Mukhopadhyay became the first physician in
India, and the second in the world after Steptoe and Edwards, to perform
the procedure and produce the test tube baby "Durga" (alias
Kanupriya Agarwal) on
October 3 1978. Facing social ostracism, bureaucratic negligence, reprimand and insult instead of recognition from the
Marxist West Bengal government and refusal of the Government of India to allow him to attend international conferences, Mukhopadhyay committed suicide in his
Calcutta residence in 1981.
Major pioneering developments in IVF also occurred in
Australia under the leadership of
Carl Wood,
Alan Trounson and
Ian Johnston.
The world's third IVF baby,
Candice Reed was born on
June 23,
1980 in
Melbourne,
Australia.
The first successful IVF treatment in the
USA (producing
Elizabeth Jordan Carr) took place in 1981 under the direction of Doctors Howard Jones and
Georgeanna Seegar Jones in
Norfolk,
Virginia. Since then IVF has exploded in popularity, with as many as 1% of all births now being conceived in-vitro, with over 115,000 born in the USA to date. At present, the percentage of children born after IVF (including with
intracytoplasmic sperm injection (ICSI)) has been up to 4% of all babies born in
Denmark.
Jane Mohr of Manhattan Beach California, gave birth to the nation's first set of triplets born 21 months apart due to
in vitro fertilisation (IVF) and long-term embryo storage. Jane gave birth November 29, 1988 to two daughters, Mollie McKenna and Hannah Christina Mohr, nearly two years after the birth of her son, Cooper Patrick Mohr.
Indications
Initially IVF was developed to overcome
infertility due to problems of the
fallopian tube, but it turned out that it was successful in many other infertility situations as well. The introduction of
intracytoplasmic sperm injection (ICSI) addresses the problem of male infertility to a large extent.
Thus, for IVF to be successful it may be easier to say that it requires healthy ova, sperm that can fertilise, and a uterus that can maintain a
pregnancy. Cost considerations generally place IVF as a treatment when other less expensive options have failed.
This means that IVF can be used for females who have already gone through pregnancy. The donated oocyte can be fertilised in a
crucible. If the fertilisation is successful, the fertilised egg will be transferred into the uterus, within which it'll develop into an embryo.
Method
Ovarian stimulation
Treatment cycles are typically started on the third day of
menstruation and consist of a regimen of fertility medications to stimulate the development of multiple
follicles of the ovaries. In most patients injectable
gonadotropins (usually
FSH analogues) are used under close monitoring. Such monitoring frequently checks the
estradiol level and, by means of
gynecologic ultrasonography, follicular growth. Typically approximately 10 days of injections will be necessary. Spontanenous ovulation during the cycle is prevented by the use of
GnRH agonists or GnRH antagonists, which block the natural surge of
luteinizing hormone (LH).
Oocyte retrieval
When follicular maturation is judged to be adequate,
human chorionic gonadotropin (β-hCG) is given. This agent, which acts as an analogue of
luteinizing hormone, would cause ovulation about 36 hours after injection, but a retrieval procedure takes place just prior to that, in order to recover the egg cells from the ovary. The eggs are retrieved from the patient using a transvaginal technique involving an ultrasound-guided needle piercing the vaginal wall to reach the ovaries. Through this needle follicles can be aspirated, and the follicular fluid is handed to the IVF laboratory to identify ova. The retrieval procedure takes about 20 minutes and is usually done under
conscious sedation or
general anesthesia.
Fertilisation
In the laboratory, the identified eggs are stripped of surrounding cells and prepared for fertilisation. In the meantime,
semen is prepared for fertilisation by removing inactive cells and seminal fluid. If semen is being provided by a sperm donor, it'll usually have been prepared for treatment before being frozen and quarantined, and it'll be thawed ready for use. The sperm and the egg are incubated together (at a ratio of about 75,000:1) in the
culture media for about 18 hours. By that time
fertilisation should have taken place and the fertilised egg would show two
pronuclei. In situations where the sperm count is low, a single sperm is injected directly into the egg using
intracytoplasmic sperm injection (ICSI). The fertilised egg is passed to a special growth medium and left for about 48 hours until the egg has reached the 6-8 cell stage.
(fat baby )
Selection
Laboratories have developed grading methods to judge oocyte and
embryo quality. Typically, embryos that have reached the 6-8 cell stage are transferred three days after retrieval. In many American and Australian programmes, however, embryos are placed into an extended culture system with a transfer done at the
blastocyst stage, especially if many good-quality day-3 embryos are available. Blastocyst stage transfers have been shown to result in higher pregnancy rates.. In Europe, day-2 transfers are common.
Embryo transfer
Embryos are graded by the embryologist based on the number of cells, evenness of growth and degree of fragmentation. The number to be transferred depends on the number available, the age of the woman and other health and diagnostic factors. In countries such as the UK, Australia and New Zealand, a maximum of two embryos are transferred except in unusual circumstances. For instance, a woman over 35 may have up to three embryos transferred. This is to limit the number of multiple pregnancies. The embryos judged to be the "best" are transferred to the patient's uterus through a thin, plastic
catheter, which goes through her
vagina and cervix. Several embryos may be passed into the uterus to improve chances of
implantation and
pregnancy.
Success rates
While the overall live birth rate via IVF in the U.S. is about 27% per cycle (33% pregnancy rate), the chances of a successful pregnancy via IVF vary widely based on the age of the woman (or, more precisely, on the age of the eggs involved).
(External Link
) Where the woman's own eggs are used as opposed to those of a donor, for women under 35, the pregnancy rate is commonly approximately 43% per cycle (36.5% live birth), while for women over 40, the rate falls drastically - to only 4% for women over 42.
(External Link) Other factors that determine success rates include the quality of the eggs and sperm, the duration of the infertility, the health of the uterus, and the medical expertise. It is a common practice for IVF programmes to boost the pregnancy rate by placing multiple embryos during embryo transfer. A flip side of this practice is a higher risk of
multiple pregnancy, itself associated with obstetric complications.
A recent technique is to bathe an embryo in a culture of nutrients for five days until it reaches a developmental landmark known as the blastocyst stage. The doctors then determine which embryos are most likely to thrive long term. The best quality of these are transferred into a woman's uterus. In this way it's possible to enable pregnancy without the risk of multiple pregnancy. This technique is relatively new and has yet to be well tested.
IVF programmes generally publish their pregnancy rates. However, comparisons between clinics are difficult as many variables determine outcome. Furthermore, these statistics depend strongly on the type of patients selected.
There are many reasons why pregnancy may not occur following IVF and embryo transfer, including
- The timing of ovulation may be misjudged, or ovulation may not be able to be predicted or may not occur
- Attempts to obtain eggs that develop during the monitored cycle may be unsuccessful
- The eggs obtained may be abnormal or may have been damaged during the retrieval process
- A semen specimen may not be able to be provided
- Fertilisation of eggs to form embryos may not occur
- Cleavage or cell division of the fertilised eggs may not take place
- The embryo may not develop normally
- Implantation may not occur
- Equipment failure, infection and/or human error or other unforeseen and uncontrollable factors, which may result in the loss of or damage to the eggs, the semen sample and/or the embryos
According to a 2005 Swedish study published in the Oxford Journal 'Human Reproduction' 166 women were monitored starting one month before their IVF cycles and the results showed no significant correlation between psychological stress and their IVF outcomes. The study concluded with the recommendation to clinics that it might be possible to reduce the stress experienced by IVF patients during the treatment procedure by informing them of those findings. While psychological stress experienced during a cycle might not influence an IVF outcome, it's possible that the experience of IVF can result in stress that leads to depression. The financial consequences alone of IVF can influence anxiety and become overwhelming. However, for many couples, the alternative is infertility, and the experience of infertility itself can also cause extreme stress and depression.
Complications
The major complication of IVF is the risk of
multiple births.
(External Link) This is directly related to the practice of transferring multiple embryos at embryo transfer. Multiple births are related to increased risk of pregnancy loss, obstetrical complications,
prematurity, and neonatal morbidity with the potential for long term damage. Strict limits on the number of embryos that may be transferred have been enacted in some countries (for example, England) to reduce the risk of high-order multiples (triplets or more), but are not universally followed or accepted. Spontaneous splitting of embryos in the womb after transfer can occur, but this is rare and would lead to identical twins. A double blind, randomised study followed IVF pregnancies that resulted in 73 infants (33 boys and 40 girls) and reported that 8.7% of singeton infants and 54.2% of twins had a birth weight of < 2500 g . However recent evidence suggest that singleton offspring after IVF is at higher risk for lower birth weight for unknown reasons.
Another risk of ovarian stimulation is the development of
ovarian hyperstimulation syndrome.
If the underlying infertility is related to abnormalities in spermatogenesis, it's plausible, but too early to examine that male offspring is at higher risk for sperm abnormalities.
Birth defects
The issue of
birth defects remains a controversial topic in IVF. A majority of studies don't show a significant increase after use of IVF. Some studies suggest higher rates for ICSI, while others don't support this finding. Hansen
et al. conducted a
systematic review of published studies (including ICSI) and found a 30-40% increase risk of birth defects associated with assisted reproductive technology when compared to children born after spontaneous conception. Possible explanations offered were the underlying cause of the infertility, factors associated with IVF/ICSI, culture conditions, and medications, however, the actual cause isn't known. Some believe that in vitro fertilization lacks the theory of "survival of the fittest" between contending sperm that occurs inside the uterus which may lead to the possibility of birth defects.
Cryopreservation
Embryo cryopreservation
If multiple embryos are generated, patients may choose to
freeze embryos that are not transferred. Those embryos are placed in
liquid nitrogen and can be preserved for a long time. There are currently 500,000 frozen embryos in the United States.
(External Link) The advantage is that patients who fail to conceive may become pregnant using such embryos without having to go through a full IVF cycle. Or, if pregnancy occurred, they could return later for another pregnancy. Spare embryos resulting from fertility treatments may be donated to another woman or couple, and embryos may be created, frozen and stored specifically for transfer and donation by using donor eggs and sperm.
Oocyte cryopreservation
Cryopreservation of unfertilised mature oocytes has been successfully accomplished, for example in women who are likely to lose their ovarian reserve due to undergoing
chemotherapy.
Ovarian tissue cryopreservation
Cryopreservation of ovarian tissue is of interest to women who want to preserve their reproductive function beyond the natural limit, or whose reproductive potential is threatened by cancer therapy. Research on this issue is promising.
Adjunctive interventions
There are several variations or improvements of IVF, such as ICSI, ZIFT, GIFT and PGD. An increasing number of fertility specialists and centers offer acupuncture as a part of their IVF protocol, or maintain a list of acupuncturists specialising in infertility.
ICSI
Intracytoplasmic sperm injection (ICSI) is a more recent development associated with IVF which allows the sperm to be directly injected in to the egg using
micromanipulation.
This is used where sperm have difficulty penetrating the egg and in these cases the partner's or a donor's sperm may be used. ICSI is also used when sperm numbers are very low. ICSI results in success rates equal to IVF fertilisation.
ZIFT
In Zygote intrafallopian transfer (ZIFT) eggs are removed from the woman, fertilised and then placed in the woman's fallopian tubes rather than the uterus.
GIFT
In gamete intrafallopian transfer (GIFT) eggs are removed from the woman, and placed in one of the fallopian tubes, along with the man's sperm. This allows fertilisation to take place inside the woman's body. Therefore, this variation is actually an
in vivo fertilisation, and not an
in vitro fertilisation.
PGD
PGD can be performed on embryos prior to the
embryo transfer. A similar, but more general test has been developed called
Preimplantation Genetic Haplotyping (PGH).
Acupuncture
An increasing number of fertility specialists and centers recognise the benefits of acupuncture and offer acupuncture as a part of their IVF protocol. Limited but supportive evidence from clinical trials and case series suggests that acupuncture may improve the success rate of IVF and the quality of life
A randomised, prospective study showed that acupuncture significantly (p<0.01) increased IVF implantation rates and pregnancy rates. Positive trends were also observed in miscarriage rates although the results were not statistically significant. The study has been criticised by one scientist for lacking traditional scientific practices when interpreting the data, and by another scientist that positive impact of acupuncture on IVF success rates isn't definitive. . However, assessments of nonpharmacological treatments must take into consideration additional methodological issues. This criticism is possibly arising from lack of understanding of methodological differences in clinical trials evaluating nonpharmacological and pharmacological treatments and in particular methodological issues in trials of acupuncture .
Electro-acupuncture in oocyte retrieval for IVF
Electro-acupuncture has a proven analgesic effect in oocyte retrieval for IVF.
Complementary medicines
Infertility patients commonly use complementary medicines. Health-care practitioners and fertility specialists need to be proactive in acquiring and documenting the use of these practices. There is a need to provide further information to patients on the use of CMs and therapies. Further research examining the reasons for use of CMs and therapies is needed.
(External Link)
Hypnosis
A study of
hypnotherapy suggests a higher success rate when integrated with treatment
(External Link). However, this study isn't without criticism. Experts say the study failed to take into account key differences between the groups compared in the study. These differences would have had a major influence on their chances of conceiving .
Ethics
Issues
The IVF process requires sperm, eggs and a uterus. To achieve a pregnancy any of these requirements can be provided by a third person:
third party reproduction. This has created additional ethical and legal concerns.
In a few cases laboratory mix-ups (misidentified gametes, transfer of wrong embryos) have occurred leading to legal action against the IVF provider and complex paternity suits. An example is the case of a woman in California who received the embryo of another couple and was notified of this mistake after the birth of her son.
Pregnancy past menopause
While menopause has set a natural barrier to further conception, IVF has allowed women to be pregnant in their fifties and sixties. Women whose uteruses have been appropriately prepared receive embryos that originated from an egg of an egg donor. Therefore, although these women don't have a genetic link with the child, they've an emotional link through pregnancy and childbirth. In many cases the genetic father of the child is the woman's partner. Even after menopause the uterus is fully capable to carry out its function.
Religious objections
The Roman Catholic Church is opposed to most kinds of in vitro fertilisation (although GIFT is accepted at certain conditions because fertilisation takes place inside the body and not inside a Petri dish (External Link)) and advocates that infertility is a call from God to adopt children. According to the Catholic Church, it "infringe[s] the child's right to be born of a father and mother known to him and bound to each other by marriage."
Also, embryos are sometimes discarded in the process, resulting in their demise. Catholics and many people of other faiths or none see embryos as human lives with the same rights as all others and, therefore, view the destruction of embryos as unacceptable.
Coping with IVF
Due to the emotional and financial aspects of infertility treatment, many feel isolated and sometimes become depressed. Online support forums and message boards have become a popular way for sufferers to exchange both information and support. Popular forums include Fertiliy Friends, IVFConnections, IVF.ca, Ivf-Infertility.com, INCIID, and IVF World.
Further Information
Get more info on 'In Vitro Fertilization'.
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