What is the reproductive technology of IVF like?

There are couples of childbearing age who want to have a child very much but have not been able to do so due to medical reasons. With the advancement of biological sciences and medical research, there is finally a remedy for such couples - they can pin their hopes on IVF technology to give birth to cute dolls!

In vitro fertilization (IVF): also known as in vitro fertilization (IVF), refers to the process of removing eggs and sperm separately, placing them in a test tube to fertilize them, and then transferring the embryonic precursor, the fertilized egg, back into the mother's uterus to develop into a fetus. IVF is a baby that is born when an egg and sperm are artificially fertilized and undergo early embryonic development outside the body, and then transferred back to the mother's uterus to develop.

In vitro fertilization (IVF) came about with the development of in vitro fertilization and was originally developed by British obstetrician Patrick Steptoe and physiologist Robert Steptoe. Steptoe, a British obstetrician, and Robert Edwards, a physiologist. The birth of "test tube baby" caused a sensation in the world scientific community, and was even called a major innovation in human reproductive technology, which also opened up a new way for the treatment of infertility. "In vitro fertilization (IVF) is a procedure in which a sperm and an egg are combined in a test tube to form a fertilized egg, which is then returned to the woman's uterus (embryo egg transfer) to mature in the uterine cavity and, like a woman who is normally impregnated, carry the pregnancy to full term and deliver the baby normally. For wives suffering from diseases such as blocked fallopian tubes, mature egg cells can be surgically removed from directly from the ovaries. The husband's sperm are then mixed in a test tube and allowed to combine in vitro to form a fertilized egg. In the case of a husband with few sperm or weak sperm motility, a robust sperm can be selected from his semen by means of an extremely fine pranic pipette and injected directly into the egg cell to form a fertilized egg.

After the fertilized egg forms an early embryo outside the body, it can move into the wife's uterus. If the wife's uterus is diseased, the early embryo can also be moved into the uterus of a woman who has volunteered to be a surrogate mother, thus giving birth to a little one with two mothers, one who gave him his genes, and one who gave him flesh and blood. The creation of this technique has been a boon to couples who can produce normal sperm and eggs but for some reason are unable to have children, and this technique is now being practiced in some parts of the country. the first attempts in this direction were made in 1944 by the Americans Locke and Menkin. The world's first test tube baby, Brown? Louise was born at 23:47 on July 25, 1978 at Oldham City Hospital in the U.K. Since then, the development of this research has been extremely rapid, and by 1981 it had expanded to more than 10 countries. The total number of IVF babies around the world is now in the thousands. Several medical schools in China have begun this research, and the first success was achieved at Beijing Medical College in 1985.

But which mother should a test-tube baby born to a surrogate mother live with? What if both mothers are inseparable from him? Such a dilemma would be difficult to solve by science and technology alone. You can also see from this that, while benefiting mankind, bioscience and technology will also bring some moral and ethical dilemmas to mankind, which should be a cause for concern.

Principle

"In vitro fertilization" is not a baby that actually grows up in a test tube. Instead, it involves removing a few eggs from the ovaries, letting them combine with the man's sperm in a laboratory to form an embryo, and then transferring the embryo to the uterus so that it can be implanted in the mother's uterus to carry a pregnancy. Normal fertilization requires that the sperm and egg meet in the fallopian tube, the two combine to form a fertilized egg, and then the fertilized egg returns to the uterine cavity to continue the pregnancy. In vitro fertilization (IVF) is simply a laboratory test tube that replaces the function of the fallopian tubes and is called "test tube baby". Although IVF was originally used to treat infertility caused by tubal obstruction, it has now been found to be helpful in cases of infertility due to endometriosis, sperm abnormality (abnormal count or morphology), and even unexplained infertility. Studies have shown a pregnancy rate of around 40% after one cycle of treatment, with a slightly lower birth rate.

Third-generation IVF

Advanced reproductive medicine research has pushed the self-control of human reproduction to new limits -- the first generation of IVF addressed infertility due to female factors; the second generation of IVF addressed infertility due to male factors; and the third generation of IVF has made breakthroughs. The breakthroughs made by the third generation of IVF are revolutionary, as it helps human beings to choose the healthiest offspring from the perspective of biological genetics, and provides future parents with genetic diseases with the opportunity to have healthy children.

Currently, China's third-generation IVF technology is fully mature, and the Center for Reproductive Medicine, headed by Prof. Guanglun Zhuang, is the only scientific research unit in China that carries out the clinical application of third-generation IVF.

The third generation of IVF technology can realize the principle of eugenics:

Because the Center for Reproductive Medicine will cultivate a number of embryos in test tubes for each couple who chooses the IVF technology to have a child, and before implanting the embryos into the mother's body, diagnose these embryos according to the principle of genetics (the method is called PGD for short), and from them, choose the one that is most compatible with the conditions of eugenics to be implanted into the mother's body. The method is referred to as PGD.

These eugenic embryos are selected in this way: some human genetic diseases, such as X-linked disorders, selectively develop in offspring of different sexes. In the case of a male hemophiliac, for example, his son will generally be normal; and his daughter will have a 50/50 chance of either being normal or carrying the hemophilia gene (hemophilia gene carriers generally do not develop the disease); in the case of a hemophiliac who is a woman, her son will develop the disease, and her daughter will have a 50/50 chance of either being normal or carrying the hemophilia gene. The eugenic principles of genetic diseases such as malnutrition and color blindness are the same as those of hemophilia. By understanding this genetic profile, it is possible to genetically test embryo cells grown in vitro and select embryos free of disease-causing genes for implantation in the uterus, thus avoiding the birth of a genetically diseased child.

Many hereditary diseases in humans can be prevented from being passed on to offspring using this PGD method, such as thalassemia and congenital stupidity.

Two couples weighed the pros and cons and made two different decisions: one agreed to use the third-generation PGD technique to choose to have a girl; and the other took a chance on a boy who, like his predecessor, would be a hemophiliac.

Similar to the latter situation Zhuang Guanglun encountered a lot, he said: "Although modern technology has been able to avoid some genetic diseases through genetic technology, but some people in the birth of a boy on the issue of traditional concepts are still y rooted."

The role of IVF - assisted reproductive technology

The blockage of the fallopian tubes due to various reasons prevents sperm and eggs from meeting, leading to infertility. The solution is to try to make the sperm and egg meet and fertilize outside the body, which is often referred to as IVF. This is often referred to as in vitro fertilization (IVF). The specific method is to use drugs to encourage both ovaries to grow more eggs, and then remove the eggs when they are mature and put them into a culture solution that simulates the environment of the human body, and then add treated semen to the solution, and then after a period of incubation, the sperm and eggs will fuse to form a fertilized egg and divide into 4-8 cells, and then pick out the 2-3 best-developed embryos and return them to the uterine cavity to continue to grow and develop. The medical term for IVF is in vitro fertilization-embryo transfer. This is the only option for couples who are infertile due to tubal failure, but of course, it can also be used to treat some other causes of infertility for which other methods of treatment have failed. IVF and embryo transfer developed on this basis can solve certain infertility problems of women, and at the same time provide an effective means of reproduction for carrying out genetic engineering of human beings, livestock and crops, and for preserving precious animals facing the crisis of extinction. In addition, in accordance with China's population policy of limiting the number of people and improving the quality of the population, scientific research in this area can open up a new way for the eugenic cause of the Chinese nation. IVF is a major achievement of modern science, which has ushered in a new era of embryo research and reproductive control.

Preparations needed for IVF

For IVF, you must have a marriage certificate, couple's ID card and birth certificate.

The man needs to have his semen tested and the woman needs to complete some basic tests, such as gynecological examination, diagnostic scraping, tubal permeability test, anti-sperm antibodies, liver function and Hepatitis B 2.5 pairs, routine blood analysis and coagulation time, and basal endocrine hormone measurements (on the 3rd day of menstruation), etc. If there is no abnormality, the doctor will provide you with an in vitro fertilization (IVF) certificate and a medical certificate. If there are no abnormalities, your doctor will create a medical history for you and tell you when to start IVF treatment.

General luteal phase, that is, the 21st day of menstruation, began to use drugs, so that the body of gonadotropins at a low level, the use of drugs about 8 days of menstruation, menstruation on the 3rd-7th day, began to intramuscular follicle stimulating drugs, 3 days after the b ultrasound to monitor follicle development, the adjustment of the dose of medication, the use of drugs to stimulate follicle development for 10 days, follicle development and maturity, which is guided by b ultrasound transvaginal fornix puncture can be taken out, and the eggs can be removed in the vaginal fornix. The eggs can be taken out by ultrasound-guided puncture through the vaginal vault and fertilized in vitro, and then put into the uterine cavity after 3 days of cultivation of the fertilized eggs to develop into embryos, and then put into the uterine cavity after transplantation and bed rest for 2-4 hours. The whole process is very painless and usually does not require hospitalization. One cycle of IVF costs 10,000-15,000 yuan (less than 10,000 yuan for domestic drugs).

Steps carried out in IVF

1, controlled ovulation

2, follicle monitoring

3, egg retrieval

4, sperm retrieval

5, in-vitro fertilization

6, in-vitro culture of the embryo

7, embryo transfer

8, progesterone supplementation after embryo transfer

9. Morning urine test on the 14th day after embryo transfer to determine pregnancy

10. 14 days after pregnancy, ultrasound to check the number of fetuses and the site of embryo implantation

Controlled ovulation:

Since the length of the natural menstrual cycle varies from person to person, and there are also differences in different cycles of the same patient, it is not easy to arrange for the timing of the retrieval of the eggs and there is only one dominant follicle developing in the natural cycle. follicle develops, only one embryo can be formed after fertilization, and the pregnancy rate of transferring one embryo is very low. Therefore, controlled superovulation is needed to enhance and improve ovarian function to achieve the goal of obtaining multiple healthy eggs without the limitation of natural cycles, providing multiple embryos for transfer, and synchronizing the development of the corpus luteum with the function of the endometrium as much as possible. Controlled super-ovulation generally involves the use of GnRHa to down-regulate FSH and LH in the body, and then administering HMG or FSH ovulation drugs to stimulate follicular growth in the ovaries, and adjusting the dosage of drugs according to the patient's responsiveness to the drugs, and the number of eggs obtained varies depending on the patient's age and the dosage of the drugs used.

Monitoring of follicles:

In order to evaluate the effect of ovarian stimulation and to determine the time of egg retrieval, the size of the follicles should be monitored by vaginal ultrasound, and blood tests for E2 (estrogen) should be performed to adjust the dosage of the medication. When two to three or more follicles are larger than 1.8 cm in diameter and the number of follicles over 1.4 cm is equal to the E2 value, human chorionic gonadotropin (hCG) can be injected to promote follicular maturation. Eggs are retrieved 34-36 hours after hCG injection.

Egg retrieval:

The most commonly used method of egg retrieval is to pass the needle through the vaginal fornix under local anesthesia, guided by vaginal ultrasound, and reach the ovary to absorb the egg, which is then immediately transferred under the microscope to a Petri dish containing embryo culture fluid and incubated at 37 °C. The eggs are then transferred to a culture dish containing embryo culture fluid, and then cultured in an incubator.

Sperm retrieval:

Sperm is retrieved on the same day as the egg retrieval. Hands were washed before sperm retrieval and semen was retained by masturbation method. The small cup given is sterile, do not touch the rim or the inside of the cup while retaining. The extracted semen was processed by upstream method or Percoll density gradient centrifugation.

In vitro fertilization:

The processed sperm and eggs are placed in the same petri dish 4 to 5 hours after egg retrieval and **** incubated together for 18 hours, then fertilization can be observed under a microscope. If the quality of the sperm is too poor for natural fertilization, fertilization must be forced by microinjection (refer to intracytoplasmic single sperm microfertilization).

Embryo transfer:

Fertilized eggs can be cultured in vitro for 48 to 72 hours to develop into 8-16 cell embryos. At this point, the number of embryos to be transferred is determined by the patient's age, previous pregnancies, and the quality of the embryos, and any excess embryos can be frozen for preservation. Embryo transfer is usually performed without anesthesia. Currently, most embryos are transferred 2 to 3 days after fertilization, but in our clinic, embryos are transferred 3 to 5 days after fertilization. Delaying embryo transfer is more demanding in terms of in vitro culture conditions, but delaying the transfer is more consistent with the physiology of pregnancy, and also eliminates poor-quality embryos through natural screening, which can increase the pregnancy rate and reduce the rate of multiple births.

Hormone supplementation after embryo transfer:

Currently, we mostly use injections to give progesterone to support the corpus luteum. If pregnancy is confirmed, then switch to hCG to continue supplementation until 10 weeks of pregnancy.

Fourteen days after embryo transfer, pregnancy can be determined by a urine test or blood draw.

Applicable people for IVF

1. Severe tubal disease, such as pelvic inflammatory disease leading to tubal blockage and fluid retention; or tubal tuberculosis with a normal endometrium; or tubal blockage after ectopic pregnancy

2. Endometriosis

3. Immune infertility, with the presence of anti-sperm antibodies in the man's semen or in the woman's cervical mucus

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4. Male factor, i.e., oligospermia, weak spermatozoa, abnormal spermatozoa

5. Unexplained infertility

6. Failure of treatment for other causes of infertility

7. Genetic diseases that require pre-transplantation diagnosis

8. Others: e.g., follicular dysfunctionality syndrome, etc.

Patient Preparation before Visit

Patient Preparation

First, it is necessary to define the cause of infertility, which includes the presence of anti-sperm antibodies in the male semen or female cervical mucus. p>First of all, it is necessary to clarify the cause of infertility and find out whether it is suitable for IVF. It is best to bring along information and certificates of past examinations and treatments to avoid wasting time on repeated examinations. The information includes:

1. The report of tubal patency test: X-ray film of uterine tubal iodine oil imaging, report of ultrasound fluid passage, or hospital certificate of laparoscopy or laparoscopic surgery are all acceptable.

2. Examination for ovulation: pathologic report of the endometrium within one year and basal body temperature slips of the last three months.

3. The report of routine laboratory examination of semen of DD in the last six months.

4. Hepatitis B surface antigen antibody, e antigen antibody and core antibody of both husband and wife, Hepatitis C antibody, liver function, blood type laboratory report, blood sedimentation, tuberculin test of the woman; serum HIV antibody.

When all the above information is complete, you can visit the Fertility Treatment Center, and before officially entering the cycle, you can visit the clinic ten days prior to the expected menstrual period for another gynecological examination and a test transfer to detect the depth of the uterine cavity and the direction of the catheter during the transfer of the embryo.

The success rate of IVF

The success rate of IVF is a question that should be of concern to those who are preparing to undergo IVF treatment. The success rate of IVF is a matter of concern for those who are preparing to undergo the IVF technique. Since the birth of IVF more than 20 years ago, assisted human reproduction technology has evolved considerably. Especially in the last few years, because of the maturity of various technologies, including the improvement of cell culture fluid and the rich experience of medical personnel, the success rate of "in vitro" babies has been gradually increased worldwide, from the original 20-25% to 60% or even higher.

The success rate of IVF depends on a number of factors, including endocrine and laboratory conditions, the skill level of the technician, and of course, the age of the patient, the condition of her uterus and ovaries, and the presence of other diseases, all of which affect the success rate. For example, it is affected by the age of the woman, which is one of the biggest influencing factors. The success rate of IVF for women between the ages of 25 and 35 is higher than the average of 30%-40%, and some can reach 50% or higher, but the success rate gradually decreases after the age of 35, and only reaches about 20% at the age of 40, because the quality and quantity of the eggs decline with age. The reason for this is that the quality and quantity of eggs decline with age.

How long does IVF "live" in the test tube

After the eggs are removed, they are incubated with sperm in the test tube***, with about 100,000 sperm needed for each egg. After fertilization, the fertilized egg splits to form an early embryo, i.e., two to eight split balls can be embryo transfer (ET), at this time about 48 hours after the egg collection, this time can also be changed according to the specific circumstances, such as pushing back a day, this time may also be more conducive to the preferential selection of embryos. If it is too early, the intrauterine environment may not be favorable for receiving embryos. A test transfer is usually performed in an outpatient clinic during the cycle before the stimulation cycle to understand the orientation of the uterus, the angle between the cervix and the body of the uterus and the length of the uterine cavity, and to dilate the cervix slightly. After sterilizing the vulva during transplantation, the cervix is exposed with a speculum, wiped clean, and the cervix and fornix and cervical canal are again wiped with culture fluid to remove as much mucus as possible from the cervical canal. The movements should be as gentle as possible to minimize irritation of the uterine muscles. The embryo is injected using a special transfer tube. Entering the uterine cavity, the embryo is injected 0.5 cm from the uterine fundus. After waiting for 1 minute, the head is turned 90° to shake off any drop of fluid that fails to drop, and then the catheter is slowly withdrawn. After the catheter is withdrawn the embryo is also checked under the microscope for failure to bring out the embryo. After the transfer the patient may lie on the back with the buttocks elevated, or in a prone position if the uterus is very forward-flexed, with the aim of keeping the injected embryo above the uterine cavity. Lying still for about 3 to 6 hours allows for urination to avoid urine retention. HCG 5000 international units and progesterone 30mg injected on the day of transplantation, and then routinely injected daily progesterone, such as 14 days after the urine HCG negative that is to stop the injection, pregnant people continue until the ultrasound can be seen after the fetal heart and then gradually reduce the amount.

The development of IVF technology in China

The study of IVF has a long history, as early as the 1940s, scientists began to experiment on animals, and in 1947, the British journal Nature reported that the eggs of rabbits were recovered and used in a test tube. In 1947, the British journal Nature reported the experiment of transferring the eggs of rabbits to other rabbits and giving birth to young rabbits on borrowed bellies. 1959 Chinese-American biologist Zhang Minjue combined the sperm and eggs recovered from rabbits after mating with in-vitro fertilization, and he also transplanted the fertilized eggs into the oviducts of other rabbits, giving birth to normal young rabbits on borrowed bellies. The successful completion of in vitro fertilization experiments on rabbits made Zhang Minjue a pioneer in in vitro fertilization research. The results of his animal experiments laid a good foundation for later research on in vitro fertilization and in vitro fertilization.

The world's first IVF baby, Louis Brown, was born on July 25, 1978, in the U.K. The success rate of the earliest stage of IVF was only 2.94%, and in June 1980, the first IVF baby was born in Australia, and 15 cases were born in the U.K. and Australia before November 1981, and the first case was born in the U.S. in December 1981, and now 10,000 babies have been born around the world. Now more than 10,000 cases have been born worldwide, and the pregnancy success rate has improved rapidly, with the pregnancy rate increasing to 20-30%. The hope for the treatment of tubal factor infertility has shifted from tubal microplasty in the 60's and 70's to IVF-ET technology. Of course, the choice of these two treatments depends on the patient's specific situation. China's work in this area started relatively late, the first case of IVF was born in Taiwan Province of China in 1985, and one case was also born in Hong Kong in 1986. The first IVF baby in mainland China was born on March 10, 1988, and is now in her late teens, smart and healthy. Her mother was a 38-year-old patient with 20 years of primary infertility and bilateral tubal failure. Hunan Medical University and the Reproductive Medicine Research Center of the First Affiliated Hospital of Sun Yat-sen Medical University have successively researched on it. So far hundreds of medical institutions in China have carried out IVF-ET, but the number of cases done is not yet large, and their clinical pregnancy success rates are all up to 20% or less. In terms of new technology, Shandong Provincial Hospital reported the first successful gamete intrauterine transfer pregnancy in China, which was delivered in May 1992. Zhongshan Medical University conducted microscopic operation intracytoplasmic single sperm injection (ICSI) IVF baby was born in April 1996, these successes are a sign of the mainland China's in vitro fertilization, embryo transfer is moving forward.

World record of IVF births

1978.7.25 UK Female The world's first IVF baby

1978.10.3 India Female India's first

1979.1.14 UK Male The first male baby

1979.6.23 Australia Female Australia's first

1980.6.6 Australia A male and a female First IVF twins

1981.10.19 UK Female First mulatto IVF baby

1981.12.28 USA Female First in USA

1982.1.20 Greece Female First in Greece

1982.2.24 France Female First in France

1982.2.25 France Female First in France

1982.2.25 France Female First in France

1982.6.25 UK Female The mother of the nation's first IVF baby born again

1982.9.22 Israel Female Israel's first

1982.9.27 Sweden Female Sweden's first

1983.5.20 Singapore Male Southeast Asia's first IVF baby

1983.6.8 Australia Two females and a male first IVF baby

1983.6.9 Female Southeast Asia's first IVF baby

Australia Female .8 Australia Two females and one male First triplets

1984.1.16 Australia Four males First quadruplets

1985.4.16 Taiwan, China Male Taiwan's first IVF babies

1988.3.10 China Female Mainland China's first IVF babies

Flaws

Today, scientists can't accurately explain why IVF babies are born with greater health risks. Some assisted reproduction (IVF) experts point out that the high incidence of disease problems linked to IVF can be traced to defects in the eggs used to create the child's embryo.

Three new studies have shown that an average of 42 percent of eggs prepared for IVF carry genetic variants that can make it difficult to deliver the created fetus. Some experts imply that this is down to the drugs used to stimulate ovulation. To make it easier to obtain eggs, doctors are required to give women undergoing in vitro fertilization procedures ovulation drugs beforehand.

Eggs used to create embryos in laboratories often carry genetic defects, so more IVF experts are calling for all eggs used to be screened, the BBC reported. Policies regulating IVF in Britain now require that the eggs of women over the age of 35 be scanned for abnormal chromosome numbers.

This discovery has prophetically fueled an increased demand for the use of pre-implantation genetic diagnosis (PGD), a procedure that checks for abnormal genes in a single cell of an early embryo. The procedure can sometimes cause the death of an embryo outright, but more importantly, as a "search-and-destroy" method, it effectively reduces the number of children deemed genetically unfit.

The first IVF babies are now adults. The birth of their next generation has compounded the health problems caused by IVF.

Consequences of misuse

Since the world's first test-tube baby was born in 1978, more than 3 million babies have been born through in vitro fertilization around the world***, the International Commission on the Oversight of Assisted Reproductive Technology said in a report released on June 21, 2006***. The Commission's expert, Jacques Mouzon, said that about three million babies are born each year worldwide through IVF. Mouzon said about 1 million IVF procedures are performed worldwide each year and about 200,000 babies are born annually.

While IVF has spawned an industry with annual revenues of more than $100 million after more than two decades of rapid growth, it has been increasingly criticized for safety concerns that have recently come to the fore.

In fact, the use of in vitro fertilization technology already posed many problems before it was discovered that IVF babies could be born with additional health risks. Many women believed that with IVF they could postpone having children indefinitely and pay when they were ready. But most don't realize that the average pregnancy rate for IVF is only 25.1 percent and the fertility rate 18.5 percent; nor do they know that the procedures are painful and often dangerous.

Professor He Fangfang of the Center for Assisted Reproduction and Prenatal Diagnosis in the Department of Obstetrics and Gynecology at the Peking Union Medical College Hospital said the number of infertile people in China is now rising year by year, and that "in addition to congenital disorders, many people are holding themselves back." Many women feel they can put off having children because of the pressure of their work, making them infertile when they could be fertile, and in vitro fertilization technology is only used by 1 to 2 percent of infertile women.

In China, one in 10 couples of childbearing age is infertile. The huge market demand has led many medical institutions to carry out in vitro fertilization techniques. Geneticist Lu Guang believes the misuse of this technique, if unchecked, will affect China's demographic security. She said, "This is much more serious than the consequences of grain extinction caused by farmers buying fake seeds. Once the application and management of IVF are out of control, problems such as defective children, imbalance in the male-to-female ratio and inbred marriages will emerge one after another and seriously affect China's demographic security."

In vitro fertilization technique explained

Unmatured egg culture (IVM): common IVF technique has helped many patients realize their dream of having children, but there are still some patients, such as those with polycystic ovary syndrome and ovarian hyperstimulation syndrome, who clinically need to use immature egg culture technique. This technique is characterized by removing the eggs from the body at a very young stage and culturing them into mature eggs under specific conditions outside the body, thus avoiding the problem of difficult maturation of eggs in the body in patients with polycystic ovary syndrome and the problem of difficult medication to promote ovulation in patients with ovarian hyperstimulation syndrome.

The success rate of IVM is lower than that of first- and second-generation IVF, ranging between 15 and 30 percent, and only a few fertility centers in China have the technology.

Natural Cycle IVF: Natural Cycle IVF is a new treatment that people have started to pay attention to in the last 2 or 2 years. The rationale is that some patients have good ovarian reserve and can take immature egg culture technology to cultivate their own reserve follicles into mature follicles, and then undergo IVF. This eliminates the need for ovulation stimulation drugs, avoids repeated stimulation of the ovaries by drugs, reduces ovarian hyperstimulation, and also reduces the cost of treatment, as the cost of drugs accounts for 50% of the cost of conventional IVF treatment. Conventional IVF, if it fails, usually requires resting the ovaries for 2-3 months before proceeding to the next cycle. However, with natural cycles, since there is no medication to stimulate the ovaries, after a failure you can move on to the next cycle immediately in the following month. This time continuity also makes it easier for working women and older women to shorten their treatment cycles.

Natural cycles have not been widely adopted and there is a lack of definitive literature on their success rates, but it is generally accepted that the success rate of natural cycles is lower than that of ovulation induction cycles, with excellent centers achieving more than 30%.

Egg freezing: Egg freezing is a technique that involves freezing and storing eggs in liquid nitrogen and then thawing the eggs when they are needed. This technique is suitable for patients with premature ovarian failure and loss of ovarian function, as well as some professional women who wish to delay childbearing. Patients with premature ovarian failure or loss of ovarian function, whose hopes come mainly from eggs donated by other patients, can have their eggs frozen by egg freezing and then retrieved for use when needed. In addition, some professional women wish to delay childbearing, but are concerned about the decline in egg quality as they age, so they can take egg freezing technology to freeze and store their eggs when they are young and then use them when they are older.

The difficulty with this technique is that because of the large amount of fluid in the follicles, ice crystals tend to form during the freezing process and damage the tissue structure of the follicles, resulting in a low success rate.

Frozen embryos: IVF technology can go beyond the limits of human ovulation, creating multiple eggs and forming multiple embryos in one menstrual cycle through medicated ovulation. But multiple embryo transfer not only does not improve the success rate, but also increases the occurrence of multiple births, increasing the risk of maternal and infant mortality and complications. Therefore, countries around the world generally have corresponding regulations to limit the number of embryos implanted, and due to technological advances, an international trend toward single embryo transfer has begun to develop. In China, the maximum number of embryos to be transferred is currently set at 3. For patients with more than 3 embryos, the extra good quality embryos can be frozen in liquid nitrogen and if the transferred embryos are unsuccessful, the frozen embryos can be transferred in the next treatment cycle. The success rate of frozen embryos is typically 10 percent lower than the success rate of fresh cycles of IVF.

The world's first frozen embryo IVF was performed at Monash IVF in Australia, and almost all centers in the country have now mastered the frozen embryo technique.

What are the complications of IVF

Ovarian hyperstimulation: about 1 week after egg retrieval, a small number of patients have the following symptoms: abdominal distension, ascites (or even hydrothorax), enlarged ovaries, gastrointestinal discomfort, and oliguria, etc., which will last more than two months once pregnancy is achieved, and will gradually be eliminated. This phenomenon is most common in polycystic ovaries. This phenomenon is often seen in patients with polycystic ovaries and some people who are sensitive to drugs, such people have dozens of follicles developing at the same time.

Multiple pregnancies: In order to improve pregnancy success rates, doctors usually transfer more than one pregnancy, which poses a risk of multiple pregnancies. The patient may wish to have more than one baby, but multiple pregnancies increase many risks: such as hypertensive syndrome of pregnancy, miscarriage, stillbirth, preterm labor, and low-birth-weight babies. Additionally, multiple births can be financially, physically, and emotionally taxing for the parents, and these problems can cancel out the joy of parenthood. The goal of treating infertility is to obtain a child, and the first step in avoiding multiple births for the health of the mother and child is to reduce the number of embryos transferred, usually to no more than three. If multiple births occur embryos can be reduced to 1-2 embryos by reduction techniques.