In Vitro Fertilization 1
Running head: IN VITRO FERTILIZATION
In Vitro Fertilization
Jenna Felesena
BIO 3400
Professor Chen
Aurora University
December 10, 2007
In Vitro Fertilization
Many couples have a hard time conceiving a child naturally. There are many techniques that can be applied in order to conceive, but the most controversial one to date has been in vitro fertilization or IVF. For those who were unable to reproduce, adoption had been the main choice, until 1981. At that time, the United States medical program began to offer another method, in vitro fertilization (Kimball, 2007). This particular method has helped infertile women, or women that are unable to become pregnant, to have children. In vitro fertilization has offered new hope for those people who are unable to have their own biological child.
In order to understand how in vitro fertilization works, it is important to understand sexual reproduction, because it an important aspect in the continuation of the human species. This is done by the conjoining of two gametes, the sperm and the egg. Each zygote, or the product of the conjoined sperm and egg, requires both nourishment and motility in order to come together. The sperm provides the motility via a tail, and the eggs have food. A human male contains the sex organs needed to create and distribute sperm to a female.
Spermatogenesis, or the creation of sperm, takes place in the human male’s testes. First, a primary spermatocyte undergoes its first meiotic division to create secondary spermatocytes. After a second meiotic division takes place, spermatids are created. These spermatids then develop into sperm, which contain a head, a midpiece and a tail. A haploid set of chromosomes are stored in the head, a single centriole and mitochondria are stored in the midpiece, and the tail is used primarily for movement (Kimball, 2007). Once the sperm is created, it must be distributed to a female’s sex organ in order for fertilization to be complete.
Kimball (2007) states that, “the responsibility of the female mammal for successful reproduction is considerably greater than that of the male” (para. 7). The female body is designed to provide a habitat for another growing human being. For this to occur, the female must be able to create an egg, to receive sperm from a male, be able to fertilize and embed a growing fetus in the uterus, and provide food and nutrients to the growing embryo (Kimball, 2007).
Just as the male produces sperm via spermatogenesis, the female produces eggs via oogenesis. First, a diploid stem cell, or oogonium, goes through mitosis and creates a primary oocyte. After first meiotic divion occurs, a secondary oocyte and a polar body are formed. Finally, the egg is created after the secondary oocyte goes through second meiotic division. As previously mentioned, in order for fertilization to take place, a sperm and an egg must unite to form a zygote. When this takes place, second meiotic division is complete. Without fertilization, meiosis II would stop during metaphase. (Kimball, 2007)
After seeing how fertilization takes place, one can better understand how in vitro fertilization works. IVF is described as fertilization that takes place outside of a woman’s body. In fact the phrase “in vitro” refers to a culture container, because, in most cases, fertilization takes place in a laboratory dish. A woman still has to be able to produce eggs in order for IVF to take place. During a woman’s ovulation cycle, eggs are produced. In IVF, hormones are given to a woman so she will produce numerous eggs. Once the eggs are produced, they are surgically removed directly after ovulation has occurred by using “ultrasound imaging to guide a hollow needle through the pelvic cavity” (American Pregnancy Association, 2007, para. 3). Multiple eggs are collected to ensure that fertilization will take place. Getting sperm from a male is completed by ejaculation, but the sperm must be motile and functioning. Once the sperm and egg have been extracted, they are mixed together in a culture container and left for several days (usually 3-6 days). The fertilized eggs are then placed back inside the mother’s uterus where they will hopefully implant and begin a healthy pregnancy (American Pregnancy Association, 2007).
It is important to understand that there are some medical risks and concerns that are incorporated in IVF. One concern many couples have when considering IVF is the fertilization success rates. In an article by Banerjee (2007), the fact that success rates tend to out way the risks was addressed. Because treatments, expenses, and risks vary from one person to the next, and there truly is no guarantee IVF will work, the pressure to address high success rates burdens many different clinics (para. 8). According to the American Pregnancy Association (2007) the birth rate is best for women under the age of 35. The exact percent per age group is as follows: “approximately 30 to 35% for women under age 35,” “25% for women ages 35 to 37,” “15 to 20% for women ages 38 to 40,” and “6 to 10% for women ages over 40” (para. 13). Another concern of IVF is multiple births. Because numerous eggs are retrieved to ensure fertilization, the risk of most, if not all, of these eggs fertilizing and implanting in the uterus are greatly increased. Some people are then faced with the decision of fetal reduction, or the removal of one of more extra fertilized embryos. This is particularly difficult for a family, because it is almost like killing an unborn child.
One risk women take when enduring IVF treatment is “Ovarian Hyper stimulation Syndrome,” which means that the ovaries have been stimulated too much. This occurs due to the ovarian stimulation process and can cause a great deal of pain. Some side effects of this syndrome are “nausea, vomiting, lack of appetite, or a feeling of being bloated” (American Pregnancy Association, 2007, para. 17). The medical risks and concerns of IVF are very serious and need to be taken into consideration, but so does the community’s reaction to this advancement in scientific technology. Because these children are born outside of the womb, in a test tube, opponents of in vitro fertilization claim it is going against nature and disreputable. Another reason IVF has been seen as controversial is because when scientists take unfertilized eggs from women, the stimulation used to attain their egg had serious side effects.
In vitro fertilization has found a place in this country’s medical community, but how they decide it should be used will affect its future. IVF has not been around for very long, but has shown great progress. It is an amazing advancement in the world of science and technology. It allows numerous infertile couples to become pregnant and have biological children. There are numerous in vitro fertilization clinics throughout the United States which offer this service. Although IVF has helped many people, there are still those that oppose the idea. Not only does the idea of a test tube baby appear immoral to some citizens, but it also has created controversy in the medical society. This is primarily due to the effects IVF has on women undergoing the procedure. Women that endure IVF treatments are at risk of multiple births, embryo reduction, or “Ovarian Hyper stimulation Syndrome.” Just like any other debate, IVF contains a number of pros and cons. As long as the advancements in scientific technology are used responsibly and not taken advantage of, then the ability of infertile people to reproduce out-weight the cost and potential side affects. In vitro fertilization offers new hope for those people who are unable to have their own biological child.
References
American Pregnancy Association (2007) In vitro fertilization: IFV. Infertility. Retrieved December 4, 2007 from http://www.americanpregnancy.org/infertility/ivf.html
Banerjee, A. K. (2007) An insight into the ethical issues related to in vitro fertilization. Internet Journal of Health, vol. 6 Issue 2, p. 11. Retrieved December 4, 2007 from Academic Search Premier.
http://web.ebscohost.com.library.aurora.edu/ehost/detail?vid=11&hid=109&sid=3591e4f7-57bf-473b-8fa0-d852bef71e6e%40sessionmgr102
Kimball, J. W. (June 23, 2007) Sexual reproduction in humans. Kimball’s Biology Pages. Retrieved November 12, 2007 from
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Sexual_Reproduction.html
References
American Pregnancy Association (2007) In vitro fertilization: IFV. Infertility. Retrieved December 4, 2007 from http://www.americanpregnancy.org/infertility/ivf.html
In Vitro Fertilization is commonly referred to as IVF. IVF is the process of fertilization by manually combining an egg and sperm in a laboratory dish. When the IVF procedure is successful, the process is combined with a procedure known as embryo transfer, which is used to physically place the embryo in the uterus.
What is involved with in vitro fertilization?
There are basically five steps in the IVF and embryo transfer process which include the following:
- Monitor and stimulate the development of healthy egg(s) in the ovaries.
- Collect the eggs.
- Secure the sperm.
- Combine the eggs and sperm together in the laboratory and provide the appropriate environment for fertilization and early embryo growth.
- Transfer embryos into the uterus.
Step 1: Fertility medications are prescribed to control the timing of the egg ripening and to increase the chance of collecting multiple eggs during one of the woman's cycles. This is often referred to as ovulation induction. Multiple eggs are desired because some eggs will not develop or fertilize after retrieval. Egg development is monitored using ultrasound to examine the ovaries and urine or blood test samples to check hormone levels.
Step 2: Your eggs are retrieved through a minor surgical procedure which uses ultrasound imaging to guide a hollow needle through the pelvic cavity. Sedation and local anesthesia are provided to remove any discomfort that you might experience. The eggs are removed from the ovaries using the hollow needle, which is called follicular aspiration. Some women may experience cramping on the day of retrieval, which usually subsides the following day; however, a feeling of fullness or pressure may last for several weeks following the procedure.
Step 3: Sperm, usually obtained by ejaculation is prepared for combining with the eggs.
Step 4: In a process called insemination, the sperm and eggs are placed in incubators located in the laboratory which enables fertilization to occur. In some cases where fertilization is suspected to be low, intracytoplasmic sperm injection (ICSI) may be used. Through this procedure, a single sperm is injected directly into the egg in an attempt to achieve fertilization. The eggs are monitored to confirm that fertilization and cell division are taking place. Once this occurs, the fertilized eggs are considered embryos.
Step 5: The embryos are usually transferred into the woman's uterus anywhere from one to six days later, but most commonly it occurs between two to three days following egg retrieval. At this point, the fertilized egg has divided to become a two-to-four cell embryo. The transfer process involves a speculum which is inserted into the vagina to expose the cervix. A predetermined number of embryos are suspended in fluid and gently placed through a catheter into the womb. This process is often guided by ultrasound. The procedure is usually painless, but some women experience mild cramping.
These steps are followed by rest and watching for early pregnancy symptoms. A blood test and potentially an ultrasound will be used to determine if implantation and pregnancy has occurred.
Are there variations of in vitro fertilization?
Gamete intrafallopian transfer (GIFT) and zygote intrafallopian transfer (ZIFT) are two procedures related to IVF.
GIFT is similar to IVF, but the gametes (egg and sperm) are transferred to the fallopian tubes rather than the uterus, and fertilization takes place in the tubes rather than in the laboratory. GIFT also involves a laparoscopic surgical procedure to transfer the sperm and egg into the tubes. GIFT accounts for approximately 2% of assisted reproductive technology (ART) procedures in the United States.
ZIFT differs from GIFT in that the fertilization process still takes place in the laboratory versus the fallopian tubes. It is similar to GIFT in that the fertilized egg is transferred into fallopian tubes, and it involves a laparoscopic surgical procedure. ZIFT accounts for less than 1.5% of assisted reproductive technology (ART) procedures in the United States.
How successful is in vitro fertilization?
The success rate of IVF clinics depends on a number of factors including patient characteristics and treatment approaches. It is also important to realize that pregnancy rates do not equate to live birth rates. In the United States, the live birth rate for each IVF cycle started is approximately:
· 30 to 35% for women under age 35
· 25% for women ages 35 to 37
· 15 to 20% for women ages 38 to 40
· 6 to 10% for women ages over 40
The success rates of individual clinics are published on the web site of the Centers for Disease Control and Prevention.
When comparing success rates of different clinics, it is important to know what type of pregnancies are being compared. A chemical pregnancy is one confirmed by blood or urine tests, but a miscarriage may occur before confirmation through an ultrasound. A clinical pregnancy is one verified by ultrasound. After a clinical pregnancy has been verified, a miscarriage may still occur, but it is less likely.
What if I don’t produce healthy eggs or my husband is sterile?
IVF may be done with a couple’s own eggs and sperm or with donor eggs, sperm, or embryos. Some couples choose to use donor eggs, sperm, or embryos because of genetic concerns. Donor eggs are used in approximately 10% of all assisted reproductive technology (ART) cycles.