Example Of Normal Process Of Fertilization Essay

Background

History of IVF
In vitro fertilization in humans: procedure
Step i: Superovulation
Step ii: Egg retrieval
Step iii: Insemination and fertilization
Step iv: Embryo culturing
Step v: Embryo transfer
Prevalence
Infertility rates in USA
IVF US statistics
IVF international statistics
Risks of in vitro fertilization
In vitro fertilization and cancer
In vitro fertilization and birth defects
In vitro fertilization and chromosomal aberrations
In vitro fertilization and multiple births
In vitro fertilization, low birth weights, and increased prematurity
In vitro fertilization and back pain
Ethical dilemma in in vitro fertilization
Religion
Extra embryos
Multiple births
Conclusion
Importance of IVF
Reducing risks
In Vitro Fertilization
BACKGROUND
In normal human sexual reproduction, fertilization takes place in the fallopian tubes of the female. This is a process in which a sperm from the male fuses with the egg the female to form a zygote. The zygote then divides by the process of mitosis ending up in a structure called blastocyst which becomes attached to the uterine wall; a process called implantation. However, in instances where a male or a female is infertile an artificial technique is used to make fertilization a success.
The artificial technology used to aid the process of fertilization in infertile individuals is known as assisted reproductive technology (ART); one of them being in vitro fertilization (IVF). IVF is a procedure by which an ovum is fertilized by spermatozoa outside the body. Its history in animals dates back to 1930’s with the first IVF procedure carried out in rabbit oocytes. However, this fertilization was not successful. Thereafter, extensive research and dedication led to the first successful in vitro fertilization in rabbits in the late 1950’s. In 1978, a breakthrough in human in vitro fertilization led to the birth of Louise Brown (Squires and Kaplan 2).

IN VITRO FERTILIZATION IN HUMANS: PROCEDURE

In humans, the process of in vitro fertilization is carried out in the laboratory by combining the female’s ovum with the male’s spermatozoa in a laboratory dish. Below are the five steps of this type of in vitro fertilization.
Step i: Superovulation
This involves giving a woman fertility drugs which are meant to increase egg production. Unlike the normal one egg production per month, these drugs make the ovaries to produce numerous eggs. As this happen, the woman is given regular transvaginal ultrasounds meant to examine her reproductive system and especially check on the ovaries and hormonal levels.
Step ii: Egg retrieval
Follicular aspiration, a type of minor surgery, is carried out so as to remove the eggs from the woman’s reproductive system. During this time, the woman is put under medication so as to reduce pain. The procedure involves insertion of a needle into the vagina, then into the ovary, and finally the follicles where the eggs are found. The needle is attached to a suction device which sucks out the ova and fluid out of the follicles.
Step iii: Insemination and fertilization
Insemination is the process of mixing of the ova and spermatozoa. After insemination, the mixture is placed in a controlled chamber where sperm fertilizes the eggs forming a zygote. If there are doubts about the chances of fertilization, the sperms can be injected directly into the ovum.
Step iv: Embryo culturing
The fertilized egg (zygote) undergoes cell division, mitosis, forming an embryo. The embryo is then allowed to grow in an artificial medium before being transferred to the uterus. This process is known as embryo culture. In the medium, embryo divides mitotically forming a mass of cells called cleavages. Cleavages further divide forming a hollow structure called blastocyst. Embryo transfer takes place either at cleavage or blastocyst stage.
Step v: Embryo transfer
This is usually done three to five days after fertilization. A catheter containing the embryo at cleavage or blastocyst stage is inserted in the vagina, via cervix, and finally into the womb. The embryo gets attached to the wall of the uterus resulting in pregnancy. In case twins are needed, two embryos can be placed in the womb.

PREVALENCE

With infertility rates of women at 6.7 million in the USA, there has seen an upsurge in demand for this technique for treatment of infertility. Statistics show that more than 176,247 babies have been born using this approach in the US in 2012. Worldwide, a total of two million children have been born out of IVF (Squires & Kaplan 2).

RISKS OF IN VITRO FERTILIZATION

Several studies have been carried out to assess the risks of in vitro fertilization. The risks range from those that occur during the removal of egg from the ovaries, fertilization of the eggs, and transfer of the embryo to the woman’s womb. These risks include chromosomal aberrations, genetic mutations, cancer, high death rates of the fetus, birth defects in children, and women’s health risks. Some of the health risks are discussed below.
In vitro fertilization and cancer
A correlation between in vitro fertilization and different types of cancers both in children and women have been found in various studies. For instance, children born through in vitro fertilization have been found to have higher risks of developing leukemia as compared to those born the natural way (Petridou et al. 934). On the contrary, in a study to determine the relationship between in vitro fertilization and breast cancer no general rise in the rate of breast cancer in women who underwent IVF was reported. However, an increase in breast cancer rates was found in women who had undergone IVF at a young age (Stewart et al. 337). Similarly, Brinton et al. (1192) established that women who had received four cycles of IVF had a higher risk of developing breast, endometrial, and ovarian cancers as compared to those with less. However, there was no significant difference between women with less than four cycles and those with no fertility treatment.
In vitro fertilization and birth defects
Several birth defects have been found in children born via IVF. For instance, in vitro fertilization has been correlated with a high risk of polydactyly and particularly polydactyly of the hands (Healthy Quality Ontario 20). In different study to compare congenital abnormalities of infants born through assisted reproductive techniques such as IVF with those born naturally in Tehran, Farhangniya et al. (220) noted that a difference in risk between the two groups. Those born via IVF had a higher risk for the defect. Furthermore, the study reported that IVF infants had musculoskeletal and urogenital malformations as the most prevalent of major congenital malformations.
In vitro fertilization and chromosomal aberrations
This refers to changes in chromosomal structure as a result of deletion, addition, substitution, or duplication. The most common type of aberrations in IVF includes monosomies and trisomies which occur as a result of failure of chromosomes to separate in reduction division of meiosis. A study by Simon et al (90) revealed that aneuploidy were higher than normal in embryos obtained after IVF from frequent abortion women as compared to those with less frequent abortions who had undergone IVF. Moreover, the incidences of monosomies were found to be six times more common than trisomies in recurrent abortion women than in non-abortion ones with IVF.
In vitro fertilization and multiple births
In the past forty years there has been a substantial rise in the use of fertility treatments in the US. Consequently, there has been an increase in the number of multiple births (Kulkarni et al.). This is further supported by Kallen et al. (382) in a study of trends of multiple births in Australia from 1982-2001. The study found out that the increased rates of multiple births were attributed to IVF. These multiple births in turn increase the risks of miscarriage, gestational diabetes, pre-eclampsia, and need for forceps delivery which can pose a complication to the mother as well as the baby. Similarly, Wright et al. (2) asserted that multiple births from IVF are associated with complications in pregnancy, premature birth, lower birth weights, and long-term disability in children.
In vitro fertilization, low birth weights, and increased prematurity
IVF is also one of the contributing factors to low birth weight and prematurity. A study seeking to establish birth characteristics in a sample of women with infertility treatments in Sweden established that female having infertility problems due to female causes had approximately 2.4 times higher chances of giving birth to a low birth weight baby as compared to those of male and unexplained reasons (Vikstrom et al.). This is further corroborated by Kermani et al. (451) who found out that the number of low birth weight infants from in vitro fertilized women outnumbered those from normal women by six times.
In vitro fertilization and back pain
The prevalence of back pain during pregnancy is reportedly higher in in vitro fertilized women than in spontaneously fertilized ones. In a study to determine the difference in back pain frequencies between in-vitro fertilized and spontaneous pregnancies women, 31 pregnant women from in vitro fertilization treatment were compared with 200 from spontaneous pregnancies. It was found out that back pain prevalence rates were two times higher in IVF than spontaneous pregnancies (Kristiansson et al. 3234).

ETHICAL DILEMMA IN IN VITRO FERTILIZATION

The process of IVF has attracted so much debate especially from religious groups such as Christians and Muslims. Their arguments are based on religious teachings which advocates for the natural way of giving procreation. Another ethical dilemma is low utilization of extra embryos in donor oocyte. Given that IVF involves removal of large number of eggs from the woman’s ovary, some of them will end up being unused. Thirdly, the need to avoid multiple births raises ethical dilemma among physicians. In most countries, for example Belgium and Sweden, the recommended number of embryo transferred after IVF is one so as to avoid complications resulting from multiple births. However, despite existing policies, most patients request a transfer of more than one embryo. This is contrary to policy recommendations and thus an ethical dilemma for physicians (Ezugwu & S Van Der Burg 5).

CONCLUSION

In conclusion, the advent of assisted reproductive technologies has been and continues to be of great importance to the infertile population. Its adoption has been on the rise since 1978 when the first IVF baby was born. And though of great help to the infertile, there are potential risks associated with the process such as birth defects and multiple births. Some of these risks can however be reduced by enforcing strong policies and guidelines in IVF.

Works cited

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Chian, R-C. et al. “Obstetric Outcomes and Congenital Abnormalities in Infants Conceived with Oocytes Matured in Vitro.” Facts, Views & Vision in ObGyn 6.1 (2014): 15–18. Print.
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