Reproductive Technology

In my last post, I spoke about contraception- ways to prevent pregnancy. In this post, I'm going to talk about ways to induce pregnancy in cases where the man and woman can't reproduce naturally. This can occur for many reasons, some due to sterility in the man, some due to sterility in the woman, and some due to a mix of both.

In some cases, infertility can be treated- for example, blocked oviducts and sperm ducts can be opened and tumours can be removed. Cervical mucus hostile to sperm can be treated. If the cause of infertility is untreatable, the couple may opt to use reproductive technology instead. In this post, I'll give a run-down on some of the techniques used, as well as similar technologies such as cloning. Like all posts before this, nothing here is intended to be medical advice.

Artificial Insemination by Donor (AID)

Artificial insemination by donor, or AID, involves the woman accepting semen donated by an unknown man. Attempts are made to choose semen from a donor with physical characteristics similar to that of the woman's husband. Around the time of ovulation, the donor's semen is injected into the upper vagina of the woman once each day for 3-4 consecutive days (that sounds painful to me, but then again I hate needles). This has a success rate of around 70-80%, but normally requires at least 3 months to work. It is rare that pregnancy will occur after the first round of AID. (This means more needles... ugh. Never mind, I've never wanted kids anyway, so even if I do turn out to be infertile, I'll never make myself go through this.)

It is also possible to remove the sperm from a man who has just died and freeze it, so that they can be used later for AID. Very few people have chosen to do so, however.

Risks in AID involve possible transmission of disease from the donor to the recipient. Hence, donors are carefully screened for health problems.

Assisted Reproductive Technology (ART)

There are several different forms of ART, all of which involve the fertilisation of an egg and sperm outside of the uterus. The resulting embryo is then transplanted into the woman's uterus. Most of these techniques require the woman to take fertility medication to increase the number of eggs that are produced by her ovaries.

Here are some techniques used in ART:

• In vitro fertilisation (IVF)- The ovum is taken from the mother, fertilised outside the body, and transplanted back into the uterus.
• Gamete intrafallopian transfer (GIFT)- The eggs and sperm are mixed together immediately after the eggs have been collected before being injected into the woman's uterine tubes. The eggs and sperm will mix naturally in the uterine tubes before hopefully fertilising. Success rates are relatively low.
• Zygote intrafallopian transfer (ZIFT)- The eggs are fertilised in the lab. At the zygote stage, normally a day after fertilisation, the zygote is transferred to the woman's uterine tubes. This requires two operations- one two obtain the eggs, and one to place the zygote in the uterine tubes. Some doctors feel that the success rate is not high enough to justify the risks of two operations.
• Tubal embryo transfer (TET)- Very similar to ZIFT, but the fertilised eggs divide more (to the 2-cell to 4-cell stage) before being implanted into the woman's uterine tubes.
• Intracytoplasmic sperm injection (ICSI)- A single sperm is injected into a single egg through a micro-pipette and the embryo is transplanted into the woman's uterus. Fertilisation rates are around 20-30%, but there may be an increased insidence of birth defects.
• Donor egg- The man's sperm is mixed with an egg from a donor, and the resulting embryo is placed into the woman's uterus. (I nearly typed "mixed with a donated woman's egg" in there. Thankfully, I noticed that in time.)
• Donor embryo- A donated embryo is implanted into the woman's uterus.

ART technology has advanced in many ways. There are procedures to make the uterine cavity more suitable for implantation and procedures to allow the embryos to develop for a longer period before implantation, allowing more time to determine the most suitable embryo. A technique called preimplantation genetic diagnosis (PGD) can be used to test embryos for genetic defects, but it is banned in some places due to ethical issues.

There are ethical issues involved in ART. One such issue involves excess embryos. Often, more embryos are available than are needed. Embryos can be frozen and stored for 5 years, after which parents are asked if they would like them thawed and implanted, donated to others, thawed and disposed, or experimented on. The last three options all raise ethical issues, especially experimentation.

Surrogacy

In some cases where the woman has been unable to become pregnant, the couple may pay another woman, known as the surrogate mother, to bear a child for them. The man may provide semen naturally or through artificial insemination. Another method involves taking the woman's egg and the man's sperm, allowing fertilisation to occur outside the body using one of the ART techniques, and implanting the resulting embryo into the surrogate mother's body.

Surrogacy can cause many legal issues if the surrogate mother decides that she wants to keep the child. Normally, the courts will support the surrogate mother.

Cloning

Cloning isn't considered a form of reproductive technology as there are ethical guidelines against producing multiple genetically identical humans, but the technology has some similarities. The most famous clone is perhaps Dolly the sheep, the first animal clone, born from the fertilisation of a body cell from an adult female sheep with an unfertilised egg with the nucleus removed.

Aside from cloning whole animals or humans, research is being done into "therapeutic cloning," or the use of cloning techniques to grow organs. This can be used to replace organs damaged by diseases. However, human stem cells, which are as-yet undifferentiated cells that can later differentiate into different types of cells, are required for this research. Since these cells can only be obtained from embryos, destroying the embryo in the process, there are a lot of ethical issues surrounding stem cell research. Some countries have strict guidelines which prevent the production of human embryonic stem cells.

Cloning does appear to have some adverse effects in some clones. For example, Dolly the sheep had inherited, in some respects, the age of the cells from which she had been created, leading her to age younger. Cloned mice, however, have not been found to suffer the effects of premature ageing, which raises all sorts of new questions for scientists studying cloning.

One potential benefit of cloning is to increase the population of severely endangered species. It could potentially be used to help couples unable to have a child via any other means, but there is strong resistance to this idea for a variety of ethical reasons.

Next up: STDs. After the next chapter I can finally get off this topic! Yay!