UK GCSE level age ~14-16, ~US grades 9-10 Biology revision notes re-edit 19/05/2023 [SEARCH]

 Human sexual reproduction: 7. Methods of increasing fertility, increasing the chance of pregnancy, hormone treatment, IVF, insemination

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INDEX of biology notes on human sexual reproduction


(7) Methods of increasing fertility - increasing the chance of pregnancy

This is the complete opposite of contraception.

The desire for children is a very powerful motivation in human nature but to be infertile means you cannot reproduce naturally.

Unfortunately some women are infertile, unable to get pregnant and reproduce naturally, but, help is at hand from various hormonal treatments to greatly improve their fertility and ultimately deliver a baby.

Hormones are a key factor in fertility, and can be used to increase fertility - to increase the chance of pregnancy.

Using hormones to increase fertility

Some women have too low a level of FSH (follicle-stimulating hormone) to stimulate the eggs to mature in the ovary. Therefore no ovulation, no eggs are released and pregnancy cannot happen.

FSH and LH (luteinising hormone) can be administered as a fertility drug to stimulate ovulation.

The method obviously improves fertility - the chances of getting pregnant, but there are 'negatives'.

(i) The treatment is expensive and doesn't always work.

(ii) Sometimes too many eggs are stimulated at the same time resulting in multiple pregnancies e.g. twins or triplets.

Women can be infertile due to lack of ovulation (none or irregular ovulation), so another similar approach is to use the medication clomifene therapy (clomiphene).

Clomifene (clomiphene) works by causing more FSH and LH to be released by the body - this in turn stimulates eggs to mature and be released (ovulation).

If you know when the woman is more likely to ovulate, a couple can have intercourse during the treatment period to increase the chances of the woman becoming pregnant.

However, there are some unpleasant side effects from using clomifene e.g. pelvic pain and hot flushes.


IVF treatment - In Vitro Fertilisation

What is IVF?

IVF stands for 'In Vitro Fertilisation', is an option for treating infertility in which eggs are fertilised outside the woman's body by sperm from the father.

Why choice of IVF?

Sometimes giving FSH and LH in a ‘fertility drug’ to a woman whose own level of FSH is too low to stimulate eggs to mature doesn't always work.

If women are unable to get pregnant with hormonal treatment they may try IVF treatment.

IVF is an example of Assisted Reproductive Technology (ART), defined as a fertility treatment involving the handling of eggs (usually fertilised) outside of the body.

The IVF procedure

IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs where they would not have been released - this must be done before egg collection, and it also means more than one egg can be collected.

In IVF treatment, after the potential mother has been treated with FSH and LH, eggs are collected from her ovaries and fertilised in the laboratory by sperm from the father.

The mixture is monitored microscopically, over a period of 16-20 hours, to look for successful fertilisation.

IVF treatment can also involve a technique called Intra-Cytoplasmic Sperm Injection (ICSI), where the sperm is directly injected into an egg.

This may be applied if the sperm count of the man is low.

In either case, in a laboratory, the fertilised eggs grow and develop into embryos in a incubator.

At the stage when the fertilised eggs are just tiny balls of cells (~100), one or two embryos are inserted into the mother’s uterus (womb) to attempt a pregnancy.

The initial success rate is not that high, 20-30% of each cycle of treatment

The chance of pregnancy decreases with each successive round and the cost increases too.

However, the cumulative effect of three full cycles of IVF treatment can give an over 45% chance of pregnancy.

IVF techniques are more successful if the woman has (i) been pregnant before, (ii) younger, (ii) has a BMI of between 10 and 30, (iv) has a low alcohol and caffeine intake and doesn't smoke.

Advantages and disadvantages of IVF treatment - the 'pros and cons'

Some women, for various medical reasons, cannot conceive in the conventional way.

BUT, IVF has enabled many mothers to get pregnant and give birth to healthy children - a wonderful application of medical science and technology.

BUT it doesn't always work for an infertile couple and there other downsides too.

About half of the embryos produced by IVF have an incorrect number of chromosomes - genetically defective.

Also, about 1/3rd of the normal embryos selected, will not implant in the uterus.

Sadly, tragically, there are raised incidences of premature births, stillbirths, low birth-weights and infant deaths.

It is possible for several eggs to be simultaneously matured resulting in multiple pregnancies eg twins, triplets and more develop from the growth of more than one embryo into a baby!

This increases the risk for mother and babies - multiple pregnancy puts extra strain on the mother - there is an increased risk of an unsuccessful birth e.g. miscarriage or stillbirth.

IVF has a low success rate, averaging 26% in the UK. It ranges from 29% for women under 35, down to 23% or less for women over 35. Age is an important factor and fertility decreases as a woman gets older.

This low success rate makes the whole process very stressful both physically and mentally - the situation is emotionally draining, especially if IVF treatment fails several times.

Women can suffer side-effects from the hormone treatment which can be physically and emotionally demanding e.g. abdominal pain, dehydration, vomiting - an overlap of side effect symptoms from hormonal contraception

BUT, most infertile couples would regard IVF treatment is worth the risk.

Advances in IVF techniques

Microscope techniques have become more advanced and improved the success rate of IVF fertility treatment.

This involves using special micro-tools to manipulate sperm and eggs under the microscope.

You can now remove single cells from the embryo for genetic testing to check if the genome will facilitate a healthy embryo-baby.

With a microscope and camera, you can also use time lapse imaging of the embryo growing in the incubator, allowing you to continuously monitor the growth of the embryos to see which are the most likely to result in a successful pregnancy


Objections to IVF treatments - ethical issues

Most objections centre around the ethical issues of IVF.

(i) IVF procedures often result in unused embryos being destroyed and some people consider this unethical - immoral, because you have destroyed a potential human life.

Is right that the bundle of cells of the embryo are arbitrarily used or discarded? and destroyed.

Are the inevitable losses of potential life, albeit genetically defective, worth the price of successfully developed embryos?

(ii) The genetics and genetic testing of embryos before implantation in the mother's womb raises the ethical issue of preferential choice of characteristics of the baby e.g. choice of gender, eye colour or even whether you allow a child to be born with disabilities.

With advances in microscopic and genetic techniques it is possible to screen the embryos for abnormalities e.g. genetic defects, this means we are making a life or death decision on the test outcome.

Couples, where one is a normal fertile women, could use IVF to select, and allow/not allow to develop, a child with particular characteristics e.g. sex. Many would regards this as unethical and a misuse of IVF.

(iii) Some people consider that IVF as just getting round natural obstacles to getting pregnant

But IVF is not natural, and some consider it unnatural, because it replaces the physical and emotional relationship of conceiving by intercourse with a 'synthetic' laboratory technique.


Evaluation of IVF

You might be expected to evaluate the benefits of, and the problems that may arise from, the use of hormones to control fertility, including In Vitro Fertilisation (IVF) and might be given information data to work on.

Artificial insemination (AI)

AI, also known as intrauterine insemination (IUI), is a fertility treatment that involves directly inserting sperm into the woman's womb.

You need a sperm donor, a 'partner' (known father) or frozen sperm from a sperm bank (anonymous father)..



INDEX of biology notes on human sexual reproduction


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