Assisted Reproductive Technology

This lesson covers how hormones and medical technology can be used to help people who have difficulty conceiving. The Edexcel GCSE Biology (1BI0) specification requires you to understand in vitro fertilisation (IVF), the use of clomifene to stimulate ovulation, and the ethical issues surrounding fertility treatment.

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Why Might Fertility Treatment Be Needed?

Some couples have difficulty conceiving naturally. Causes of infertility include:

Cause	Detail
Failure to ovulate	The ovaries do not release eggs regularly (may be due to hormonal imbalance)
Blocked oviducts	The fallopian tubes are blocked or damaged, preventing egg and sperm from meeting
Low sperm count	The male partner produces too few sperm, or sperm with poor motility
Endometriosis	Uterus lining tissue grows outside the uterus, causing scarring
Age	Female fertility declines significantly after age 35
Unexplained infertility	No identifiable medical cause

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Clomifene Therapy

Clomifene (also called clomiphene) is a drug used to treat infertility in women who are not ovulating regularly.

How Clomifene Works

1. Clomifene blocks oestrogen receptors in the brain (specifically in the hypothalamus and pituitary gland).
2. Because the brain cannot detect oestrogen, it "thinks" oestrogen levels are low.
3. This removes the negative feedback effect of oestrogen on the pituitary gland.
4. The pituitary gland responds by releasing more FSH (and LH).
5. The increased FSH stimulates the ovaries to develop follicles and mature eggs.
6. This increases the chance of ovulation occurring.

Exam Tip: Clomifene works by interfering with negative feedback. It blocks oestrogen receptors at the pituitary → pituitary cannot detect oestrogen → pituitary releases more FSH → follicles develop → ovulation is more likely. This is a common 4-mark question.

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In Vitro Fertilisation (IVF)

In vitro fertilisation (IVF) literally means "fertilisation in glass." It is a procedure where fertilisation takes place outside the body in a laboratory.

The IVF Process — Step by Step

Step	What Happens
1. Hormone stimulation	The woman is given FSH and LH by injection to stimulate the ovaries to produce several mature eggs at once (rather than the usual one)
2. Egg collection	The mature eggs are collected from the ovaries using a fine needle guided by ultrasound
3. Fertilisation	The collected eggs are mixed with sperm from the male partner (or a donor) in a laboratory dish. Fertilisation occurs outside the body
4. Embryo development	The fertilised eggs develop into embryos in the laboratory for 2–3 days (sometimes up to 5–6 days to the blastocyst stage)
5. Embryo transfer	One or two of the healthiest embryos are selected and transferred into the woman's uterus using a thin catheter
6. Waiting	The woman waits approximately two weeks to see if the embryo has implanted in the uterus lining (confirmed by a pregnancy test)

Success Rates

• IVF success rates are approximately 25–30% per cycle on average.
• Success rates decrease with age: women under 35 have higher success rates than women over 40.
• Multiple cycles may be needed, increasing the overall cost and emotional burden.

Exam Tip: When describing the IVF process, always mention: (1) hormones given to stimulate multiple eggs, (2) eggs collected, (3) fertilised with sperm in a dish, (4) embryo develops in lab, (5) embryo transferred to uterus. This five-step sequence is what examiners are looking for.

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Ethical, Social, and Emotional Issues with IVF

IVF is a powerful technology, but it raises significant ethical and social concerns. You may be asked to discuss these in an exam.

Arguments in Favour of IVF

Argument	Explanation
Helps infertile couples	Gives people who cannot conceive naturally the chance to have a biological child
Medical screening	Embryos can be screened for genetic disorders before implantation (pre-implantation genetic diagnosis)
Donor options	Donor eggs or sperm can be used if one partner cannot produce viable gametes
Scientific advancement	IVF research has improved understanding of human reproduction and genetics

Arguments Against IVF

Argument	Explanation
Unused embryos	Embryos that are not implanted may be frozen, donated, or destroyed. Some people believe this is ethically wrong, as they consider the embryo a potential life
Multiple births	If more than one embryo is transferred, there is a higher risk of twins or triplets, which carries health risks for the mother and babies (premature birth, low birth weight)
Emotional stress	The process is emotionally demanding, especially if cycles are unsuccessful
Financial cost	IVF is expensive (several thousand pounds per cycle), and NHS funding is limited. This raises concerns about fairness and access
Physical side effects	Hormone injections can cause side effects such as mood swings, bloating, and in rare cases ovarian hyperstimulation syndrome (OHSS)
Low success rate	With only ~25–30% success per cycle, many couples go through multiple rounds without success

Exam Tip: Ethical questions are common in 6-mark extended response questions. Always give both sides of the argument and use specific examples. Conclude by stating that it is a personal decision and that different people may have different views based on their beliefs.

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IVF and Hormones — Connecting to the Menstrual Cycle

IVF relies on the same hormones studied in the menstrual cycle lesson:

Hormone Used	Role in IVF
FSH	Stimulates the ovaries to mature multiple eggs at once (superovulation)
LH	Works alongside FSH to trigger the final maturation and release of eggs
Progesterone	Sometimes given after embryo transfer to help maintain the uterus lining

The woman's natural cycle may first be suppressed using drugs, and then FSH and LH are given by injection to control the exact timing of egg maturation and collection.

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When Is Fertility Treatment Considered?

Fertility treatment may be considered when:

• A couple has been trying to conceive for over a year without success.
• There is a known medical cause of infertility (e.g. blocked oviducts, low sperm count).
• The woman is not ovulating and clomifene or other medications have not worked.
• Other treatments have been unsuccessful.

The choice of treatment depends on the cause of infertility:

• Not ovulating → clomifene therapy (first-line), then IVF if unsuccessful.
• Blocked oviducts → IVF (bypasses the oviducts entirely).
• Low sperm count → IVF with a technique called ICSI (intracytoplasmic sperm injection), where a single sperm is injected directly into the egg.

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Summary