Fertility treatments and use of hormones

What you'll learn

This revision guide covers how hormones control human reproduction and how medical science uses these hormones to help couples conceive or prevent pregnancy. You'll learn about the role of FSH and LH in the menstrual cycle, fertility treatments including IVF, and hormonal contraception methods. This content appears in Paper 2 of AQA GCSE Biology and is essential for questions on homeostasis and response.

Key terms and definitions

Fertility — the ability to conceive children naturally through sexual reproduction

FSH (follicle-stimulating hormone) — a hormone produced by the pituitary gland that causes eggs to mature in the ovaries and stimulates oestrogen production

LH (luteinising hormone) — a hormone released by the pituitary gland that triggers ovulation (release of a mature egg)

IVF (in vitro fertilisation) — a fertility treatment where eggs are fertilised by sperm outside the body in a laboratory, then implanted into the uterus

Contraception — methods used to prevent pregnancy from occurring

Ovulation — the release of a mature egg from an ovary, typically occurring around day 14 of the menstrual cycle

Infertility — the inability to conceive after regular unprotected sexual intercourse, affecting approximately 1 in 7 couples in the UK

Oral contraceptive — a pill containing hormones that prevents pregnancy, commonly called "the pill"

Core concepts

The role of hormones in fertility

The menstrual cycle is controlled by four key hormones working together in a carefully coordinated sequence. Understanding this sequence is essential for explaining how fertility treatments work.

FSH (follicle-stimulating hormone) is released from the pituitary gland at the start of the cycle. It has two main functions:

• Causes an egg to mature inside a follicle in one of the ovaries
• Stimulates the ovaries to produce oestrogen

Oestrogen is produced by the ovaries and:

• Causes the uterus lining to thicken in preparation for pregnancy
• Inhibits (stops) further FSH production
• Stimulates the pituitary gland to release LH

LH (luteinising hormone) is released by the pituitary gland around day 14 and:

• Triggers ovulation (release of the mature egg from the ovary)
• Stimulates the remains of the follicle to develop into the corpus luteum

Progesterone is produced by the corpus luteum after ovulation and:

• Maintains the thick uterus lining
• Inhibits FSH and LH release, preventing further eggs maturing

This hormonal cycle repeats approximately every 28 days if pregnancy does not occur. If pregnancy does occur, progesterone levels remain high to maintain the uterus lining throughout pregnancy.

Causes of infertility

Infertility can result from problems in either males or females. Common causes include:

Female infertility factors:

• Insufficient FSH production, meaning eggs do not mature properly
• Blocked fallopian tubes preventing egg and sperm meeting
• Irregular ovulation or failure to ovulate
• Problems with the uterus lining not developing properly

Male infertility factors:

• Low sperm count or poor sperm quality
• Sperm that cannot swim properly (low motility)
• Blocked sperm ducts

In the UK, approximately 1 in 7 couples experience difficulty conceiving. Age is a significant factor, with female fertility declining significantly after age 35 and male fertility also decreasing with age.

Fertility drugs and hormonal treatments

Fertility drugs work by manipulating the natural hormone cycle to increase the chances of successful conception.

FSH and LH treatment: Doctors can prescribe drugs containing FSH and LH to women who do not produce enough of these hormones naturally. The treatment works by:

• Providing artificial FSH to stimulate egg maturation in the ovaries
• Supplementing LH to trigger ovulation
• Causing several eggs to mature simultaneously, increasing conception chances

Advantages of fertility drugs:

• Non-invasive treatment (usually tablets or injections)
• Relatively inexpensive compared to other fertility treatments
• Allows natural conception through sexual intercourse
• Available on the NHS in many areas

Disadvantages of fertility drugs:

• Can result in multiple births (twins, triplets or more) because multiple eggs may be released
• Multiple pregnancies carry higher risks for mother and babies, including premature birth and low birth weight
• Success rates vary between individuals
• Side effects can include mood swings, headaches and nausea
• Does not guarantee pregnancy

The risk of multiple births is particularly significant. Whilst some couples may view twins as positive, carrying multiple babies increases medical risks substantially. Triplets or higher-order multiples require intensive neonatal care and carry significant health risks.

In vitro fertilisation (IVF)

IVF is a more complex fertility treatment used when other methods have failed or when there are specific fertility problems like blocked fallopian tubes.

The IVF process:

1. Hormone stimulation: The woman is given FSH and LH to stimulate multiple eggs to mature (usually 10-15 eggs)

2. Egg collection: Mature eggs are collected from the ovaries using a thin needle guided by ultrasound. This minor surgical procedure is performed under sedation

3. Fertilisation: The collected eggs are mixed with sperm from the partner or donor in a laboratory dish (the "in vitro" part means "in glass")

4. Embryo development: The fertilised eggs develop into embryos in controlled laboratory conditions for 3-5 days

5. Embryo transfer: One or two healthy embryos are selected and transferred into the woman's uterus through a thin tube inserted through the cervix

6. Implantation: If successful, an embryo implants into the uterus lining and pregnancy continues naturally

Advantages of IVF:

• Can work when other fertility treatments fail
• Effective for various causes of infertility including male factor infertility and blocked fallopian tubes
• Embryos can be screened for genetic conditions before implantation
• Unused embryos can be frozen for future use
• Success rates have improved significantly (around 25-30% per cycle for women under 35 in the UK)

Disadvantages of IVF:

• Expensive (£4,000-£8,000 per cycle privately in the UK)
• Limited NHS availability based on postcode lottery and eligibility criteria
• Physically and emotionally demanding process
• Success rate decreases significantly with maternal age (below 5% for women over 42)
• Multiple pregnancy risk if multiple embryos transferred
• Small risk of ovarian hyperstimulation syndrome from hormone treatment
• Ethical concerns for some people about unused embryos

Success factors in IVF: The success of IVF depends on several factors including maternal age (most important factor), cause of infertility, quality of embryos, and the clinic's expertise. Younger women have significantly higher success rates.

Hormonal contraception

Hormones can also be used to prevent pregnancy by disrupting the natural menstrual cycle.

The contraceptive pill: Oral contraceptives contain hormones that prevent pregnancy. Most common types include:

Combined pill — contains oestrogen and progesterone which:

• Inhibit FSH production, preventing egg maturation
• Prevent ovulation (no egg released means pregnancy cannot occur)
• Thicken cervical mucus, making it harder for sperm to reach any egg

Progesterone-only pill (mini pill) — contains only progesterone which:

• Thickens cervical mucus
• Thins the uterus lining
• Sometimes prevents ovulation

Advantages of hormonal contraception:

• Very effective when taken correctly (over 99% effective)
• Convenient and reversible
• Can reduce period pain and make periods more regular
• May reduce risk of certain cancers (ovarian and endometrial)
• Does not interrupt sexual activity

Disadvantages of hormonal contraception:

• Must be remembered daily (for pills)
• Does not protect against sexually transmitted infections (STIs)
• Possible side effects including headaches, nausea, mood changes, weight gain
• Small increased risk of blood clots, particularly in smokers over 35
• Not suitable for women with certain medical conditions
• Effectiveness reduced by some medications and by vomiting/diarrhoea

Other hormonal contraception methods:

• Contraceptive patch — releases hormones through the skin
• Contraceptive injection — progesterone injection lasting 8-13 weeks
• Contraceptive implant — small rod inserted under skin lasting 3 years
• Intrauterine system (IUS) — device releasing progesterone in the uterus

These methods have the advantage of not requiring daily attention but still carry similar side effects to oral contraceptives.

Non-hormonal contraception

For comparison, non-hormonal methods include:

• Barrier methods (condoms, diaphragm) — only condoms protect against STIs
• Intrauterine device (copper IUD) — prevents implantation
• Natural family planning — tracking fertile periods (less reliable)
• Sterilisation — permanent surgical procedure

Understanding both hormonal and non-hormonal methods helps explain the different mechanisms by which contraception works and allows for informed choices.

Evaluating fertility treatments

Exam questions often ask you to evaluate fertility treatments, weighing benefits against problems.

Social and ethical considerations:

Social issues:

• Fertility treatments, especially IVF, are expensive and not equally available to all
• NHS provision varies by region (postcode lottery)
• Multiple births from fertility treatments strain healthcare resources
• Age limits for treatment are controversial
• Emotional impact of failed treatments can be severe
• Some religious or cultural groups have concerns about certain treatments

Ethical issues:

• Status of embryos — when does life begin?
• Disposal of unused embryos in IVF
• Selection of embryos based on genetic characteristics
• Should there be age limits for treatment?
• Use of donor eggs or sperm
• Surrogacy arrangements

These considerations appear in extended response questions where you must present balanced arguments showing understanding of multiple perspectives.

Worked examples

Example 1: Explaining how fertility drugs work

Question: Explain how giving a woman FSH and LH as a fertility drug treatment increases the chance of pregnancy. (4 marks)

Mark scheme answer:

• FSH causes eggs to mature in the ovaries (1 mark)
• LH stimulates ovulation / release of eggs from the ovaries (1 mark)
• More eggs mature and are released than normal (1 mark)
• This increases the chance that one will be fertilised (1 mark)

Examiner note: The key is to explain the mechanism (what the hormones do) and link this to increased pregnancy chance. Simply stating "it makes pregnancy more likely" without explaining how would not gain full marks.

Example 2: Evaluating IVF treatment

Question: A couple are considering IVF treatment. Discuss the advantages and disadvantages of IVF. (6 marks)

Mark scheme answer:

Advantages:

• Can help couples who cannot conceive naturally to have children (1 mark)
• Works for various types of infertility including blocked fallopian tubes (1 mark)
• Embryos can be screened for genetic diseases before implantation (1 mark)

Disadvantages:

• Very expensive treatment that may not be available on NHS (1 mark)
• Low success rate, especially for older women / emotionally stressful (1 mark)
• Risk of multiple births which increases health risks for mother and babies (1 mark)

Examiner note: "Discuss" questions require you to present both sides. Aim for a balanced answer with roughly equal advantages and disadvantages. Use specific details rather than vague statements.

Example 3: Explaining contraceptive action

Question: The contraceptive pill contains oestrogen and progesterone. Explain how these hormones prevent pregnancy. (3 marks)

Mark scheme answer:

• The hormones inhibit / stop FSH production (1 mark)
• This prevents eggs from maturing in the ovaries (1 mark)
• No ovulation occurs / no egg is released so pregnancy cannot happen (1 mark)

Examiner note: You must explain the mechanism by which the hormones work. Stating only "they prevent pregnancy" would score zero marks. Follow the hormonal sequence logically.

Common mistakes and how to avoid them

• Confusing FSH and LH functions: Remember FSH causes maturation (FSH = Follicle Stimulating Hormone), whilst LH triggers release/ovulation. Make the distinction clear in your answers.

• Forgetting to explain mechanisms: When asked to explain, don't just state what happens — explain how and why. For example, don't just write "IVF helps infertile couples"; explain the actual process of egg collection, fertilisation, and embryo transfer.

• Only giving one side in evaluation questions: Questions using "discuss" or "evaluate" require balanced answers. Always provide both advantages and disadvantages with specific examples.

• Mixing up hormonal contraception methods: The combined pill contains oestrogen AND progesterone; the mini pill contains only progesterone. These work through slightly different mechanisms.

• Vague statements about success rates: Be specific where possible. State that IVF success decreases with age or that fertility drugs may cause multiple pregnancies rather than just saying "it might not work."

• Ignoring command words: "Describe" needs you to state what happens; "explain" requires you to say why/how it happens; "evaluate/discuss" needs both sides of an argument with a conclusion where appropriate.

Exam technique for "Fertility treatments and use of hormones"

• Identify command words carefully: "Explain" questions require you to give reasons or mechanisms (use words like "because," "this causes," "as a result"). "Describe" questions need you to state what happens without necessarily explaining why. "Discuss/evaluate" requires advantages AND disadvantages.

• Use correct terminology: Always use the full hormone names (FSH, LH, oestrogen, progesterone) rather than "hormones" alone. Use technical terms like "ovulation," "implantation," and "corpus luteum" where appropriate to demonstrate your knowledge.

• Link your knowledge to the context: If a question asks about helping couples conceive, explicitly link the biological process to successful pregnancy. If discussing contraception, link the mechanism to prevention of pregnancy.

• Calculate marks-per-point: A 4-mark question typically requires 4 separate points. If you've only written two sentences for 4 marks, you're likely missing content. Similarly, don't write excessively for 1-mark questions.

Quick revision summary

Fertility depends on the coordinated action of FSH, LH, oestrogen and progesterone controlling egg maturation and ovulation. FSH and LH fertility drugs increase egg production and release, improving conception chances but risking multiple births. IVF involves hormone stimulation, egg collection, laboratory fertilisation, and embryo transfer — effective but expensive with success declining with maternal age. Hormonal contraceptives contain oestrogen and/or progesterone to prevent ovulation by inhibiting FSH. Fertility treatments raise social and ethical issues around cost, access, and embryo status that you must evaluate in exam questions.