Contraception (AQA GCSE Biology Combined Science): Revision Notes
Contraception
Contraception helps people control when they have babies. There are different ways to prevent pregnancy, using both hormonal and non-hormonal methods. Understanding these options allows individuals to make informed decisions about family planning based on their personal needs, health considerations, and lifestyle preferences.
Each contraceptive method works differently and has its own advantages and considerations. The effectiveness of contraception depends on correct and consistent use.
Oral contraceptives (the pill)
How they work
Birth control pills contain hormones called oestrogen and progesterone. These hormones stop the brain from releasing FSH (follicle stimulating hormone). This creates a cascade effect that prevents pregnancy through multiple mechanisms.
How Hormonal Contraception Works:
Step 1: The pill releases synthetic oestrogen and progesterone into the bloodstream
Step 2: These hormones signal the brain to stop producing FSH
Step 3: Without FSH, the following occurs:
- Eggs don't develop properly in the ovaries
- No eggs are released during the monthly cycle
- Pregnancy cannot happen
Side effects
While the pill is generally safe and effective, taking hormonal contraceptives can cause some health considerations that users should be aware of.
Potential Side Effects to Monitor:
- Higher blood pressure
- Blood clots (thrombosis)
- Small increased risk of breast cancer
Always discuss your medical history with a healthcare provider before starting hormonal contraception.
The newer pills contain less oestrogen, which makes them safer with fewer side effects compared to earlier formulations.
Surgical methods
Surgical contraception involves permanent procedures that prevent pregnancy by interrupting the reproductive process. These methods are considered permanent solutions and require careful consideration.
For women - sterilisation
A doctor blocks or cuts the fallopian tubes that carry eggs from the ovaries to the womb. This stops eggs from meeting sperm. Women still have normal periods after this operation since hormone production continues normally.
For men - vasectomy
A doctor cuts the vas deferens - the tubes that carry sperm from the testicles. This stops sperm from getting into the semen when a man ejaculates.
Critical Considerations for Surgical Methods:
- Both operations are very difficult to reverse
- People need to use other contraception for a few months after surgery
- These are permanent solutions
- Success rates are very high (over 99% effective)
- Recovery time varies but is generally quick for both procedures
Barrier methods
These methods work by creating a physical barrier that prevents sperm from reaching an egg. They are non-hormonal options that can be used as needed.
Condoms - thin rubber sheaths that go over the penis to collect semen during ejaculation
Diaphragms - thin rubber caps that cover the woman's cervix (entrance to the womb)
Enhancing Barrier Method Effectiveness:
Both methods work better when used with spermicide - a chemical that kills or damages sperm. If the barrier breaks or is used incorrectly, the spermicide provides extra protection as a backup mechanism.
Proper use is essential - this includes checking for damage before use, correct placement, and leaving the barrier in place for the recommended time after intercourse.
Other methods
IUD (intrauterine device)
This is a small T-shaped object made of plastic and copper that provides long-term contraceptive protection. A trained healthcare provider places it inside the womb during a medical procedure.
How IUDs Prevent Pregnancy:
The IUD works through multiple mechanisms:
- Stops sperm and eggs from surviving in the womb environment
- The copper creates conditions toxic to sperm
- May prevent a fertilised egg from implanting in the womb lining
- Can be removed to restore normal fertility when pregnancy is desired
- Effective for several years depending on the type
Natural family planning
Some couples avoid having sex during the woman's fertile time each month. They work out when an egg might be released by tracking various fertility signs and avoid intercourse during that window.
This method requires careful monitoring of body temperature, cervical mucus changes, and menstrual cycle patterns. It's most effective when couples receive proper training and are committed to consistent tracking.
Summary
Key Points to Remember:
- Hormonal contraceptives (like the pill) stop eggs from being released by blocking FSH production
- Surgical methods are permanent but very effective - vasectomy for men, sterilisation for women
- Barrier methods physically stop sperm reaching eggs and work better with spermicide
- IUDs prevent pregnancy by creating unsuitable conditions in the womb for several years
- Natural family planning requires careful timing and tracking to avoid fertile periods
- Each method has different effectiveness rates, side effects, and suitability for different individuals