Hormonal and Non-Hormonal Contraception
This lesson covers the different methods of contraception required by Edexcel GCSE Biology (1BI0) Topic 7. You need to understand how hormonal methods work by manipulating the menstrual cycle hormones, as well as the range of non-hormonal methods available. You must also be able to evaluate the advantages and disadvantages of each.
What Is Contraception?
Contraception is the deliberate prevention of pregnancy. Methods of contraception can be broadly divided into two categories:
- Hormonal methods — use synthetic hormones to prevent pregnancy.
- Non-hormonal methods — use physical barriers, chemicals, or other techniques.
Hormonal Methods of Contraception
Hormonal contraceptives work by introducing synthetic versions of oestrogen and/or progesterone into the body. These hormones interfere with the normal menstrual cycle to prevent pregnancy.
1. The Combined Pill
- Contains synthetic oestrogen and progesterone.
- How it works: The oestrogen in the pill inhibits FSH production by the pituitary gland. Without FSH, no follicle develops and no egg matures. Progesterone also thickens cervical mucus and thins the uterus lining.
- Taken daily for 21 days, followed by a 7-day break.
| Advantages | Disadvantages |
|---|
| Over 99% effective when used correctly | Must be taken at the same time every day |
| Can make periods lighter and more regular | Does not protect against STIs |
| Can be stopped at any time to restore fertility | Can cause side effects (headaches, nausea, mood changes) |
| Reduces risk of some cancers (ovarian, endometrial) | Small increased risk of blood clots and breast cancer |
2. The Progesterone-Only Pill (Mini Pill)
- Contains only progesterone (no oestrogen).
- How it works: Progesterone thickens the cervical mucus, making it difficult for sperm to reach the egg. It may also thin the uterus lining and, in some cases, inhibit ovulation.
- Taken every day with no break.
| Advantages | Disadvantages |
|---|
| Suitable for women who cannot take oestrogen | Must be taken at a very precise time each day |
| Fewer side effects than the combined pill | May cause irregular periods or spotting |
| Can be used while breastfeeding | Does not protect against STIs |
3. The Contraceptive Injection
- Contains progesterone that is injected and released slowly over 8–13 weeks (depending on the type).
- How it works: Prevents ovulation, thickens cervical mucus, and thins the uterus lining.
| Advantages | Disadvantages |
|---|
| Long-lasting (no daily pill to remember) | Cannot be reversed once injected; must wait for it to wear off |
| Over 99% effective | May cause weight gain, headaches, or irregular bleeding |
| Does not protect against STIs |
| Fertility may take several months to return after stopping |
4. The Contraceptive Implant
- A small, flexible rod inserted under the skin of the upper arm.
- Releases progesterone slowly for up to 3 years.
- How it works: Same as the injection — prevents ovulation, thickens cervical mucus, thins uterus lining.
| Advantages | Disadvantages |
|---|
| Over 99% effective | Requires a minor procedure to fit and remove |
| Lasts up to 3 years | May cause irregular bleeding, especially initially |
| Once removed, fertility returns quickly | Does not protect against STIs |
5. Intrauterine System (IUS)
- A small T-shaped device inserted into the uterus that releases progesterone for 3–5 years.
- Thickens cervical mucus, thins the uterus lining, and may prevent ovulation.
| Advantages | Disadvantages |
|---|
| Very effective (over 99%) | Requires fitting by a medical professional |
| Long-lasting (3–5 years) | Can cause discomfort during fitting |
| Can make periods lighter or stop them | Does not protect against STIs |
Exam Tip: All hormonal methods work by using progesterone and/or oestrogen to interfere with the menstrual cycle. The combined pill is the only common method that contains oestrogen — most other hormonal methods use progesterone only.
Non-Hormonal Methods of Contraception
These methods do not involve hormones. They prevent pregnancy by creating a physical barrier, killing sperm, or preventing implantation.
1. Male Condom
- A thin sheath worn over the penis during intercourse.
- Barrier method: physically prevents sperm from reaching the egg.
| Advantages | Disadvantages |
|---|
| Protects against STIs (the only widely used method that does) | Can split or slip off if not used correctly |
| No hormonal side effects | Must be used every time |
| Easy to obtain, widely available | Some people find them less comfortable |
| ~98% effective when used correctly | |
2. Female Condom
- A soft pouch inserted into the vagina before intercourse.
- Also a barrier method that prevents sperm reaching the egg.
| Advantages | Disadvantages |
|---|
| Protects against STIs | Less widely available than male condoms |
| No hormonal side effects | Can be less effective (~95%) |
| Woman-controlled | Can be more difficult to use |
3. Diaphragm (or Cap)
- A dome-shaped device placed over the cervix before intercourse to block sperm.
- Usually used with spermicide for increased effectiveness.
| Advantages | Disadvantages |
|---|
| No hormonal side effects | Must be inserted before intercourse and left in for several hours |
| Reusable | Less effective than hormonal methods (~92–96%) |
| Does not protect against STIs |
4. Intrauterine Device (IUD) — The Copper Coil
- A small T-shaped device inserted into the uterus, wrapped in copper.
- How it works: The copper releases copper ions that are toxic to sperm. It also causes a mild inflammatory reaction in the uterus that prevents implantation.
- Lasts 5–10 years.
| Advantages | Disadvantages |
|---|
| Very effective (over 99%) | Can cause heavier or more painful periods |
| Long-lasting; no daily action needed | Requires fitting and removal by a professional |
| Non-hormonal | Does not protect against STIs |
| Fertility returns immediately after removal | |
5. Spermicide
- A chemical substance (cream, gel, or foam) that kills or immobilises sperm.
- Usually used alongside another method (e.g. diaphragm or condom) for greater effectiveness.
| Advantages | Disadvantages |
|---|
| Non-hormonal | Not very effective when used alone (~72–86%) |
| Easy to use | Must be applied before intercourse |
| Does not protect against STIs |
6. Natural Family Planning
- Involves monitoring body temperature, cervical mucus, and the menstrual cycle to identify fertile days and avoid intercourse on those days.
| Advantages | Disadvantages |
|---|
| No chemicals, hormones, or devices | Requires careful daily monitoring |
| No side effects | Less reliable (~76–88% effective in typical use) |
| Acceptable to all religious groups | Does not protect against STIs |
| Irregular cycles make it harder to predict fertile days |
7. Surgical Methods
Vasectomy (males): The vas deferens (tubes carrying sperm) are cut or sealed. Sperm can no longer leave the body during ejaculation.
Female sterilisation: The oviducts (fallopian tubes) are cut, clipped, or sealed. Eggs can no longer travel to the uterus or meet sperm.
| Advantages | Disadvantages |
|---|
| Over 99% effective | Considered permanent (reversal is difficult and not always successful) |
| No ongoing action required | Requires surgery |
| No hormonal side effects | Does not protect against STIs |