Pregnancy Prevention
Senior 2 · Biology
Pregnancy Prevention
Lesson 3 of 4
22 min
Barrier and hormonal methods are the ones most couples use. Injectables and implants are among the most widely used methods in Rwanda, and condoms are the only method that protects against both pregnancy and HIV. Knowing exactly how each one works explains why some fail more often than others, and why the right choice depends on each person's needs.
Condoms must be used correctly every time, from start to finish. Use a new condom each time, check the expiry date, open the packet carefully without teeth or scissors, and never use two at once, because friction can tear them. Most condom "failures" are really times when a condom was not used, or was used wrongly.
Dual protection: male and female condoms are the only contraceptives that also protect against sexually transmitted infections, including HIV. Many couples combine a condom with another method, such as an implant, to protect against both pregnancy and infection.
Hormonal methods contain man-made versions of the female sex hormones oestrogen and progesterone (the man-made forms of progesterone are called progestogens). They work in three ways:
| Method | How it is used | Typical-use failure (per 100 women per year) |
|---|---|---|
| Combined pill | A tablet containing oestrogen and progestogen, taken every day | 8 |
| Progestogen-only pill | A tablet taken every day at the same time | about 8 |
| Injection | An injection of progestogen, usually every three months | 3 |
| Implant | One or two small flexible rods placed under the skin of the upper arm by a trained health worker; they work for 3 to 5 years | fewer than 1 |
| Patch and vaginal ring | Release hormones through the skin or the vaginal wall; changed weekly or monthly | 8 |
Possible side effects include irregular or no bleeding, headaches, nausea and changes in weight. They usually settle within a few months. A health worker checks each person's health before prescribing, because a few conditions make some methods unsuitable. Fertility returns after stopping; after the injection this may take several months.
Emergency contraception is a pill taken as soon as possible after unprotected intercourse, or after a condom breaks. It works best within 72 hours. It mainly delays ovulation, so it cannot end a pregnancy that has already begun, and it is less effective than regular methods, so it is for emergencies only.
No hormonal method protects against STIs or HIV.
For each person, choose a suitable method and give the reason.
Tip
Barriers block, hormones stop the egg. Barrier methods stop sperm reaching the egg; hormonal methods mainly stop ovulation and thicken cervical mucus.
Only condoms give dual protection against both pregnancy and STIs, including HIV.
Explain two ways in which the combined pill prevents pregnancy.
Answer: Its hormones stop the pituitary releasing the surges of FSH and LH that trigger ovulation, so no egg is released; and they thicken the cervical mucus so that sperm cannot pass through. They also keep the uterus lining thin.
Why is the implant more effective than the pill in typical use?
Answer: The pill must be taken correctly every day, and missed pills cause most failures. The implant releases hormone continuously for years with nothing for the user to remember, so typical use is almost the same as perfect use.
State two rules for using a male condom correctly.
Answer: Any two of: use a new condom every time; put it on before any contact; check the expiry date and that the packet is undamaged; open the packet carefully without teeth or scissors; never use two condoms at once.
Why is emergency contraception not used as a regular method?
Answer: It is less effective than regular methods, it must be taken within a short time after intercourse, and repeated use can cause irregular bleeding. Regular methods give better, steadier protection.
Remember
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