Pregnancy Prevention
Senior 2 · Biology
Pregnancy Prevention
Lesson 1 of 4
20 min
Every family in Rwanda has an opinion about family planning, and not all of those opinions are based on facts. You will hear that the pill makes women infertile, that a girl cannot get pregnant the first time, or that washing after sex prevents pregnancy. None of these is true. This unit gives you accurate biology, so that as an adult you can make informed decisions, and so that you can correct myths when you hear them.
For you as a secondary school student, the key fact is simple: abstinence is the only method that is 100% effective at preventing pregnancy, and it also protects you from sexually transmitted infections.
Contra means "against", so contraception means "against conception": any method used to prevent pregnancy. Each method breaks the chain above at one point: it stops an egg being released, stops sperm reaching the egg, or stops a fertilised egg implanting. Methods are grouped as:
A method's failure rate is the number of women out of 100 who become pregnant during one year of using it. Typical use rates include ordinary human mistakes such as forgetting a pill, so they are higher than perfect use rates.
| Method | Pregnancies per 100 women in one year of typical use |
|---|---|
| Implant | fewer than 1 |
| Sterilisation | fewer than 1 |
| Injection | 3 |
| Pill, patch or vaginal ring | 8 |
| Natural family planning | 12 to 25 |
| Barrier methods (condoms, diaphragm and others) | 15 to 24 |
| Withdrawal (pulling out before ejaculation) | 27 |
| Abstinence | 0 |
In a sector, 300 women use the pill and 300 use an implant for one year. Estimate the number of pregnancies in each group, and explain the difference.
| Myth | Fact |
|---|---|
| A girl cannot get pregnant the first time she has sex. | False. Pregnancy can happen whenever sperm meet an egg, including the very first time. |
| You cannot get pregnant during your period. | False. It is less likely, but sperm can survive for up to five days, and in a short cycle ovulation may come soon after bleeding ends. |
| Washing or urinating after sex prevents pregnancy. | False. Sperm enter the cervix within minutes; washing cannot reach them. |
| Withdrawal is a safe method. | False. Sperm can be released before ejaculation, and about 27 in 100 couples relying on withdrawal have a pregnancy within a year. |
| The pill or the injection makes a woman permanently infertile. | False. Fertility returns after stopping a reversible method, though after the injection it may take several months. |
| The pill protects against HIV. | False. Only condoms protect against sexually transmitted infections. |
| Family planning is only the woman's responsibility. | False. Both partners share the decision. Condoms and vasectomy are methods used by men. |
Tip
Every method breaks the chain at one link: no egg released (hormones), no meeting of sperm and egg (barriers, natural methods, copper IUD, sterilisation), or no implantation.
For calculations: expected pregnancies = failure rate × (number of women ÷ 100).
What does "contraception" mean, and where does the word come from?
Answer: Contraception is any method used to prevent pregnancy. The word comes from "contra" (against) and "conception" (becoming pregnant).
Using the table, how many of 500 couples relying on withdrawal for a year would you expect to have a pregnancy?
Answer: 27 × (500 ÷ 100) = 27 × 5 = 135 pregnancies.
Explain why typical-use failure rates are higher than perfect-use failure rates.
Answer: Typical use includes human mistakes: forgetting pills, being late for an injection, not using a condom every time or using it incorrectly. Perfect use assumes the method is always used exactly as instructed.
A friend says she cannot get pregnant because it is her first time. Correct her using biology.
Answer: If she has already begun ovulating, an egg may be present. Sperm can fertilise it whether or not it is the first time, so pregnancy is possible.
Remember
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