5 Safe sex: what’s that? MENSTRUAL CYCLE The menstrual cycle lasts roughly four weeks. For every girl it’s different. For some longer, for others shorter. To know how to prevent pregnancy, you need to know how the menstrual cycle works. This also shows how you become pregnant. And how do you prevent that? By using a contraceptive. WEEK 4 The egg degenerates • If fertilisation doesn’t occur within two days, the mature egg degenerates. • The uterus gets ready to release its lining. WEEK 1 WEEK 4 WEEK 1 Your period • If the egg isn’t fertilised, the body releases it, together with the lining of the uterus. That’s why there’s bleeding. This is called menstruation – your period. • A girl menstruates for roughly four to seven days. Egg WEEK 3 Ovulation • When the egg has ripened, it is released from the ovary into the fallopian tube. This is ovulation. WEEK 2 Egg ripens WEEK 2 WEEK 3 • An egg can live for two days. During that time, a girl is the most fertile. If the egg now comes into contact with sperm, it is fertilised. • After ovulation, the uterus gets ready to receive a fertilised egg. The uterus wall gets thicker, spongy and fills up with blood. This is the lining of the uterus. • An egg ripens in the ovary. • Each month, one egg is released. fallopian tube uterus vagina labia ovary cervix PREGNANT Implantation • If the egg has fused with the sperm, it implants itself in the lining of the uterus. The girl is then pregnant. • The fertilised egg cell is called an embryo. An embryo is how a pregnancy starts. This embryo grows into a baby. Pregnancy • A pregnancy lasts 40 weeks, counted from the first day of the last period. 30 LONG LIVE LOVE You can prevent pregnancy by: • Not letting the sperm get through: with a condom • Not letting the egg ripen: with the pill or another contraceptive • Not letting the lining of the uterus get ready to receive the egg: with the pill or another contraceptive
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