Combined contraceptive pills
Combined contraceptive pills (usually simply called the pill, also called combined birth control pills) are pills that stop a woman from getting pregnant. They contain two different sex hormones, oestrogen and progestogen. The main way they work is by stopping the egg cells in the ovaries from maturing. This means there is no ovulation. Because of this, the woman can’t get pregnant even if sperm cells enter the womb or the Fallopian tubes.
As well as stopping ovulation, contraceptive pills make the mucus in the cervix more sticky, making it more difficult for the sperm cells to enter the womb.
The third effect these pills have is that they affect the mucous membrane in the womb, making it more difficult for an egg cell to attach itself to the lining of the womb if it does get fertilised. So there is a slight possibility that these pills might stop a fertilised egg from attaching itself, and because of this some people choose not to use these pills.
If these pills are taken regularly every day, they will stop ovulation so that there can be no fertilisation. However, if you forget to take one, you should also use another type of contraception, such as a condom. Then there will be less chance of getting pregnant, and if ovulation has occurred the condom will stop the egg cell from being fertilised and then rejected after fertilisation.