How Does Contraceptive Pills Control Pregnancy? The combined oral contraceptive pill is often just called "the pill". It contains artificial versions of female hormones oestrogen and progesterone, which are produced naturally in the ovaries. If sperm reaches an egg (ovum), pregnancy can happen. Contraception tries to stop this happening usually by keeping the egg and sperm apart or by stopping the release of an egg (ovulation). Dear Readers, did you know this?