Oral contraceptives, colloquially known as "the Pill". The most common form of pharmaceutical contraception, a pill for women taken daily containing doses of synthetic hormones (oestrogen and progestogen) with doses adjusted in synchrony with the menstrual cycle. It is used by millions of women around the world - as an indication, approximately one-third of sexually active women in the United Kingdom use it for contraception, though this varies considerably by region - in Japan what amounts to a boycott by doctors making huge profits from abortion has led to the pill being banned for nearly 40 years, and its recent introduction has seen very few women take it up.
The Pill works by preventing ovulation, as well as making the uterus less likely to accept implantation of an embryo if one is created, and thickens the mucus in the cervix making it more difficult for sperm to reach any egg. It is one of the most reliable forms of contraception, with less than one in 100 women using the pill becoming pregnant in a year of continuous use.