Carton containing three blister packs of combined contraceptive pills 'Ovysmen 0.5/35', monophasic, one of 2, with instruction leaflets, by Ortho-Cilag Pharmaceutical Limited. Saunderton, Buckinghamshire, England, 1982

Monophasic pills such as ‘Ovysmen’ are taken for 21 days with a week in between packets. The pill suppresses ovulation, which is the release of eggs into the womb. They also make it difficult for sperm to reach an egg, or for an egg to implant itself in the lining of the womb. Each pill contains the same amount of oestrogen. Oral contraceptive pills prevent pregnancy. However, extra precautions are needed to prevent sexually transmitted infections. The pills are shown with other oral contraceptives.