Does the evidence support global promotion of the calendar-based Standard Days Method (R) of contraception?

摘要

Objectives: To scrutinise claims about the effectiveness of the Standard Days Method (SDM). The SDM is a calendar method with similarities to the rhythm method that has now been reclassified and is marketed as a modern contraceptive method. As promoted, it requires users to avoid unprotected intercourse on days 8-19 of the menstrual cycle. It is used in at least 100 countries. SDM has been researched, developed, and is marketed by the Institute of Reproductive Health (IRH) at Georgetown University, USA, and a for-profit company Cycle Technologies. SDM proponents say it is a major advance on traditional periodic abstinence, claiming that it is 95% effective when used correctly - rivalling pills and condoms. The effectiveness claim is repeated in recent documents from the World Health Organization.