Contraception and sexually transmitted infections

Abstract

The link between different methods of contraception and the risk of acquiring sexually transmitted infections (STIs) raises several questions. Do the risks differ according to type of STI? Which methods reduce the risk of acquiring STIs and which, if any, increase the risk? How should people use such information when choosing a method of contraception? These questions have major public health implications because STIs cause a huge disease burden in women and are a major factor in driving the HIV pandemic. Some answers to these questions are fairly clear. The risk of STI acquisition is strongly related to the type of organism. The efficacy of transmission is higher for gonorrhoea and syphilis than for chlamydia or HIV. Other viral STI, such as human papilloma virus (HPV) are easily transmitted through genital contact. Barrier methods substantially reduce the risk of acquiring HIV/STI. The best evidence for this comes from studies of condom use and HIV prevention. Other questions are harder to answer. The particular concern raised by animal studies – that hormonal contraception might increase the risk of acquiring HIV – has not been confirmed in women. The methodological challenges facing further studies would be formidable. Since hormonal contraception is widely used, safe and highly effective in preventing unintended pregnancy, current approaches to promoting hormonal contraception should continue. The importance and effectiveness of consistent condom use to prevent HIV/STI should be stressed whether or not other contraceptive methods are being used. Future contraceptive research should focus on the dual goal of protection against STI/HIV and unintended pregnancy.