Women who have unprotected sexual intercourse or experience contraceptive failure can seek emergency contraception to reduce their chance of unintended pregnancy. Emergency contraception is a safe medication, and to be effective, must be taken within five days of unprotected intercourse. Several barriers can discourage use of emergency contraception, including an inability to obtain the medication fast enough. One proposed solution is to let women have a set of the tablets that they can keep for immediate use should it be needed.

"Providing emergency contraception before it is needed in case unprotected intercourse occurs gives women rapid access to the medication," says lead author Chelsea Polis, a PhD student at the Johns Hopkins Bloomberg School of Public Health, in Baltimore, USA.

Polis headed up a team of Cochrane Researchers who set out to see whether this sort of advance provision of emergency contraception influenced pregnancy rates, occurrence of sexually transmitted diseases, sexual behaviour and the use of other contraceptives.

They identified eight randomised controlled trials that met their inclusion criteria, which involved a total of 6,389 people living in the USA, China and India.

Despite increased use (single and multiple) and faster use of emergency contraception, advance provision did not reduce pregnancy rates on a population level.

At the same time advance provision was not accompanied by increased rates of sexually transmitted infections or increased frequency of unprotected intercourse. In addition it did not lead to women changing their use of other contraceptives.

"Women should have education about, and easy access to, emergency contraception because it can decrease the chance of pregnancy. However, the interventions for advance provision tested so far have not reduced overall pregnancy rates," says Polis.