Women seeking protection from pregnancy require adequate information about
the relative merits and risks of current contraceptive options in order to
make an informed choice. A basic understanding of mechanisms of action, the
projected rates of efficacy, the demands on compliance, and the risks of s
ide-effects permits women to weigh options appropriately and attain confide
nce in their chosen method. An informed woman is also in a better position
to switch to alternative methods in the event of dissatisfaction or changin
g needs. Within the category of highly effective methods of birth control,
to which a monthly combination injectable contraceptive has recently been a
dded in several countries, there are important distinctions in relative rev
ersibility, effect on menstrual cycle and confidentiality.