How effective is birth control?

[mrdancemoves]

my friend says 99.9 percent. i say no (the pill)

[jenny_pizzle]

when the pill is taken 100% correctly it is 99,9 percent effective,
but the average person does not take the pill 100% by the directions.
taking it every day at the same time is important for a reason
and if you take antibiotics and some other meds it changes to

[akalilbit08]

it depends on the type of birth control...depo provera and IUC's are very close to the 99% effectiveness rate. they have a greater effective rate when a condom is used.