I'm not sure what you're asking. You're asking how effective the pill is? Assuming the woman is on the right dosage for her and she takes it religiously and at the same time every day, etc.. Best case scenario it's about 96-97% effective.
Considering most people forget or are on the wrong level for their hormones or don't take it correctly.. it's probably closer to high 80's effective.
Let's put it this way. My sister has 2 kids.. one from when she was on the pill and one while on the shot.
