Birth Control Effectiveness

[natcmau]

Even though I believe in always using two forms of birth control (ie. condoms + the pill, condoms + withdrawal, etc.), I was curious how long it takes for the pill to be as effective as possible on its own. I know there are a lot of different factors, but let's say it's a combination pill and I started about halfway through my cycle. What would be the waiting period before the full effects of such a medication start to kick in?

[Heather]

When someone does not start a combined hormonal method like the pill at the same time a period starts, or on or before the first Sunday afterwards, it may take as long as one full cycle of pills for it to be effective, which is why one month of backup is suggested for those starting the pill at other times than those.