How reliable is birth control pills?

My girlfriend has been on the pill for two months now. Should we worry about getting pregnant without using protection, or is the pill pretty reliable?

It's about 98% effective.

When taken correctly, the pill is 99% effective. That means that over the course of a year, someone taking the pill correctly has a 1% chance of getting pregnant.

Some things that can make the pill less effective:
Taking certain antibiotics
Not taking the pills regularly
Vomiting or diarrhea which cause the pill to not get digested
Taking a "low dose pill." I have heard of lots of people getting pregnant while using the pill, even taking it at the same time every night, and much of the time they were taking low dose formulations.

How effective clinically or in practice? In practice 14 out of 100 girls get pregnant on the pill. Effective is 95-98. It is more effective to use a condom as well, and that will also help protect against STI's. The effectiveness is of course affected by how routinely it is taken, but it is really hard to take a pill every single day at exactly the same time, or if she is on other medications it will effect how effective it is as well. It isn't seen as healthy too take them for too many years either as it can increase your risk for some cancers after about 5 years, so might as well use a condom now, you'll be more safe, both be responsible for being protected and then you won't be mad if you have to switch to condoms because you'll be used to it.

The pill is 98% effective, while a condom is 97% effective & when so many ppl get pregant today, it makes everyone wonder if these numbers decrease the more you sleep w/ one person. playing the odds, so to speak. in my opinion it might have something to do w/ the reason why men feel the urge to sleep around & not committ, bc their afraid of the added responsibiity that comes w/ being a father. your friends chance of not getting pregnant is better if while she's on the pill her boyfriend is also using a condom. "doubling-up" in terms of safety. she should also consult her doctor bc if your on the pill & u take an anti-biotic it makes the pill not work in most cases & so tell her to be careful not to mix certain meds.

I really wish you would have listed you and your girlfriend's ages and how long you have been in a relationship for. The pill is about 98% effective, but all it takes is missing ONE pill, for your girlfriend to get pregnant. If you are at a point in your relationship where a child would not be a sensible thing, you need to be extra cautious. My aunt got pregnant with 2 out of her 4 daughters on the pill. Does that tell you anything? This is my advice to you....wear a condom. Be extra safe.

birth control pills are effective for birth control. but, even though the chance is low, you may still get pregnant. using a condom and birth control pills at the same time may be the best. but dont forget about STDs and that without a condom, there is a higher risk of developing one.

The pills are effective by now and as long as she takes them daily when she's supposed to they're about 98% effective. Most failures from the pill come from women skipping them or not taking them regularly.

It is about 97% reliable, but still you should make sure to use two condoms just in case.

Not as reliable as closing your legs.
But reliable over all...

It is about 97/98%. Condoms are about the same too. Even with both together, there is still a chance she can get pregnant.