This information is from the fda website so it should be pretty accurate:
http://www.Fda.Gov/fdac/features/1997/baby tabl.Html

oral contraceptives--combined pill
fda approval date: first in 1960; most recent in 2003
description: a pill that suppresses ovulation by the combined actions of the hormones estrogen and progestin. A chewable form was approved in november 2003.
Failure rate (number of pregnancies expected per 100 women per year): 1-2

(this information is if you are taking a combined pill with both etrogen and pregestron, such as yasmin. It is the most common type of pill so you most likely use this type.)

oral contraceptives--progestin-only minipill
fda approval date: 1973
description: a pill containing only the hormone progestin that reduces and thickens cervical mucus to prevent the sperm from reaching the egg.
Failure rate (number of pregnancies expected per 100 women per year): 2



i hope you found this information useful. Don't worry about being pregnant, if you are use the pill correctly there is less than a one percent change you are pregnant.

Take your pill on time.
If you have an upset stomach -- vomiting or diarhhea -- use another method (condoms, or non-penetrative sex) until your next period.

If you do these two things, you are removing about 80% of the reasons why pills fail.

Don't be paranoid. If you are going to use hormonal birth control, you might as well get the benefit from it!

I have missed my period and i am on birth control i have had some spotting but it has been 5 day's and i am usually have a heavy period i did not miss any pill's i am on allergy pills but i would not think that would cause a problem with my birth control i have two kids and i know all the signs and i fell like it but i took a pregnancy test and it came out negative i think that i might just be freaking myself out but why else would i skip my period?

Also check any medications you take to make sure they don't interfere. That includes prescription and herbal. Then you'll remove the other 19% of why they fail!!

*I don't think allergy pills should interfere but you should ALWAYS check with your doctor or pharmacist before you take anything. Certain steroids, antibitics, etc. can effect it.

Your missed period is most likely due to something else.

I'v been taking the same birth control for almost 2 years now, I let my husband cum inside me and I don't take it at the same time. Sometimes I even miss taking one or two pills, but I have yet to get pregnant. I sometimes miss my period even on the week that I'm supposed to have it, I get all the symtoms a pregnant woman would have, but I'm not pregnant. I think birth control works different for other woman.

I really need help!
I've been on birth control but half way through the pack i've started to bleed....i had unprotected sex twice and he cummed in me both times...because i'm bleeding and everything does this mean i have a chance of now getting pregnant?
Please reply asap coz am propa wuried about it.
Fanx

When taken correctly, birth control pills are more than 99% effective. Correctly, however, means always taking your pills in your time slot (3 hours for the progestin-only, 12 for combined pill), and not experiencing anything that would make the pill less effective.

People whose failure rates are higher are called "typical" pill users, whereas those who use their pill perfectly are called "perfect" pill users. Typical use refers to women who sometimes miss pills, take them late, are taking contradicting medications, or experience vomiting/diarrhea which may make the pill less effective. Typical users usually experience a 4%-8% chance of becoming pregnant if they are not using their pills perfectly.

As long as you take a pill every day and do not experience any of the circumstances above, it is highly, highly unlikely you will become pregnant.