Condom Failure rates

LegacyUser

Im a little confused by condom failure rates. I've read 2% for perfect use and some places say if you have sex 100 times then 2 times will result in pregnancy. Then I've also read, over a year, if 100 couple have sex (which could be 1000's of times) it will result in 2 pregnancies. Can someone clarify this? Thanks

Talliesin

Contraceptive effectiveness is measured by the per-annum pregnancy rate. If a contraceptive method has a per-annum pregnancy rate of n% this means that for every 100 women using it n women will get pregnant in the course of a year.

This is a rather difficult thing to get good statistics on (since they have to be adjusted to cover the under-reportage of abortions [both induced and spontaneous - that is to say what are called "mis-carriages" in everyday speech but "spontaneous abortions" in terms of medical science] and the fact that people will often change contraceptive methods during the course of a year) and as such even the figures on deliberately not using contraception is hard to place.

For the sake of comparison the US figures for using no contraception is recorded as a 89% per-annum pregnancy rate but this is reduced to 85% in the published statistics to represent the effect on these figures of a switch to using no contraception from using some form of contraception over the course of one year.

There are different methods used to calculate the rates - the Pearl Index and Decrement Table. Don't ask me what the difference between these two indices is though; I've studied safer-sex techniques, not statistical techniques!

You are correct that a couple having sex 1000 times a year would obviously have a different risk to a couple who only had sex twice over the course of a year (though a few hundred of those times would have been during a period of infertility). The fact that surveys are normally done for the first year of usage means that it tends to be couples who are definitely sexually active and contain few in the survey how aren't actually having sex. One of the difference between the Pearl Index and the Decrement Table is how they approach this to attempt to give a good indicator of effectiveness.

Statistics for typical use are even more difficult, since the difference between typical use and perfect use is going to differ depending on how well-informed the user population is, which in turn will vary drastically from community to community and country to country. Natural fertility rates also vary. It's worth noting also that the typical use rates in the US is 15% which is considerably higher than the 2% of perfect use. This underlines the importance of reading the label (and read it again if you're using a different type, e.g. those without a "teat" are put on differently to those with one) and educating yourself as to correct use.

milod

I used condoms with my ex for 10 years and only ever had ONE fail (I put it on while drunk and it burst...). It was our most effective option as for various health reasons the other options weren't a runner.

The one advantage with condoms is that you can establish after the fun is done whether or not they've failed and you have time to arrange an alternative, e.g. the morning after pill.

It's also possible to misuse condoms such that you end up pregnant, but that isn't condom failure, it's human failure, e.g., failing to remove the condom while still erect, or using a lube like vaseline that degrades the condom. If you read the instructions and follow them, there should not be a problem. Real life failure rates quoted at 15% are generally due to stupidity or drunkeness. But if you're capable of actually reaching a climax, you're probably sober enough to see whether the rubber is intact afterwards!

Talliesin

milod wrote:

The one advantage with condoms is that you can establish after the fun is done whether or not they've failed and you have time to arrange an alternative, e.g. the morning after pill.

Note that this is not an absolute test. Semen residue will be found in a very small percentage of women following sex with a man who correctly used a condom without observable failure.

The results of that risk is included in the 2% per-annum pregnancy rate quoted.

The good news is that when there is observable failure there may have still been some protection (about 50% chance you were protected in the case of a tear and about 80% chance you were protected if it slipped). Of course the protection rate in such cases is so poor that it could still be advisable to use emergency contraception after observing such a failure, but it's good to know that your odds are still better than if you had had completely unprotected sex.

watna

Would be an option for you to use two methods of contraception?

I find this to be the most reassuring thing to do. Having a pregnancy scare and constantly worrying about it can take the enjoyment out of sex. By being extra careful you are not only reducing the risks but reducing your worry as well. You just have to be careful to find the methods that suit you both best.