In a paper on abortion, a student writes
The only way not to get pregnant is not to have sex. I feel she should not be allowed to have an abortion for the simple fact that nothing can stop pregnancy and the only thing to prevent it is to not have sex at all. If you do not want a baby you should not have sex, period.Abstinence may work 100% of the time, but vows of abstinence have a failure rate between 26% and 86%. Condoms, by comparison, fail 12% between and 70% of the time, almost always because they are used improperly. Used properly, condoms fail 0.5% and 7% of the time.
You say 'if you do not want a baby, you should not have sex,' but the situation isn't so simple. You cannot choose "no sex ever," as if you were selecting Safe Search on Google. You can pledge abstinence, but that will probably fail, at which point, it would be good to have a back up plan, such as using condoms and using them properly.
Even then, though, there is a chance you will still get pregnant. This brings us back to the issue of abortion. It is tempting to look at a pregnant woman considering abortion and think 'she is completely different than I am. I could never be in that position." But, in fact, she may have done all the things that you have done—taken a vow of abstinence, learned to use condoms correctly as a back up—and still wound up in that position. Like it or not, a lot of what separates you and her is just luck.