Each person has a unique reason to be pro-choice. Here are some of ours.

I am pro-choice because I don't think there is any reason why a woman should have to face all the consequences from something she did not do alone. If a guy can get a woman pregnant and then run away, there is no reason why she should be the one responsible for everything. Having more options puts a woman on more equal footing with men, instead of being someone of whom they can take advantage. In addition, I believe that it is best for a child to not be born at all than to be born hated, to a mother who is forced to have him because she has no choice, and not because she wants the child.
Undergraduate Student in Chemistry

The single most important factor for women's advancement in society is our ability to control our fertility. Without that, we are trapped by the realities of pregnancy, childbirth and childrearing; rather than a privilege and a gift, these aspects of being female become an unbearable burden. Attempts to limit women's reproductive freedom are no more than a gambit to keep women "in their place"-- a gambit in the guise of religious moralism. True, the guise can run deep, and many so-called "pro-lifers" genuinely believe that killing a fetus is equivalent to killing a human being. But such religious feeling has no place in the public policies of a country that claims to separate church and state. In the words of supreme court justices O'Connor, Kennedy and Souter: "At the heart of liberty is the right to define one's own concept of existence, of meaning, of the universe, and of the mystery of human life." No one wants to plan an abortion. But the best way to prevent abortions is to prevent unwanted pregnancies: through sex education, improved distribution of birth control, and general empowerment of women to shape our own individual lives.
Graduate Student in Biology

I think one of the biggest problems with the abortion debate is that the two sides aren't in direct opposition. The pro-life movement seeks to force their moral beliefs on others - grounded in their own religion or personal philosophy. The pro-choice movement doesn't make claims on the morality of abortion - we leave that as an individual choice for every woman faced with an unwanted pregnancy. If they feel abortion is wrong and they want to give their child up for adoption, or keep it, we will support their decision. Pro-life people say "Abortion is wrong;" we only say "Abortion is." Making abortion illegal won't stop abortions from happening, it will only stop them from being safe. 43% of abortions worldwide are illegal. Changing laws doesn't solve the problem, making contraception available and affordable does. If we are to maintain the separation of church and state so central to our nation's identity, we cannot have some people forcing their beliefs on us all.
Undergraduate Student in Linguistics and Philosophy

I believe strongly in taking responsibilities for one's actions. I believe that people should practice safe sex or abstinence. And I believe that the consequences of an unwanted pregnancy can be worse than the "benefits" of having irresponsible sex. However, in some cases, I believe that abortion IS taking responsibility. Bringing an unwanted child into the world is irresponsible. I am not pro-abortion. I am pro-choice. I believe that every woman should decide what to do with her own body without restrictions placed on her by a strongly religious government that ironically preaches the 200 year old doctrine of the separation of church and state. On that note, I think religious freedom and education are also a constitutional right of every citizen, but they do not belong in the hospital room. Reproductive freedom is just as sacred and constitutional as religious freedom. And I am not the opposite of "pro-life." I love life and I love babies, but an unwanted life can be worse than no life at all. I think safe sex and abstinence education is needed. Like many pro-choice believers, I want the number of abortions to be limited, or at least I want to limit the overwhelming need for abortions.
Graduate Student in Materials Science and Engineering

I'm pro-choice because it's the only option that isn't poisoned with misogyny. I believe that we are responsible for justifying our beliefs, and just as one cannot claim that a given race is inferior to another because "it's what I believe", I don't think one can argue that old white men can assert control over a woman's uterus -- and future -- because they claim to believe that a fetus is comparable to a human life. That belief is so clearly a result of the fact that only women can get pregnant and only women would ever have to carry an unwanted fetus to term that I find it laughable that anyone claims being anti-choice has anything to do with concern for potential life. Can anyone really believe that abortion would even be an issue if men had to face the possibility of giving birth to and raising a child because of one night of failed contraception?
I think Florynce Kennedy said it best: "If men could get pregnant, abortion would be a sacrament."
Undergraduate Student in Mathematics