I'm sometimes asked, "What is the Buddhist position on abortion?"  I'm also occasionally asked about the Buddhist position on suicide, homosexuality, and other cultural war issues.

They're trick questions.  There is no "Buddhist" position on anything, as there is no central Buddhist authority and no single Buddhist text or doctrine from which all positions and attitudes are derived. Any Buddhist telling you the "Buddhist position" on anything is just telling you his or her personal opinion.

But a couple comments on the abortion issue.  In almost all schools of Buddhism, there is a precept against killing, and different schools address the precept differently.  All would agree that murder is a crime, but some schools practice strict pacifism while others might acknowledge the theoretical possibility of "just war" (e.g., defending the innocent, stopping tyrants from killing others, etc.).  If a Buddhist were to consider abortion to be "killing," then they might be against the practice as a violation of the precept.  After that, there's the matter of refraining as a matter of personal choice versus forbidding anyone else from the practice.

On the other hand, many anti-abortion zealots feel that at the moment of conception, a new life is created and that the new life instantly has a self independent of the parents.  In most schools of Buddhism, there is no "self" and there is no "soul" independent of others.  A zygote consisting of nothing more that a cluster of cells may be living, but is no more a "self" than any of the other living organs or tissues of the parent, and it is not a potential or future "self" as there is no separate existence apart from all the rest of the universe.  In this view, removing a zygote or a developing fetus from a uterus is no more "killing" than removing an appendix from a large intestine.

Each individual Buddhist determines where their own feelings regarding this matter lie on the spectrum between these two endpoints, and what responsibility, if any, they have to impose their feelings on others.  Many Buddhists are strict vegetarians or vegans, but very, very few insist that all consumption of meat stop immediately.  Also, some Buddhists recognize that even if they were personally opposed to it, if abortion were made illegal, the practice would still continue but under less safe circumstances and more women would die from the procedure, and that the more compassionate act, the more humane approach, might be to keep it legal as a relatively safe medical practice. 

No, there is no official Buddhist position on abortion, and the "pro-life" versus "choice" controversy seems to be unique to the Christian faith.