There are many factors that go into the discussion and opinions surrounding the topic of abortion. Let me give you a few perspectives.
Recently there have been many prominent African-American clergy that have equated abortions with race relations. They reason that most of the abortions are among low income and minorities. For this reason, they see racial overtones in the idea of abortion. There might even be the idea of population control.
When we add economic considerations, things get even more complex, because often times abortions are conducted, because of financial reasons. As you probably know raising children is an expensive endeavor.
Perhaps the most interesting element in our recent debate is the environment. Some people do not want to bring children into some places of the world due to pollution.
Most of these factors could be seen as reasons to allow abortions.
The basic idea would be that allowing and even promoting abortions in unwanted pregnancies would reduce the rate of population growth in the world. This would lead to less pollution as fewer people used fewer resources. It would reduce poverty as families close to poverty would not be burdened by more children than they could really afford.
On the other side, there is the issue of racial overtones. Since so many poor people are non-white, promoting abortion could be seen as an attempt at reducing their population and even as genocide.
Overall, though, this seems like a bad way to look at the issue of abortion. Abortion is, first and foremost, about the issue of when a fetus is alive. If a fetus is a human life, poverty and pollution would not be sufficient reason to allow abortions.