Noted researcher Dr. Michael New just released new data refuting claims from pro-life Obama supporters about how to most effectively reduce abortions.  His article outlines the evidence.  A key excerpt:

During this election cycle, a study on abortion released by Catholics in Alliance for the Common Good (CACG) has received plenty of attention from Democrats and pro-life supporters of Barack Obama. The spin is that state level pro-life laws only have a marginal impact on abortion rates and increasing welfare expenditures is a superior strategy for reducing the incidence of abortion. However, the study contains methodological shortcomings. A proper analysis of the data demonstrates that pro-life laws are effective — and casts serious doubts about whether more generous welfare benefits actually result in abortion reductions. Furthermore, a closer look at the results actually provides evidence that some pro-life laws are effective.

Update:  Here's a link to the more extensive version of Dr. New's research.