Nobody is preventing anyone by force. Women should just ask their doctors the question.
But there are a lot of nut jobs (as we have seen) who want to kill doctors who perform legal abortions. I don't know why anyone would want that info published.
Actually, there are not a lot of nut jobs who want to kill abortionists. There have been 25 attempts since 1991(see http://www.religioustolerance.org/abo_viol.htm). Since James Kopp was responsible for probably 5 of these attempts, and Eric Rudolph for at least two of them, that means that less than one person per year has tried to kill an abortionist in the past 15 years.
By way of contrast, there are about 2,000 abortionists in the United States. (http://www.findarticles.com/p/articles/mi_qa3634/is_199811/ai_n8815506 ).
Thus the nut jobs who kill babies outnumber the nut jobs who kill abortionists, by 2,000 to 1.