The Center for Reproductive Rights says a study it conducted found that abortion doctors and clinics in some states, including Missouri, "are routinely targeted" for both legal and physical harassment, the Kansas City (Mo.) Star reported Thursday.
Center President Nancy Northup says the number of physicians and clinics providing abortions have fallen by 25 percent since the 1990s.
The state of Missouri has only three clinics that offer abortions, Northup says.
Some states, such as Mississippi and North Dakoka, have only one abortion provider while Alabama has seven.
Texas has about 40 clinics and doctors performing abortions while Pennsylvania counts about a dozen.
The study undertaken by the New York-based Center for Reproductive Rights was concluded before the slaying in May of Dr. George Tiller, who ran a Kansas abortion clinic.