Although you ask a good question, it would seem to me you miss more than half the argument.  First, abortion abroad are directly funded  by US tax dollars when the Mexico City policy is removed, which Obama did.  Thus, if we care about all lives, not just abortions in America, this is a key part of the equation.  Second,  the abortion rate in the US is less amenable to a single cause explanation.  Much of the reduction  is in states controlled by Republicans in which restrictions have been introduced despite federal support.  Additionally, some of the reduction in the official rate is clearly attributable to the increased prevalence of abortifacients encouraged by the Obama administration's policies.    I am unaware of a an argument in Catholic teaching that such early abortions are somehow acceptable.  Thus, yes, I want to reduce abortions, but would like to do so worldwide, and have serious doubts about the reliability and causes of the alleged drop under Obama.