well, this may be a bit weak in the logic area, but with the knowledge that some of the first trimester abortions could be transformed into non abortions, and that more conceptus could be implanted, if these remedies were not instituted world wide it would be sin of ommision, not unlike a sin of commision with 6 week abortions. Once you have the knowledge, but do not apply it freely and uniformly to the whole population, you are letting the non medicine receiving patients abort more often "spontaneously".
In this way withholding medicine could be considered as the same logically as causing an abortion with an operation or a pill.
Similarly, hypertension and diabetes lead to later term abortions. Proper medical care decreases later term spontaneous abortions. Is the lack of medical care in say Moldavia which causes a higher spontaneous abortion rate the same therefore as "active " abortion?