The crux of the Roe argument was that abortion is possible up until the fetus is viable. It was assumed that second trimester abortions were legal since the technology of the time could not save a more premature fetus. Given that logic, only early second trimester abortions would be legal today.

And what of the progress of medical science. If we can save a 14 week fetus, shall we ban second trimester abortions?