I must be missing something. I thought the current limit was the first trimester, which would be 12 weeks. Is there no limit currently?
Roe v. Wade effectively established a time limit to before viability, which at the time was basically limited to the first two trimesters. However, judicial interpretation of
Roe v. Wade has effectively removed that limit as states repeatedly try to further restrict abortion and the courts repeatedly strike them down. At the same time, viability has steadily moved up - I think I saw reference to a five month preemie (around 22 weeks!) surviving.
It needs to be said that the mother legitimately has rights even after fetal liability, so it's not an easy question, and anyone who says it is an easy question is lying or simply wrong. That abortionists routinely abuse those rights does not mean the rights themselves are illegitimate. That legal liability attaches to those terminating another's pregnancy against the mother's wishes also does not mean the mother's rights themselves are illegitimate.