Lame duck Republicans want a law to define that a fetus can feel pain at 20 weeks. Scientists have accepted that a fetus can feel pain at 28 weeks (7 months), but have not come to a consensus about 20 weeks - the fetus does withdraw from stimuli, but it could be a reflex due to any stimuli, or a pain response, it's not clear.
Folks, passing a law doesn't make anything more true. You can't "legalize" that pain starts at 28 weeks if it turns out that it doesn't. You can't make the sky pink by passing a law. You can't make π equal to 3. It just doesn't work that way, these are fundamental properties of the universe, and the universe doesn't give a shit about the laws humans make up. Someone should send these idiots back to grammar school.