What's the science? Who qualifies as a person? We don't have a legal definition of that yet.
I'd be cautious about federal regulation. Do you like the new Homeland Security Disinformation Bureau?
I find the detectable level of brain function is pretty convincing. Personally, I'd restrict it to 12-15 weeks on the Federal level, and let the States decide within that time frame.
In Sweden, they use medically detectable brain function, and the "abortion on demand" limit is 18 weeks, with no abortions allowed after that, unless medically verified, unforeseen circumstances are proven in court.
In the U.S., the vast majority of both deliberate abortions and natural abortions ("miscarriages") occur in the first 12 weeks of pregnancy.
I didn't like "Homeland Security" to begin with. Just the name sounds Orwellian!