Unfortunately, this is a bad argument.
‘Baby’ is not a technical term, and people will generally call newborns, infants, and toddlers ‘babies.’ I wouldn’t really call the fetus out of the question as another subcategory. People would not be called strange to say that it was a baby in there at 38 weeks pregnancy. But that’s a fetus.
A newborn would be ‘full term’ at 38 weeks if it needed out; not even a premie. Yet a newborn is undeniably a ‘baby.’ So why is it not a baby still in uterus?
I’m not arguing in favor of them, mind you. That argument is too annoying for me to want to touch anymore than I did here. Just, you aren’t exactly right either.
The general use isn’t relevant in the context of the law. Ketchup can be a vegetable if the law says it is, but this law, which may or may not even exist, was likely passed before Alabama law turned fetuses into “people,” and as such is likely not as extreme.
It would be very hard to argue that a law intended to make sure a baby/toddler/child was safely out of the driver seat would apply to a fetus. A fetus cannot be strapped into a car seat or seatbelt, as it can not exist outside of a woman and be a live fetus. If the fetus is viable, then it would become a baby at that point, and the law would apply, but then the argument the woman is making would not.
Pragmatically and literally, i can’t see a way for this safety law to apply to a fetus, so I don’t expect a judge would find the argument novel or noteworthy either.