Yeah... I'm still not sure what to make of this. It seems to me that they've changed the definition of fetus in that state to give it full personhood, but after reading the amendments to the bill, it SEEMS like it's saying that they aren't going after currently pregnant mothers or their doctors who are performing legitimate medical procedures.... so maybe it's to target someone who, say, attacks a woman and then causes the death of the fetus?

I'm not good at all, at reading 'legalese'. Anyway, the (very short read) PDF link is here:
http://www.capitol.tn.gov/Bills/107/Amend/SA1229.pdfIn case PDF links don't work for you, here's the relevant bit:
SECTION 1. Tennessee Code Annotated, Section 39-13-214, is amended by deleting subsection (a) in its entirety and substituting in its place the following: (a) For the purposes of this part, "another" and "another person" include a human embryo or fetus at any stage of gestation in utero, when any such term refers to the victim of any act made criminal by this part.
SECTION 2. Tennessee Code Annotated, Section 39-13-214, is amended by deleting subsection (c) in its entirety and substituting in its place the following: (c) Nothing in subsection (a) shall apply to any act or omission by a pregnant woman with respect to an embryo or fetus with which she is pregnant, or to any lawful medical or surgical procedure to which a pregnant woman consents, performed by a health care professional who is licensed to perform such procedure.
Sections 3 and 4 are the same as 1 and 2, just modifying different old subsections of the bill.
So, SEEMS like they're using the terms "another" or "another person" to refer to embryos or fetuses at ANY stage of the pregnancy, but it also seems like they're saying that their new definition doesn't apply to any act a pregnant woman does, or to any lawful medical/surgical procedure. Hmm. If anyone reads anything differently into it, let me know, please.