I figured I'd answer your other question, since the safety question has been thoroughly answered.

Why am I choosing to birth unassisted?
Like others, I don't believe that pregnancy and birth are medical conditions, and when you have healthy mothers/babies and no complications, UC can easily be accomplished.
But one big thing for me is privacy. When I am in pain or discomfort of any kind, I need to be in my own little world to deal with it. As a child, whenever I got hurt, I would yell at my mother (who would run over and try to comfort me), "Don't touch me, don't touch me!" I do not deal well with pain (not saying labor/birth is always painful no matter what, but you know what I mean when I say pain) when there are others there trying to touch me, or even talk to me. Being around people (even family members) when I am in discomfort just stresses me out and annoys me.
I also believe that a lot of interventions they do in hospitals are completely unnecessary, and are usually for the convenience of the doctor, not the benefit of the mother and baby.
One more thing, I just think the hospital setting is so...UGH. It's so impersonal and ugly and gross. I just do not think of it as a good place to give birth.
All of this being said, I do still think of the safety of UC. Because I don't believe I will find a midwife that will assist me with the birth of my twins, or one that will be covered by Medicaid, or one that will be hands-off, I have not searched for a midwife.
I did, however, go to the hospital and was assigned a random OB (I'm not really picky, and he's not a jerk or anything, just pretty straightforward) to do my prenatal care. I have been thankful for this care, because if I hadn't gotten it, I may not know I was carrying twins, and I'd worry about my health and the health and presentation of the baby (in this case, babies). So getting prenatal care has been good for my peace of mind, and it has been a deciding factor on whether or not I would definitely birth unassisted or not.
So far:
- I am completely healthy and have no complications. I will be going on leave in less than two weeks (I will be 32 weeks then) to avoid complications...I'm measuring full term and have 7 pounds of baby in me already.

- Both twins are healthy and so far have no complications. No TTTS, one isn't growing at the expense of the other, and both are head down and have been since before I was 24 weeks.
These are two huge deciding factors for me. Another is the fact that I can get to the hospital in five minutes, no exaggeration. If I lived farther from a hospital, I'd at least want to give birth closer to a hospital. If I just lived too far away, I'd probably have a hospital birth.
So for ME, so far so good. But UC isn't for everyone.