WHen my mother was in labour, the doctor used something to break her waters. I came out with a little cut on my forehead and on the back of my head. I still have the faint scars today. I have no idea what he used (it was the 70s) or how he managed to make two cuts, but he told my mum not to worry they'd go away.
In a similar vein, I have a flat 'gouge mark' scar on my cheek, under my eye from the forceps when I was delivered. It's only noticeable in certain light, but it was definitely there when I was a baby!