I saw Full Sequence. I'll be honest and say I found it perhaps less impactful than the first. The premise of the first was absurd and to see it in on film left some memories. The second is certainly more violent and vile, but I felt detached from it. I think the lack of ANY dialogue by the protagonist and the majority of "dialogue" from everyone else being simply screams and moans made it difficult to empathize with them.
Possibly another problem with this is that it was so damn violent, with so many people being clobbered by a crowbar in the head and/or killed that there was as close to no suspense as I've ever seen in a horror movie.
I've heard of that movie Serbia and I don't want to see it because it will possibly feel too real and thus be traumatic, but Human Centipede 2 was just so ridiculous and packed with nasty naughtiness that it was easy to see as fiction.
BTW, the "baby scene" at least what I saw was simply this: *SPOILER*: the pregnant woman escapes the warehouse near the end of the movie and gets into a car. As she's trying to start the car she is in labor and births her baby into the wheel well of the car while Martin is trying to get into the car. He is unsuccessful and she manages to get it started and drive off with her baby, thereby being the only victim of the lot to escape. Here -
http://en.wikipedia.org/wiki/The_Human_Centipede_2_(Full_Sequence) - it talks of the baby being killed. I did not see that. And the "sand paper" scene was simply removal of sandpaper and reaching into pants; there is no nudity during the scene.
I'm starting to think the US version has been toned down perhaps...