yeah only the thread burns!;)

Seriously though, some are heat resistant so you can iron over them.
Also many commercial childrens' items are sewn with monfilament thread. The only time I've had a problem was in a purchased sleeper.. A thread wrapped around the end of DD's toe. No permanent damage but after that I checked the insides of all the sleepers fo loose threads.

I really like it for top thread for SID. You can not see your mistakes. I use matching thread to backing on bobbin.

I only use the polyester invisable thread. I don't seem to notice the pokeys.

Mary

There are invisible threads that are not pokey...YLI comes to mind..it is a very soft thread, and I have ironed over it and it has not melted. I don't know if I would use it for a baby quilt, but I have used it a lot. It comes in clear and a smoke color...which sews out as a pale grey...depending on what colors you sew with, the clear is good for whites and clear colors, pastels, and then the smoke for just about anything else. The clear will look too shiny on darker colors

I ocassionally use the YLI and it is very soft and nice. If I'm using a invisible thread this is the brand I prefer. Regular cotton thread can wrap around a babies toe or finger and cut off circulation also. It actually happened to my oldest dd and it took us a while to figure out why she was in pain. She was okay after we unravled the thread.

Yes any thread can cause a problem.
i have used invisable thread for quilts without problem. i do make sure I trim threads right away otherwise they are hard to see (at least for me)