Why do babies chin / bottom lip vibrate when they have dummy?

[flubdub]

My ds1 did this, and now ds2 (7 weeks does).
When he has a dummy, he sucks a couple of times, then his chin will wobble a little bit. Then he'll do it again.
Why?

i dont know about how muc it relates to the dummy, my boys have all done this, ds4 is twelve weeks and occasionally he will still do it, it almost looks as tho he is shivering or something? odd but like i said all of mine have done it when little

is that what they do when breastfeeding to stimulate the milk flow (thats what I always put it down to but could be talking out my arse )

I've never noticed my ds doing that.
Maybe they get a mimi cramp or something from all that sucking, I would. Keep it clean ladies!

All mine did that when breastfeeding though no idea why?

Immature nervous system

I did wonder if it was to do with bf too. I presume that it wouldnt work though?

My six week old is doing this. It looks awful; like he's cold, but I think I recall my DD doing it as well.

It's for bfing. Called a 'flutter' and it helps to stimulate the milk without having to suck, suck, suck all the time.

I don't know about dummies, but my babies did this when breastfeeding- I think it encourages let down but that's just my theory!

Aah, fondant, I'm not as daft as I appear to myself!

its to do with bfing as already said

dd (3 yo) does it while feeding

My dd (18 months) does it when she sleeps. It's so sweet..