Toddler Has Developed Thumbsucking Habit After New Baby Arrived

I'm not sure what to advise as we weren't able to get ours to stop. We used that bitter polish and it didn't work. It doesn't even last long. Like maybe a few minutes before it's sucked off. I later read that it's not a good idea to use that stuff or try to stop them. I wish we'd known that before we put mitts on her. She became so stressed by the deterrents that she developed trichotillomania and snatched her hair almost bald on the right side in just a matter of a few days. After that we left her thumb(s) alone and she stopped pulling out her hair. Fortunately, her hair is growing back quite nicely and she seems to be weaning herself from her thumb. I think she's using it less because she is using her hands more for activities. Maybe you can give your little girl something to keep her hands busy.

The more you pay attention to it the more she will do it. I would try painting her nails with something and not even tell her what it will taste like.

Pretend she isn't doing something wrong. The more you focus on it the more attention she gets for doing it. I would totally ignore it and just work behind the scenes to make it unpleasant or unrewarding for her to do it.

I didn't, but had a brother who did. Mom ignored it and he did it into his teens, so I agree, I would want her to stop.

Doctors now know that thumbsucking can cause problems in little ones as young as 2. It puts pressure on the sides of the upper jaw and soft tissue on the roof of a child's mouth. The upper jaw can narrow, causing the teeth to not meet properly from the top to the bottom. This can be fixed later with braces, but can also cause speech problems, like a lisp that may need to be corrected in therapy. And more.

Speech development, using their vocabulary, seems to help them not need to suck, so I would work on that with her, as well as reinforcing your love for her as your first child and her role as a big sister, pour it on.

These aren't specifically about a 2 year old starting to suck her thumb after a new sibling, but do offer why little ones do it and ways to curb it:
http://www.parenting.com/article/ask-dr-sears-stop-thumb-...
http://www.webmd.com/parenting/guide/9-ways-to-wean-a-chi...

I'd just completely ignore it. You KNOW that she's doing it for attention since she's laughing and putting her thumb right back, you don't know that she will start to like it and it will be a habit. I'd bet she forgets she's doing it once she stops getting any attention for it. Congrats on the new baby!