Our daughter is 3 months and she started sucking her thumb. Is there anyway we can stop her from doing it so it doesn't go too far or is this a habbit
She's probably just doing it for comfort.
Only thing I could think of if you're wanting to prevent it is to put the little mittens on her.
My daughter had this phase. I think it was a comfort thing while teething! She used a pacifier anyways so I put socks over her hands. If I didn’t have socks on her I’d correct her. She did this for like 2 weeks