Why is my 3 year old being like this now ?

Currently 31 weeks and lately he’s been super cranky/clingy and acting like a little baby ! He was never like this before , but now that I’m getting towards the end of my pregnancy he’s been such a emotional wreck always wanting to be held or sitting directly on my lap, can’t leave the room without him following me or crying, crying over the littlest things 😔Getting super overwhelmed dealing with all this ! Has anybody else experienced a change in their toddlers during pregnancy??