Do children sense pregnancy ?

So I'm 3 +6 weeks and have a 9 month old little girl , it's almost like since I found out I was pregnant she has be super clingy , won't let me put her down , even to the point I popped my head out the car window to talk to someone and my Lordy she lost it !! Haha could all be a coincidence but it's almost like she knows something is happening !! Bless her little heart