Anynody else knlw why our stomach sticks out ?

After a yesr or so gettinf bCk to working out after mg first child. I noticed mg stomach muscled would buldge out everytime i do a sit up or crunch... ?? Anyone know what the cause is ? Im on my 2nd child now and i know it wong go away now . but hopefully after him it will...

This is on a slight crucnh when i lay down. When i lay down it goes flat.

Flat with a slight belly cos im 26 weeks lol

Buldge...