I've always wondered that too..
Most women forget to focus on holding in their Transverse abdominal muscles while they are pregnant and truly forget how to tone these muscles after birth. Its simply correcting your Posture and sucking in your tummy that helps correct this issue.
My 2nd pregnancy, I was far more aware of my posture and I kept my Tummy tight. I drank Red Raspberry Leaf tea which helped shrink my uterus also.
Now that I'm pregnant with my 3rd Baby 2 1/2 years later, I still maintain my posture and keep my Tummy sucked in.
Your belly doesn't have to get Bigger faster, as long as you maintain good posture and train your Transverse abdominal muscles to be stronger.
This is not an Abdominal workout. Just simply breathing ♥
Because in your first pregnnacy it destroys your abs ect and it does again every other time but obviously isn't as difficult to get through once it's happened before xx
Maybe because their belly has already stretched out once so maybe it stretches out faster the next pregnancy lol idk I'm not really sure why.. I'm a ftm, but that's my guess haha!