It's not muscle memory lol.. it's that after ur 1st ur stomach muscles are not as tight as a 1st timer so it shows faster cuz it's loose. But if u exercised n worked on ur abs n they r strong then it will be the same as a 1st timer. This is my 3 n I exercises n had a six pack after my pregnancies so even on my 3rd I didn't show til 25 weeks. So it depends on how tight ur abs muscles r
I showed at 10 weeks the first time, 7 weeks the second time and am just starting to show now at 5weeks 5days.
Started showing at 11 weeks my second time. Didn't show until 20 weeks the first time around.
The second was showing so much sooner. My belly looks like 6 months while i was just 3. People start asking, that never happend by my first pragnancy. Closer to the duedate, its becomming to be the same belly, it stopt growing (luckely).
But probably because I got pregnant right after my first
I started showing at 6 weeks