Why so tight

[Tamtui]

I do a lot of physical activity. Especially yoga and martial arts, but lately I've been noticing my abdominal muscles are tight almost all the time! I'm usually a very flexible person, and I thought your muscles were supposed to loosen up during pregnancy, so I'm confused about why this happens.
I thought I'd be more flexible, not less.
Do only some pregnant women have relaxin?

[Darafina]

I was hard as a rock and as a big basketball when I was pregnant with my first child.  Everyone was so surprised at how hard my stomach was. I was never loose at all.  The more my stomach stretched, the harder the tummy was. I was surprised I didn't get any stretch marks at all from it because my stomach was so tight and stretched to the max.  I think after your first child, your stomach will loosen up more and adjust the changes better.  My stomach is softer now and doesn't feel hard at all. I used to be a gym spinning junky and I did a lot of pilates too. I wasn't too flexible though.  LOL.

[SunWorshiper_26]

All have relaxin but different amounts and it kicks in at different times. Mine abs are still really tight at 26 weeks it's different for everyone