Healthy, Fit, Active mama's.... what are your BEST pregnancy workouts?!! Can I still try to tone my…

Healthy, Fit, Active mama's.... what are your BEST pregnancy workouts?!! Can I still try to tone my stomach while pregnant as long as I'm not straining myself?? I mostly stick to running and hiking and do lots of leg workouts but I've gained 4 lbs this week and my stomach is feeling flabby! I have seen mama's with abs on their bumps that didn't start their pregnancy with a six pack, so I know it's possible! (not exactly what I'm going for but definitely want to be toned and have a healthy delivery with a quick recovery)