Go ahead, have a ball

Before
Prior to pregnancy, you probably used an exercise ball at the gym or in Pilates class to tone your core. Exercises incorporate these balls because they really engage your abdominal muscles, resulting in a firmer midsection and better posture. Try sitting on one at your desk instead of a regular chair, and feel your muscles work.
During
Many moms like to sit on a birthing ball during labor to take pressure off their lower backs. Sitting on it while rocking your hips back and forth or moving your pelvis around in figure eights may make contractions more bearable. Bouncing up and down gently while sitting on the ball can help distract you from the pain too.
After
Once your doctor gives you the green light postpartum, begin light exercises on the ball. Simply sitting on it daily will start to get those abdominal muscles back into shape. And when you’re ready, you can try modified sit-ups. Just remember to start slowly and tailor your routine to your own abilities.