Can I do ab exercises while I'm pregnant, and if so, what's the point?
While doing abdominal exercises now won't give you abs of steel, they will strengthen your core (and back) and make you aware of all the muscles you will use during the pushing phase of labor. Strengthening your core muscles also can help relieve pregnancy-related back pain.
Even if you're having a complication-free pregnancy, exercise caution as you work your already-taxed ab muscles. "After four months, you have to be more careful about which exercises you do, as you could pull a muscle," Downs cautions. For this reason, you should avoid twisting movements. (You also should avoid moves that require you to lie on your back in the second and third trimesters; see the question.)
Here's a safe, effective ab move: Sit upright with your hands on your belly. Take a deep breath in through your nose, then exhale through your mouth as you draw your ab muscles in toward your spine. Do 10 repetitions and build up to 20 reps, 3 times a day. This helps strengthen your abdominals, especially the deep transverse muscle, which helps support your lower back throughout pregnancy and assists in the pushing phase of labor.