2. Side-Lying Crunch: Lie on your left side, knees bent at a 30-degree angle to your hips. Roll over to the right only enough to lift your knees about 6 inches off the floor, your body weight resting on the back of your left shoulder and shoulder blade. Place both hands behind your head, fingertips touching but not clasped, elbows open. Curl torso up on the diagonal, bringing your breastbone toward your right knee. Your left shoulder will lift only slightly off the floor.
At the top of the movement, reach both arms forward toward your knees, curling up a little higher. Place hands back behind head and lower to starting position, then repeat. Do 1 set of 6 reps, then switch sides, progressing to 12 reps for all 3 trimesters.
Note: You probably should be able to perform this exercise comfortably into the beginning of your last trimester. If you have a diastasis, lift your torso directly upward, not on the diagonal. As your pregnancy progresses, and when you begin to exercise postpartum, help pull yourself upward by holding your thighs. You also can add a second set postpartum when the first is no longer challenging. Strengthens abdominals.
3. Bridging with a Curl: Lie face up on the floor with your heels on the seat of a chair, knees bent. Position yourself so your hips are about 6–8 inches behind your knees. Relax your arms by your sides. Keeping your lower back in contact with the floor, curl your torso upward, bringing ribs toward hips, until shoulder blades clear the floor.
Holding this position, tilt your pelvis under, press down with your heels for leverage, and use your abs to lift your pelvis off the floor until your legs and hips form a straight line. Lower buttocks to the floor, then lower upper torso. Do 1 set of 8–12 reps; when that’s comfortable, add a second set of 8 reps and build to 12 reps. Strengthens abdominals.