Strengthening your legs and hips will prepare your body to carry the added weight of pregnancy and help you maintain good posture.
Holding 3-pound dumbbells, stand with feet farther than hip-width apart, toes facing forward. Lift your right knee to hip height as you raise both arms in front of you to shoulder height, palms facing down. Lower your leg and squat, bending your knees as you sit back into your hips and lower your arms to your sides. Return to the starting position and repeat knee lift with left leg. Do 6 reps, working up to 12.