Bridges

• Bridge poses are an effective exercise for women who want to work multiple core muscles at once, according to the Mayo Clinic. Bridges are performed by lying flat on your back with bent knees and lifting your buttocks toward the ceiling. Poses are then held for 10 to 20 seconds before lowering.
  
  

Crunches

• Crunches have long been a go-to exercise for working the core, especially for women who aren't able to do full sit ups. Lying flat and lifting the shoulders to a 45 degree angle will work the muscles without pulling the lower back.
  
  

Side Twists

• Side twists are useful in fighting oblique or"muffin top" fat. Standing side twists are executed by placing your arms behind your head and twisting your core from right to left. Fitness Magazine suggests taking both hands up to one side like swinging a baseball bat, which will target the obliques, arms and back.
  
  

Knee Lifts

• Knee lifts aren't just for the rear and thighs; knee lifts also work the lower abs, which helps to pull in the extra skin after pregnancy. They can be done standing or lying down. When pulling the knee up, the foot should be parallel to the floor or wall.