The instructor may be so strong herself from many years of dance or athletic training, that what she perceives of as beginning or intermediate level, may actually be too advanced for the average pregnant woman. Seated upper body exercises with no back support. Floor work requiring you to be on all fours or standing with one leg lifted. Exercises utilizing weights. During pregnancy your center of gravity is constantly shifting and changing as the baby grows.
Postural changes can become a daily occurance.
Without correct posture, your workout will automatically become unsafe. Once you've chosen the right video for you, keep in mind that your workout routine is going to be identical each time you use it. Exercise on nonconsecutive days, three times per week, stay well-hydrated, wear appropriate workout shoes and workout clothing that does not constrict your belly. Always check with your doctor first before beginning any exercise program and be sure to add in your pregnancy-specific exercises as well.