Follow these tips for safe and healthy fitness: 
•    When you exercise, start slowly, progress gradually, and cool down slowly. 
•    You should be able to talk while exercising. If not, you may be overdoing it. 
•    Take frequent breaks. 
•    Don't exercise on your back after the first trimester. This can put too much pressure on an important vein and limit blood flow to the baby. 
•    Avoid jerky, bouncing, and high-impact movements. Connective tissues stretch much more easily during pregnancy. So, these types of movements put you at risk of joint injury. 
•    Be careful not to lose your balance. As your baby grows, your center of gravity shifts making you more prone to falls. For this reason, activities like jogging, using a bicycle, or playing racquet sports might be riskier as you near the third trimester. 
•    Don't exercise at high altitudes (more than 6,000 feet). It can prevent your baby from getting enough oxygen. 
•    Make sure you drink lots of fluids before, during, and after exercising. 
•    Do not workout in extreme heat or humidity. 
•    If you feel uncomfortable, short of breath, or tired, take a break and take it easier when you exercise again. 

Stop exercising and call your doctor as soon as possible if you have any of the following: 
•    Dizziness 
•    Headache 
•    Chest pain 
•    Calf pain or swelling 
•    Abdominal pain 
•    Blurred vision 
•    Fluid leaking from the vagina 
•    Vaginal bleeding 
•    Less fetal movement 
•    Contractions