Are you looking for gynaecologist near you ? Best gynaecologist in Pune ? What precautions should I take when exercising during pregnancy? Drink plenty of water before, during, and after your workout. Signs of dehydration include dizziness, a racing or pounding heart, and urinating only small amounts or having urine that is dark yellow. Wear a sports bra that gives lots of support to help protect your breasts. Later in pregnancy, a belly support belt may reduce discomfort while walking or running. Avoid becoming overheated, especially in the first trimester. Drink plenty of water, wear loose-fitting clothing, and exercise in a temperature-controlled room. Do not exercise outside when it is very hot or humid. Avoid standing still or lying flat on your back as much as possible. When you lie on your back, your uterus presses on a large vein that returns blood to the heart. Standing motionless can cause blood to pool in your legs and feet. These positions may cause your blood pressure to decrease for a short time.