It is still important to exercise during pregnancy for cardiovascular health, endurance and strength. A pregnant woman should avoid lying on her stomach for over five minutes. Strenuous exercises or overheating should be avoided.
Optimal exercises for pregnancy include mild aerobics or swimming. Cardiovascular equipment with steady motions is also recommended. Running on an incline on a treadmill or very fast stair climbing are contraindicated.
Lifting weights is fine as long as they are not very heavy and it is not strenuous. During the second and third trimester, weights should be lifted only while sitting.
Abdominal exercises are out. Abdominal muscles are used as secondary muscles while walking so walking is a good exercise for them.
These symptoms indicate that you should stop. If they persist, call a physician: dizziness, shortness of breath, faintness, vaginal bleeding, blurred vision, difficulty walking, or contractions.
Some of the information for this blog was obtained from http://www.babycenter.com/refcap/pregnancy/pregnancyfitness/758.html and http://www.babycenter.com/refcap/pregnancy/pregnancyfitness/7878.html .