The American College of Obstetricians and Gynecologists advise pregnant women to stay active. If there are no complications or problems, exercise for 30 minutes five or six times a week is advised.

The exercise should be moderate. Avoid high contact or sports and activities with a risk of falling. Elevating heart rates to high levels is not advised. Too much stress on the mother's heart and lungs can compromise the unborn child.

Changing hormones can also put the woman's body at risk for muscle, tendon, or joint injury.

The weight of the fetus combined with hormones designed to loosen the pelvic muscles and joints can lead to pelvic floor problems.

Running, hopping, or jumping activities can make it worse. The result can be long-term problems with urine leaking called incontinence.

Marathon running is not advised without a physician's approval. Talk to your obstetrician before starting your training.