In the first trimester of your pregnancy, a wide range of symptoms are possible. While you're not yet feeling heavy or weighed down by a big belly, you may feel nauseated and fatigued. Some lucky ladies don't suffer from any of these common woes, though, and barely notice their pregnancies during the first trimester. If you're a runner, you may want to keep up your exercise routine to feel healthy and simply feel like yourself. A good rule of thumb is to always consult with your doctor about exercise during any stage of pregnancy to be sure that it's safe.

Your Running Habits

According to BabyCenter.com, running in the first trimester is probably safe for most women, barring any other health concerns, as long as you ran regularly before you got pregnant. Even if you are a runner, it's not the time for strenuous training or really difficult running, such as a marathon. If you haven't been consistently running before pregnancy, consider choosing another exercise until after the baby is born.

Exercise Concerns

If you're not fit for it and push yourself too hard during a run, you could overheat and potentially pose risks for the developing fetus. Pregnancy also relaxes your joints, which take a beating when you're running. Pregnant women are at a greater risk for sustaining a running injury, so be wary of running too much or too hard. If your doctor and physical fitness level allow you to run safely in your first trimester, remember to drink plenty of water to ward off dehydration.

Running Risks

Several factors and complications can make running unsafe for women in their first trimester, even if they're in great physical shape. Women who experience any vaginal bleeding or early contractions, have pregnancy-induced hypertension or experience early rupture of the amniotic sac may not be able to continue running during pregnancy.

Alternatives to Running

Exercise and regular physical activity can be very helpful in promoting a healthy pregnancy and in coping with the physical and emotional challenges of pregnancy. Instead of running, consider prenatal yoga, walking and swimming. You may want to use exercise equipment, such as an elliptical machine or stationary bike, to help you stay fit while protecting your baby and your body from potential harm.