Running is the exercise of choice for many women. It can help you maintain a healthy body weight, since you burn an average of 100 calories for each mile you run, Elizabeth McLeod Sadler writes for Vanderbilt University's psychology department. It also strengthens your heart, improves lung function and lowers blood pressure. If you become pregnant, you might worry that continuing to run will harm your baby or even cause a miscarriage. Fortunately, you might not have to give up running to have a successful pregnancy.
Exercise and Pregnancy
Exercising for at least 30 minutes a day offers a number of benefits during pregnancy, according to the American Congress of Obstetricians and Gynecologists. It can improve your sleep, help prevent gestational diabetes and reduce some common discomforts of pregnancy, such as constipation, back pain and bloating. Running -- if done in moderation -- can be a safe exercise during pregnancy as long as you were a runner before becoming pregnant and discuss the safety of running with your doctor.
Running and Pregnancy
You may need to modify your routine -- even if you ran regularly prior to becoming pregnant -- to prevent injury to yourself or your baby. Since your joints loosen and your center of gravity shifts during pregnancy, run on flat pavement or a track to lower your risk of falling. Listen to your body, particularly during the third trimester. Don't run if you feel too tired and slow your pace to a fast walk toward the end of your pregnancy. Stop running before you become breathless or exhausted. Pushing yourself too hard may reduce the amount of oxygen your baby receives.
Even if you follow the precautions for running during pregnancy, some evidence exists that running during pregnancy could increase your miscarriage risk. Study results published in 2007 in the "British Journal of Obstetrics and Gynaecology" found an association between high-impact exercise -- including running -- in early pregnancy and miscarriage. Engaging in high-impact exercise between 75 and 269 minutes per week resulted in a hazard rate for miscarriage of up to 4.7 times that of women who didn't exercise. The greatest miscarriage risk occurred before 14 weeks, and the association disappeared after 18 weeks. Women who exercised more than 7 hours a week had 3.7 times the risk of miscarriage as women who didn't exercise. However, the study's researchers admit that asking women to recall their exercise habits might have reduced the accuracy of their findings. They also pointed out that more research was needed before women should be discouraged from exercising in early pregnancy.
Stop running immediately and contact your doctor if you notice warning signs that can indicate a serious problem for you or your baby. Difficulty breathing, a headache, chest pain, dizziness, or pain or swelling in your calf muscle suggest you are pushing yourself too hard. Vaginal bleeding, leaking fluid from the vagina, contractions -- which can signal preterm labor -- or a decrease in fetal movement may indicate a threat to your pregnancy.