Running or jogging during pregnancy can be a great aerobic exercise, as long as you take a few precautions.
First, it's important to check with your doctor or midwife so they can give you the "all clear."
Usually, if you ran regularly before getting pregnant, it's fine to continue as long as you're still feeling okay. The key is to listen to your body and, at the first sign of discomfort, to slow things down.
The first trimester is a crucial time when the baby's major organs are forming and overheating is an issue. If your core temperature gets too high, it could cause problems with the baby, so be sure to take it slowly on hot days and drink plenty of fluids.
You may find that you're short of breath in the first and third trimesters and will have to modify your exercise routine accordingly. Eventually, your new shape may make running or jogging uncomfortable, in which case walking or power walking are great alternatives.
It's not a good idea to start running if you weren't running on a consistent basis before getting pregnant. Pregnancy is also not such a great time to start training for a marathon or any other race–save that for after the baby is born when you're ready to work toward getting back in shape.
Andrea Grace is the president and creator of Mommy and Baby Fitness pre- and post-natal fitness programs with locations across North America. She is a CanFitPro and ACE certified fitness professional with specialty certifications in pre-and post-natal and children's fitness.mommyandbabyfitness.com