Rare is the pregnant woman who can run a full marathon the day before giving birth, as Illinois mom Amber Miller did in October. But while you're not expected to be pounding the pavement shortly before your delivery, it is important to break a sweat while pregnant.

In a recent "Caller 911" episode of Daily Dose With Jillian Michaels, Jillian dished advice on the best approach to exercise before and shortly after giving birth to a fit mom of two kids with a third on the way. Common wisdom holds that women should wait six weeks post-partum before hitting the gym, but Jillian says it depends on each individual pregnancy and the advice of the mom's physician.

"With every pregnancy, it’s unique to each woman," Jillian says. "What she goes through during the pregnany, during the birth, all of these things are going to impact how early she should be up and exercising."

Generally, she says it's best to talk to your doctor and create a plan that's right for you. Don't compare yourself to other mothers, particularly celebrity moms who appear to shed baby weight in a matter of days, Jillian says.

"The safest way to handle baby weight is not to gain it," Jillian says. "They say a 25- to 40-pound weight gain is the best bet. If it works out otherwise, no shame in that, but then allow yourself some extra time after the baby it get back in shape."

The Best Exercises During Pregnancy

If you were already exercising at a high intensity before you were pregnant, keeping up with your routine won't harm the baby's health, a new study from Johns Hopkins University in Baltimore found. In the study, researchers found that healthy women should continue with their regular exercise routines and women who are not regular exercisers should be encouraged to start moderate exercise programs for a healthy pregnancy. These findings are in line with recommendations from the U.S. Department of Health and Human Services that say healthy pregnant women should complete two and a half hours of medium intensity exercise every week.

Still, consult with your doctor before starting any exercise routine, and if you do decide to try new exercises, proceed with caution.

"This is not the time to throw around heavy weights," Jillian says. "Don’t try to lose weight. Let's ride that middle line where we don’t need to be precious, but we don’t need to prove a point with your pregnancy either."

Generally, it's also best to avoid exercises that are compressive on the spine, such as military or incline presses or sit-ups. Jillian says that walking on an incline is one of the best exercises a pregnant woman can do because it's fairly low-impact, yet burns fat and calories. Many pregnant women also enjoy water workouts or prenatal yoga and Pilates classes that stretch the muscles, tone, and may ease pregnancy symptoms, such as leg cramps and sore shoulders.

The Importance of a Fit Pregnancy

Your health may do more to influence the future health of your child more than you might think. Study after study — including a recent report that linked a high maternal weight to autism risk in children — has found that your weight and diet while pregnant can seriously impact your child's risk for heart disease, obesity, diabetes, and other conditions later in life. Overweight moms are also far more likely to give birth to large babies, which increases the risk for complications during birth.

But the good news is, even if you are currently overweight, there are steps you can take while pregnant to protect your health and the health of your baby. Eating a nutritious, calorie-controlled diet during pregnancy can drastically reduce your risk for complications, a review of 44 studies that was published online in the BMJ found. A healthy diet was found to be more helpful than exercise alone while the combination of diet and exercise was found to be the best bet for a healthy pregnancy.

Overall, it's a matter of finding what works for you.

"There's no one-size-fits-all approach to [exercising while pregnant]," Jillian says. "Consult your physician, and don’t compare yourself to others." www.everydayhealth.com/fitness/jillian-michaels-on-exercising-while-pregnant.aspx