Your third trimester of pregnancy is exciting and tiring at the same time. Your first trimester was tiring. During the second trimester you regained your energy and lost the morning sickness. Now you are larger, have an altered center of gravity and are beginning to get tired and fatigued once more. And yet, your doctor continues to encourage you to exercise in third trimester.

You say "WHAT?" But your doctor is on the right track. Women who have exercised through their pregnancy report they have generally easier deliveries. Does this mean they feel less pain or discomfort? No. But women who exercise up to the time of delivery have more endurance and better pain tolerance. They have an easier time accommodating to the new sleepless schedule when they go home with the new little one.

So what type of exercises work best for a woman who is carrying enough weight out front that her center of gravity is different, her balance is affected and her ankles are swelling with each passing day? How to stay in cardiovascular shape, keep muscles moving and pump up your respiratory rate to stimulate your lungs?

During the first trimester women who were exercising can continue their standard routine and women who weren't exercising should start a simple routine they can conceivably continue through the pregnancy. In the second trimester the exercising routines should have a goal of only slightly improving physical endurance and ability since the woman's body is already working overtime to develop this new little baby.

During the third trimester all the women must take a good look at the type of exercise program they are incorporating into their routine. The exercises they choose must accommodate their increasing size, changing center of gravity and increased potential risk to the baby as the belly grows larger and larger. There are some excellent choices that don't require much learning or even too much equipment.

Stretching is an exercise. In fact, done correctly, stretching will help your muscles to accommodate well to labor and delivery. However, because of the increasing amounts of 2 hormones, progesterone and relaxin, you also increase the potential of overstretching joints. Hormones are released in the latter parts of your pregnancy which increase the amount of 'stretch' to your tendons and ligaments. This stretch is necessary to accommodate the stretch your pelvis must go through to help your baby be introduced to the world.

Because of the increased amount of stretch to your ligaments and tendons exercises that have a high impact to your joints may actually cause more damage than they help. For instance, running, jogging and trampoline work will actually cause the hips and knees to be at a higher risk of damage during the workout.

Exercises in third trimester that are good for you and your baby are exercises such as walking, rowing, slow stair climbing on a machine, biking on a stationary bicycle and low impact aerobics that doesn't involve knee bends or stress to the hips.

With the increasing number of exercise gurus, tapes, DVDs and CDs there are also an increasing number of choices for women who are in their third trimester of pregnancy to maintain or attain a level of physical fitness that will help with labor and delivery.