Many women enjoy a healthy lifestyle that includes regular exercise and a good diet. It can be tough to maintain that lifestyle when she becomes pregnant, especially during the later stages. But it is possible, and in fact preferable, to maintain an exercise regiment at least up until the last month.

Pregnancy brings many changes. Hormone levels go wild, you gain weight and (later) movement becomes increasingly difficult. Changes in the level of progesterone, estrogen and others produce softening of the ligaments around joints. Strain on internal organs, the back and legs is inevitable. At the same time, you'll put on almost 30 lbs. Go easy.

Sometimes a general malaise sets in. Regular, appropriate exercise can help relieve much of that and help put your body in the best shape possible for labor. That optimizes your comfort and your growing baby's health.

The first step is to adopt a kind of Hippocratic Oath of Pregnancy: First, Do No Harm. That ancient principle from the Greeks is still valid, more so during pregnancy. Some women are used to running five miles, doing every station at the weight machine or performing Pilates an hour a day. That will have to change fairly quickly.

But maintaining a good exercise regimen is still possible, just change your workout to fit your changing body. Eliminate crunches or any other form of exercise that stresses the abdominals or back. Go with lighter weights. Avoid jerky movements and forego squats which can separate the placenta from the uterus.

Breathing properly during exercises performed while pregnant is essential. Correct breathing technique anytime is important, but you're now breathing for two. The baby receives oxygen through the umbilical and keeping the blood fully oxygenated is imperative.

Keep in mind that your resting heartbeat will increase by about 8 beats per minute during the first few weeks. Blood volume increases substantially as you progress. Factor that in when you consider any cardio exercise.

Hydrate at an appropriate amount throughout the day. That means small sips over a longer time frame, rather than large intake at a given time. Eating should follow the same pattern - four to five small meals per day is preferable to three larger ones.

Before beginning a workout, warm up gently. Perform easy stretches and be prepared to rest often for a few minutes at a time. Light cardio is the key to a healthy circulatory system, so important during these months.

Pregnancy shifts your center of gravity forward, stressing the spine and back muscles. To ease that aching back, swimming is one of the best forms of exercises. It also gives a very low stress but active cardio workout.

Yoga is a favorite for many. It helps achieve peace of mind and provides gentle movements that provide the needed stretching, while building good leg and arm strength. It gives also low impact on the back.

With a good program, you'll reduce cramps, improve circulation and increase energy. You'll lower your resting heart rate and keep fit.

If you feel any dizziness, swelling or experience any kind of vaginal bleeding or discharge discontinue at once and consult a medical professional.

Before beginning any exercise regimen it's vital that you talk with your physician. It's great to get more than one opinion, but your OB/GYN (obstetrician/gynecologist) can help you devise a program that is great for you and your baby.