In times past, women were often advised to avoid strenuous activity and stay off their feet while pregnant. But modern research has shown that pregnant women are not as fragile as it was once believed-and that exercise may actually be beneficial for both baby and mother-to-be. Here are a few body building tips and guidelines for pregnant women.

If you're new to body building, now isn't the time to start. Most of these tips are for women who are already accustomed to a body building routine. If your body isn't used to exercise, avoid starting a strenuous workout regime. Instead, choose a mild, low-impact aerobic activity such as walking or swimming-and set a slow pace; don't push yourself. Your heart rate and body temperature must not be allowed to reach elevated levels.

Keep your pulse low and avoid overheating. In general, pregnant women are advised to keep their pulse below 140 beats per minute and their body temperature below 100°F (38°C). When lifting weights, this means you'll have to rest longer between repetitions; some experts suggest a rest time of approximately two minutes. It also means you'll need to drink plenty of water to stay cool and hydrated.

You should also monitor your heartbeat during exercise. If you don't have an electronic device to do this for you, simply count how many times your heart beats in ten seconds while exercising-and then multiply by six. This will tell you how many times your heart is beating per minute.

Don't do abdominal exercises. When you're pregnant, you should avoid doing exercises that put strain on the abdominal muscles. This includes any exercises that specifically target these muscle groups, and it also includes exercises that target multiple muscle groups, including the abs. Abdominal muscles are often used to balance your body during squats and other freestanding exercises, and these should be avoided while you're pregnant.

Avoid muscular failure. Hormonal changes during pregnancy make it easier for your muscles to tear. While pregnant, it's best to avoid exercising to the point of muscular failure, or the point you are no longer physically able to perform an exercise. Reduce the strain on your muscles by performing fewer reps per set and fewer exercises per body part than you're accustomed to. At the beginning of your pregnancy, start with the weight you're used to-and reduce your weights as your pregnancy progresses.

Don't exercise while lying flat on your back or stomach. These positions can reduce blood flow to the uterus, which could be dangerous for the baby. Stay away from flat bench presses, lying leg curls, and other exercises that require you to lay on your back or stomach, and replace them with sitting or standing exercises that target the same muscle groups.

Pay close attention to form and reduce weight when needed. When you're pregnant, your joints and ligaments begin to loosen in order to prepare your body for birth. This puts you at greater risk for joint trauma and soft muscle injuries. During pregnancy, it's especially important to pay attention to form while performing body building exercises-a mistake is more likely to lead to injury. This is also why it's important to reduce the amount of reps and possibly the weight you use to avoid putting too much strain on your joints, and to use machines rather than free weights.

Avoid exercises that require balance. A fall can be dangerous for both mother and child. That's why it's so important to avoid doing exercises that require balance when you're pregnant. Avoid lunges, squats, and other standing exercises that may present risk of falling. Instead, use machines that help you target the same muscle groups from a sitting position.

Look for back support. When working with free weights or machines, look for a seat that supports your back. Avoid doing exercises that target the lower back muscles, as well.

Use machines, not free weights. Free weights require balance and draw on multiple muscle groups, while machines isolate muscle groups and lock you into position. Under normal circumstances, free weights often provide a better overall workout than machines do. But when you're pregnant, there are many reasons why machines are better for you than free weights.

Machines protect you by supporting you during exercise, so there is less risk of losing your balance and falling. Machines isolate muscle groups, so you can more easily avoid using your abdominals while using machines than with free weights. Machines lock you into a safer position, so you're less likely to strain your joints.

There may be some situations where a certain machine is less safe than a certain free weight exercise, however-such as flat bench press machines, which require you to lie on your back and may not have a light enough weight option available. To get the same results more safely, use light barbells in a sitting or inclined position.

Remember to breathe. While body building, it's crucial to maintain a steady, even pattern of breathing. This is true under all circumstances, but it's especially important during pregnancy. When you don't breathe, your baby doesn't breathe-and holding your breath could hurt the baby. Avoid exercises that make you short of breath; keep a slow, steady pace that allows you to breathe evenly.

Talk to your doctor. This is general body building advice and should not be taken as medical advice targeted to you. Be sure to talk to your doctor about your workout routine before starting, and don't perform any exercises your doctor tells you to avoid.

Body building can be a safe and healthy way to stay fit while you're pregnant. Follow these tips and talk to your doctor before starting your exercise regime, and you're likely to have a fit, healthy pregnancy.

About the author

Jean Lam is the webmaster of Body Building Resource which provides articles on weight training, nutrition and fitness, body building book and DVDs.