Fanatics and runners who become pregnant for the first time may be shocked to learn that the bible for all mothers-to-be, What to Expect When You’re Expecting, has a chapter on exercise that says running for more than 2 miles while pregnant is a no-no. Two miles? For a lot of people, that’s a warm-up.

Runner’s World’s Running for Pregnant Women, on the other hand, tells stories of women who have run marathons while pregnant. That would be 24.2 miles past the other book’s recommendation.

When it comes to fitness and pregnancy, there’s a lot the experts don’t agree on.

Many articles and books say cardiovascular exercise should not exceed 30 minutes at a time and heart rate should be kept under 140 beats a minute. Many experts also seem to suggest that some particular exercises should be avoided: full sit-ups, lunges and bench presses, for example.

But some of those recommendations may be outdated, says Dr. Raul Artal, chairman of the department of Obstetrics and Gynecology at St. Louis University. For the past 25 years, Artal has written the exercise guidelines for the American College of Obstetricians and Gynecologists.

“We abandoned some of those recommendations 20 years ago,” he says. “A lot of people are working with old information. The college and I are really publicizing the fact that pregnancy should not be a state of confinement. ...

“Pregnant women should not be deprived of the opportunity to derive health benefits from physical activity. So what we tell pregnant women is that there is no reason to restrict physical activity, unless there are obstetric or medical complications.”

Watch temperature
Under the current American College of Obstetricians and Gynecologists guidelines, pregnant women are encouraged to engage in 30 minutes or more of moderate exercise on most, if not all, days of the week.

But what exactly does “or more” mean? Artal says that if a woman physically can do it, it’s possible to continue even strenuous exercise for long periods of time throughout pregnancy. However, he says, there are certain precautions.

“One big concern in engaging in strenuous exercise is that if you do this early in pregnancy, you may cause birth defects if your core temperature rises to unsafe levels,” he says.

That temperature has to exceed 103 degrees, but if you are running a marathon, it can happen.

Though he has seen plenty of pregnant athletes continue to exercise strenuously, Artal says you get the same benefits during pregnancy by exercising moderately. He recommends that his patients stay away from strenuous activity unless necessary (for instance, if they are professional athletes). “What I tell them is to do the talk test. If they can converse normally while exercising, they are fine.”

Debbie Zeiss, a physical therapist who teaches a prenatal exercise class at St. John’s Mercy Medical Center in St. Louis, agrees that some of the information on pregnancy and exercise can be misleading.

“There’s a lot of literature out there in books and on the Internet,” she says. “But what I tell women is to think of themselves, what’s appropriate for their body. You know yourself the best. A lot of people are coming into class with information that may not be right for them.”

When it comes to her patients, however, Zeiss says she errs on the side of caution. “Generally, whatever a person was doing before, they can continue doing while they are pregnant.” She adds that a person new to exercise should be sure to take it slow.

But every pregnant woman should be walking, Zeiss says, unless some complications prevent it.

“I tell my patients to live a normal life,” Artal says. “Women can engage in a variety of recreational activities. It becomes a matter of judgment.”

He says the only thing that’s an absolute don’t is scuba diving, because it may cause bubbles to form in the bloodstream that can threaten the baby.

There are benefits
Contact sports are a gray area. “Contact sports become a matter of judgment,” he says. The American College of Obstetricians and Gynecologists says “each sport should be reviewed individually for its potential risk, and activities with a high risk of falling or those with a high risk of abdominal trauma should be avoided during pregnancy.”

Artal tells the story of someone who once asked him if skydiving is safe during pregnancy. “I said, ‘I don’t know about for pregnancy, but I think it’s kind of dangerous in general.’ “

Zeiss says that even full sit-ups are OK for most women.

“A lot of women think they can’t do ab exercises, but most can,” says Zeiss. The women who can’t are those with a separation of the ab muscles, called diastasis recti, which may occur during pregnancy. “We teach them how to look for it, and if the separation is less than two finger widths, they can do sit-ups with the knees bent.”

Artal notes there are many benefits of exercising while pregnant: prevention of obesity, prevention of gestational diabetes, possible prevention of high blood pressure, establishment of good health for a lifetime and good psychological well-being.

Swimming is almost universally recommended by obstetricians. “I even had one woman who was pregnant with triplets, and her doctor said this is absolutely the only kind of exercise she can do,” said Maggie Daily, who teaches pre- and postnatal water exercise at a St. Louis YMCA.

Daily says it’s the buoyancy of the water that makes it so effective. “It protects your joints,” she says. “The ligaments loosen in pregnancy, and land exercise is not as comfortable, but if you do exercise in water, the ligaments are protected. And if you are in deep enough water, you are only 10 percent of your body weight. That’s a big relief for pregnant women.”

Tips for pregnancy workouts
#  Eat before a workout. When you are pregnant, you are susceptible to low blood sugar.

# Be sure to stay well-hydrated.

# Accept that you will slow down; you are carrying additional weight.

# If you top 140 pounds, your joints can take a pounding with any kind of impact exercise, making you more susceptible to injury.

# Be careful about lying on your back. In some women, the uterus impinges on the blood vessels, so lying on the back for long periods is a bad idea. However, most ab exercises only take a few minutes.

# Be aware of lax joints. Your body releases a hormone called relaxin to help loosen your joints during pregnancy. Over-stretching or straining can cause injury.

# Be aware that your balance may be off, and take extra precautions. For example, use a chair when doing a yoga pose on one leg.

# Avoid exercise in hot, humid conditions to avoid overheating.

# Compensate for exercise by taking in more calories.

# As you get bigger, you put more stress on the pelvic floor while doing weight-bearing exercises, so be sure to do pelvic-floor exercises, such as Kegels.

# Avoid motionless standing as much as possible; it is associated with a decrease in how much work your heart can do.

# After delivery, ease back into exercise.

Sources: Dr. Raul Artal, physical therapist Debbie Zeiss, American College of Obstetricians and Gynecologists

Warning signs
#

These signs indicate a pregnant woman should stop exercising and seek medical attention:

# Vaginal bleeding

# Dyspnea (abnormal or uncomfortable breathing) before exertion

# Dizziness

# Headache

# Chest pain

# Muscle weakness

# Calf pain or swelling

# Pre-term labor

# Decreased fetal movement

# Amniotic fluid leakage

Source: American College of Obstetricians and Gynecologists