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Debunking myths about pregnancy hazards

We’ve been told that when pregnant, women shouldn’t stand for very long periods of time. True or false?True. Studies have shown that standing more than five hours can increase prematurity. I should point out that for anyone, standing without a break for five hours is a long time. In pregnant women, this continued upright position causes pooling of blood in the lower extremities, and that means
/ Source: TODAY

We’ve been told that when pregnant, women shouldn’t stand for very long periods of time. True or false?

True. Studies have shown that standing more than five hours can increase prematurity. I should point out that for anyone, standing without a break for five hours is a long time. In pregnant women, this continued upright position causes pooling of blood in the lower extremities, and that means that less is available for the uterus. 

Moreover, the enlarging uterus and fetus press on the vessels coming out of the pelvis and add insult to injury by diminishing return of blood from the legs to the heart. All of this can also lead to increase in clots, dizziness and fatigue. It may also compromise the blood-driven nutrition to the developing fetus. For women who work outside the home in jobs that require long hours of standing, the American Medical Association suggests modification so that a break is taken every four hours. They also suggest that work positions be varied (from standing to sitting to walking around). 

This admonition against standing for more than five hours should of course apply not only to women who are working outside the home, but also to those who do their work at home, managing their household chores and children. They all should be off their feet and resting every few hours.

What about lifting heavy objects? Is it true a pregnant woman should not lift anything heavier than 25 pounds?

Not completely true….but not false! Late in pregnancy a woman’s ability to safely lift a load decreases, mostly because her center of gravity and balance have changed and additionally because the hormones of pregnancy have caused her connective tissue, ligaments and tendons to soften. So if she lifts a heavy load she can injure herself, but will probably do no harm to the pregnancy or the baby. There are no studies that show that lifting more than 25 pounds has an effect on birth weight or prematurity. 

The current recommendation is that the maximum load a pregnant woman should lift in late pregnancy should be reduced by 20 to 25 percent from that which she was able to lift in her pre-pregnancy state. 

What about strenuous physical work? Shouldn’t the pregnant woman decrease her workload or abstain from strenuous activities?

Probably false, but before we go any further, let me just state that it’s difficult to give precise, medically based evidence on what strenuous work and length of work (be it a job outside or inside the home) do to pregnancy outcomes. Many studies have been carried out, but they have encountered significant problems reaching conclusions because the term “work” has so many definitions. There are also a huge number of variables such as where the work is done, stresses associated with the work (or after work), psychosocial and economic factors of the job and the state of the pregnant woman’s life. A salesperson, a construction worker, a chef, a surgeon and a homemaker may have strenuous jobs, stand a lot and feel exhausted at the end of the day, but obviously there are tremendous differences. 

Also, we have to remember that for some, work may entail additional risk factors such as extreme physical exertion, heat, noise and environmental toxins. Nor does work in pregnancy necessarily mean outside the home; it can be just as (or more) strenuous in the home, especially if a pregnant woman has to care for other children and has no help or emotional support.

Studies that have tried to look at a combination of all these factors show a general increase in prematurity and a slight decrease in birth weight with strenuous work that requires long hours. But the same studies also show that taking a defined rest period every four hours and having time off during the month decrease the incidence of pre-term birth in women, especially if the job requires manual labor. 

What about standing, lifting or exertion in high-risk pregnancies? Shouldn’t women with high-risk pregnancies avoid these activities?

True. If a woman has a history of previous pre-term birth, multiple miscarriages, known abnormalities of her uterus or cervix (such as an incompetent or shortened cervix) or has underlying heart or lung problems, she should limit her activity. 

And if, in her current pregnancy she had has bleeding (especially after the second trimester), has been diagnosed with a small-for-gestation pregnancy, low levels of amniotic fluid (oligohydramnios), multiple gestations (twins or more) or had an episode of early contractions, she is advised to restrict these activities. We’re just not sure how much to restrict them. Recent reviews [Cochrane reviews] did not find enough evidence to support hospitalization or bed rest for pregnant women with multiple pregnancies, bed rest at home or hospitalization to prevent pre-term birth for singleton pregnancies in women who are high-risk for preterm labor or bed rest in the hospital for women with poor fetal growth. 

But most physicians will, for women with these conditions, suggest that they “stay at home and rest as much as possible.” Certainly strenuous work should be avoided.

What about heat? Is it true that pregnant women should stay out of hot tubs, saunas and Jacuzzis?

True. These wonderfully relaxing activities can raise mom’s temperature to over 101 degrees Fahrenheit. The fetus has a temperature that is approximately 1 degree Celsius above that of the mom, and when mom’s temperature goes up too high, so does that of the fetus, to an even greater extent. Animal studies show that when the mother’s core temperature goes up, there is an increase in miscarriage and birth defects. So avoid hot tubs, Jacuzzis and saunas in early pregnancy. Also, exercise can cause a pregnant woman to become overheated (over 101 degrees Fahrenheit). So pregnant woman are advised not to exercise outside for long periods if it’s hot or humid. And when exercising, it’s important to drink plenty of fluids; dehydration raises body temperature. (A good rule to follow: Drink one glass of water every 20 minutes during a workout.)

And remember, (especially now that it’s summer), prolonged sunbathing can raise body temperature. It’s therefore important that pregnant women stay in the shade and keep cool when outdoors.

What about getting an X-ray?  Shouldn’t X-rays be avoided by pregnant women?

True. But according to the American College of Radiology, no single diagnostic X-ray results in radiation exposure to a degree that threatens a developing embryo or fetus; so if a single test is needed for health, it’s okay. But multiple X-rays or any X-rays that are less than essential should be postponed until after delivery.

What about video display terminals?  Is it all right for a pregnant woman to sit in front of a computer, especially for prolonged periods of time?

Yes. So far there is no scientific evidence that a pregnant woman needs to limit her time in front of a computer screen. Video display terminals (VDTs) don’t emit any form of dangerous radiation from the front, but do emit low-frequency electromagnetic radiation from the back of the device. The effect of the latter on pregnancy is not known. However, because ligaments are loosened and there is more fluid retention in pregnancy, prolonged use of the keyboard and incorrect positioning are more likely to cause carpal tunnel syndrome in pregnant women.

Hair dyes?  You shouldn’t dye or perm your hair in pregnancy?

False. There is no direct evidence that either will cause mutations, but I present this permission “to keep roots and highlights in good condition” with the caveat that there is very little medical data on this hair color or styling issue. One study did show that cosmetologists had a higher rate of miscarriage, so if a pregnant woman is a hairdresser and chronically exposed to chemicals, she should wear gloves and perhaps reduce this part of her job during the first trimester.

Painting —  don’t use lead paint while pregnant.

True. Inorganic pigments may contain not just lead but also chromium, cadmium, cobalt, nickel and mercury. Lead is of chief concern because it easily crosses the placenta, and a high level in pregnant women is associated with an increased risk of miscarriage, decreased infant IQ and stillbirth. So if you paint pictures or walls, check labels and avoid paints that contain lead.

Air travel.  Don’t fly in your first trimester.  Radiation from high-altitude flying can hurt your baby.

False. Air travel will not cause miscarriage. The only concern is that if you are going to miscarry because your pregnancy is abnormal, you don’t want to start bleeding at 30,000 feet or far from your physician’s care. (I generally check a patient in early pregnancy with ultrasound to ensure viability before she travels out of town.)  Nor do you want to go into labor while traveling. So most women should stop flying after 36 weeks’ gestation.

There is more radiation at high altitudes, but the amount in a single round-trip cross-country flight is well below safe upper limits. Radiation, however, is cumulative, and pregnant women who are frequent fliers or work in flight airplanes should keep track of their exposure. This can be done by going onto the FAA radiation estimation software. 

Pregnancy is an amazing time when a woman’s body goes through many changes. Although there are some definite “no-no’s,” many of our normal activities can be continued, especially if we follow the dictum “with moderation.”

Dr. Judith Reichman, the TODAY show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," which is now available in paperback. It is published by William Morrow, a division of HarperCollins.

PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.