Debunking myths about pregnancy hazards

Dr. Judith Reichman TODAY contributor • Profile • E-mail

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.

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