Pregnancy and Altitude

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Pregnancy and Altitude
Created On: Apr 18, 2007
Last Edited On: Apr 19, 2007

Pregnancy and Altitude

This fact sheet is to give information about altitude and it's effect on pregnancy. I have attempted to gather some articles and information here. As usual, a work in progress with more to come.

Web Links

This web page on Altitude and pregnancy looks like it had some good information.

Check out the Trekking while pregnant page from the Travel Medicine Center of Kathmandu

This article from the Journal of Public Health gives some research information
The Effect of High Altitude and Other Risk Factors on Birthweight

This page from Dr. has some basic information with other links.

Altitude and pregnancy from Wilderness Medicine, 4th Edition, Auerbach, 2001

"In high-altitude natives, pregnancy-induced hypertension is four times more common than in low-altitude pregnancies, preeclampsia is more common, and full-term infants are small for gestational age. These problems raise the issue of whether short-term altitude exposure may also pose a risk. So far, there is no evidence that these problems, or others such as spontaneous abortion, abruptio placentae, or placenta previa, can result from a sojourn to high altitude. Unfortunately, however, few data exist on the influence of a high-altitude visit during pregnancy on the mother and the fetus. For moderate altitude, the research to date has been reassuring. Artal et al studied seven sedentary women at 34 weeks gestation. Maximal and submaximal exercise tests were completed at sea level and 6000 feet (1829 m) after 2 to 4 days of acclimatization. They reported the expected decrease in maximal aerobic work but found no difference from sea level in fetal heart rate responses, or in maternal lactate, epinephrine, and norepinephrine levels. In a small number of subjects, the authors considered it safe for women in their third trimester of pregnancy to engage in brief bouts of exercise at moderate altitude. A similar conclusion was reached in a study of 12 pregnant subjects who exercised after ascent to 2225 m (7300 feet). The authors found no abnormal fetal heart rate responses and considered the exercise at altitude benign for both mother and fetus.29 Huch143 also concluded that short-term exposure, with exercise, was safe during pregnancy. In summary, the available data, though limited, indicate that short-term exposure to altitudes up to 2500 m (8202 feet), with exercise, is safe for a lowland woman with a normal pregnancy.

Another avenue of research has been alteration of blood gases during pregnancy. Human and animal studies with acute hypoxic challenge, as well as oxygen-breathing studies, have drawn two conclusions: (1) that a compromised placental-fetal circulation could be unmasked at high altitude, and (2) that a fetus with a normal placental-fetal circulation seems to tolerate a level of acute hypoxia far exceeding a moderate altitude exposure.

Based on the available research, it seems prudent to recommend that only women with normal, low-risk pregnancy undertake a sojourn to altitude. For these women, exposure to an altitude at which Sao2 will remain above 85% most of the time (up to 3000 m [9843 feet] altitude) appears to pose no risk of harm, but further study is needed to place these recommendations on a more solid scientific footing. An ultrasound or other assessment may be useful to rule out the more common complications before travel. Of course, it is not the altitude per se that determines whether the fetus becomes stressed but rather the maternal (and fetal) arterial oxygen transport. A woman with HAPE at 2500 m (8202 feet), for example, is much more hypoxemic than a healthy woman at 5000 m (16,404 feet). Therefore a strategy for preventing altitude illness, especially pulmonary edema, must be explained and implemented. Similarly, carboxyhemoglobin from smoking, lung disease, and other problems of oxygen transport will render the pregnant patient at altitude more hypoxemic and physiologically at a higher altitude. Consideration of a high-altitude sojourn in the developing world, or in a wilderness setting, raises other issues that may be more important than the modest hypoxia. These include remoteness from medical care should a problem arise, the quality of available medical care, the use of medications for such important things as malaria and traveler’s diarrhea (many of which are contraindicated in pregnancy), and the risks of trauma. "

Pregnancy and Altitude

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