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Pregnancy and Altitude
Q. I just found out I'm pregnant; should I be concerned about altitude travel?
A. Yes, but primarily in the sense of evaluating all potential risks and making your best personal decision, as you would with any other climbing variables. The ACOG (American College of Obstetrics and Gynecology) suggests that pregnant women new to exercise keep their exercising heart rate under 140 bpm (beats per minute); those who were avid exercisers prior to becoming pregnant should stay below 160 bpm (1). A woman who is pregnant is also advised to modify the duration of exercise, pay very close attention to how she feels and how the baby is responding to exertion, stay well hydrated, and avoid hyperthermia.
Due to the body’s natural tendency to work harder at higher altitude (including higher heart rates), the factors that most affect whether a woman will feel comfortable at altitude include rate of ascent, exercise pace, terrain, and how far along the woman is. In general, past the first trimester (when risk of ectopic pregnancy or miscarriage is highest) and before the 3rd trimester (when risk of early pregnancy and complications could occur) (2) if the pregnant woman is feeling good, short stays at altitude should not have significant impact on the fetus or on the woman’s health. When in doubt, however, consult your physician. Also consider where you will be staying at altitude; a woman planning to stay near Boulder, Colorado will have a different response to potential risks than one visiting family in the Swiss Alps or another who had originally planned to trek in Nepal, far away from her medical advisors, should anything go wrong mid-pregnancy.
According to both the Center for Disease Control and David Shlim (1997) at http://www.ciwec-clinic.com/ , “there are no reported cases of high altitude exerting a negative outcome on pregnancy in a trekker or climber. Oxygen saturation is fairly well maintained up to an altitude of 10,000-12,000 feet…Because of the rapid drop-off in oxygenation above 12,000 feet (3,658 m) or so, we generally recommend that pregnant women avoid exposures above that height. However, there are numerous anecdotal stories of women who have traveled higher while pregnant and who gave birth to normal children. “
Another invaluable source of information for pregnant women considering trekking to altitude is provided at: http://www.ciwec-clinic.com by the CIWEC Clinic Travel Medicine Center.
A summary of findings at that site include:
“Acclimatization to altitude can occur during pregnancy; it is not possible to predict how well an individual, pregnant or not, will respond to altitude. Most pregnancies show good exercise tolerance at altitude, but problems such as bleeding and pre-term labor have been noted to be the most common complications of pregnancy at altitude. The risk of one of these complications has been shown to increase with strenuous exercise, dehydration and rapid ascent without acclimatization. Exercise without full acclimatization (as can occur during a trek) has also been shown to impair fetal oxygenation.” (2)
On exposure to altitude:
“Long term exposure to altitude while pregnant has been shown to retard fetal growth and it has been acknowledged that women tend to give birth to small babies if they spend much of their pregnancy at altitude. Small babies have their own set of problems at birth such as hypothermia, low blood sugar and a higher rate of breathing problems and a need for intervention. This is more a problem of longer-term exposure to altitude and it is difficult to predict the effect of a short visit to altitude when pregnant. It seems probable that a two-week visit to moderate altitude (less than 3,000 meters) is unlikely to affect the final birth weight of a baby.” (2)
On postponing a trekking trip:
“The following are situations where pregnant women would be wise to consider postponing a trekking trip to Nepal:
If you do decide to stay somewhere at higher altitude, make sure your ascent is slow and that you acclimatize well. An unacclimatized pregnant woman should avoid intense exercise during the first 3-4 days after gaining altitude (>6500’) and only participate in sports such as hiking, mountain climbing, or skiing if they are already trained in such altitude (>8000’) sports (1). It’s likely to be fairly easy to confuse the nausea associated with “morning sickness” with the nausea you might experience with early signs of AMS. Be sure to build in plenty of rest days, watch your footing carefully to avoid falling, keep well hydrated, and descend if you feel worse.
(1) Kulpa, Patty, MD. “Exercise During Pregnancy and Post Partum”, p. 191-199 in Medical and Orthopedic Issues of Active and Athletic Women, Agostini, Rosemary, MD (1994) Hanley & Belfus, Inc: Philadelphia.
(2) CIWEC Clinic Travel Medicine Center: http://www.ciwec-clinic.com
See also Climbing, Exercise and Pregnancy: A Reality Check www.bodyresults.com/e2pregnancyexercise.asp