Pregnancy and high altitude
Within their article, Hezelgrave and colleagues discuss the risks of
air travel to the fetus. They come to the conclusion that "the fetus is
able to maintain a higher oxygen saturation ...during routine flight
conditions", presumably in relation to the mother's saturation levels.
Although this is useful information, it neglects another situation in
which low oxygen levels play an important role in travel during pregnancy;
that of high altitude. It is important to be aware that the low partial
pressure of oxygen present when traveling at high altitude (as opposed to
during air travel) may pose additional risks to the fetus, and pregnant
patients should be made aware of these potential risks.
Although fetal pO2 can be preserved at altitude even when maternal
pO2 has dropped significantly, there is a substantial body of evidence
that residents at high altitudes suffer a higher level of many of the
complications of pregnancy (1). The evidence pertaining to short duration
visits to altitude is less clear cut. The available evidence supports the
idea that travel up to around 3,000m during a low-risk pregnancy in a non-
smoker is safe; but suggests that these patients may require a longer
period of acclimatization (2). At altitudes above this there is a
distinct lack of evidence regarding safety and patients need to be made
aware of this.
It is also important to consider that although pregnancy may confer
physiologic protection against acute mountain sickness it also limits the
options when considering prophylactic medication. Acetazolamide and
ginkgo biloba are both not recommended during pregnancy, which leaves
dexamethasone as a sole treatment option for treatment of acute mountain
sickness with no effective prophylactic option.
1) Keyes, L.E. (2010). Travel and exercise at high altitude during
pregnancy. Wilderness and Mountain Medicine. Wilderness Medical Society
Conference: Park City, Utah
2) Hackett, P.H. and Roach, R.C. High-altitude medicine. In Auerbach,
P.S. (Ed). (2001). Wilderness Medicine. (4th Ed). Mosby: St.Louis
Competing interests: No competing interests