Altitude and Pregnancy

Travel to some destinations includes the possibility of exposure to high altitudes.  For the most part, travel to moderate altitudes (5,000-12,000 feet; 1500-4000 meters) is considered harmless in pregnancy.  Some studies seem to indicate that prolonged stays at these altitudes may result in smaller babies, but other studies don’t show this finding.  In support of the idea of altitude being safe for babies is the fact that an unborn baby survives quite well on an oxygen level much less than that of the mother.

There are limits, though, and some conditions in which travel to altitude would be ill advised.  Remember that the higher you go the less oxygen there is in the air.  Even babies have their limits as to how little oxygen they can survive on, and a baby is dependent on the umbilical cord for its oxygen supply.  It can’t simply breathe deeper if the going gets tough.  Most experts would discourage travel above about 12,000 feet during pregnancy.

Also, a baby that is already low on oxygen will not tolerate altitude exposure as readily as an otherwise healthy one.  If you are anemic, for instance, your blood is already carrying less than the normal amount of oxygen.  Or if you are carrying twins or your baby has been diagnosed as having “intrauterine growth restriction” the oxygen supply is already reduced.  In these instances, you should be cautious about going to a place of high altitude.  (In some cases, this might even include some airplane flights.)

Our main concern with altitude travel and pregnancy, however, has to do with the fact that many people simply do not tolerate high altitude travel very well.  At altitudes of over about 10,000 feet they may develop “acute mountain sickness”.  This may be nothing more than simple insomnia and shortness of breath.  But it often progresses to include headache, nausea and vomiting.  In severe cases, fluid may collect in the lungs (pulmonary edema) or even the brain, causing severe difficulty in breathing as well as psychiatric symptoms and even coma.  In these severe cases, the only treatment is to promptly descend to a lower altitude.

As headache, insomnia, nausea and vomiting are common symptoms in pregnancy anyway, a little bit of altitude sickness can go a long way toward making you feel absolutely terrible.

A person’s body acclimatizes to the altitude over 2-3 days by changing the blood to a more alkaline state where it can normally carry more oxygen.  This is accomplished through the lungs and kidneys by getting rid of extra fluid and breathing more deeply.  Medically, we can often hasten this process by using a medicine called acetazolamide (DiamoxÒ), which one may begin taking a day or two before going to altitude.  This medicine is used in pregnancy for some other medical conditions and is generally thought safe.  There have been occasional reports, however, of newborn illnesses possibly associated with the drug.  For that reason, we prefer not to prescribe it during pregnancy.  We advise, instead, that you simply allow a day or two to let your body adjust before undertaking any strenuous activities at altitude.

In serious cases of altitude sickness, there are other medicines that are used for treatment.  These do not prevent the illness, however, and even when given, their use is combined with a prompt descent to a lower altitude.

There is one other substance that is often recommended for prevention of altitude sickness.  If you travel to the Andes, it is very likely you will be offered a cup of coca tea.  Be reassured that this is harmless.  The tea is made from boiling the coca leaves, a process quite different from that used for making cocaine.  Medical studies show no less altitude sickness, however, among those who drink the tea.  If it works at all, it is probably because it keeps you sitting and admiring the scenery rather than running up and down the mountains and using up all your oxygen.

A couple of warnings about coca tea, though.  If for some reason you undergo a drug test a few days after sipping the tea, you will test positive for cocaine.  And it is just as illegal to transport the coca tea leaves as to import cocaine itself.

One other consideration regarding altitude is that the majority of high altitude activities occur in remote areas, a long way from any available medical care.  Obstetrical emergencies tend to be sudden and dramatic.  If your are going to go to remote areas when you are pregnant, therefore, you should first make sure that your pregnancy is healthy and you should have arrangements made for transportation to medical care if an emergency occurs.