Altitude & Pregnancy
How does high altitude affect pregnancy?
High Altitude Resident Mothers
Infants born to women of high altitude residence have lower birth weights on average than those born to low altitude mothers. This is due to slower growth rate in the uterus during late pregnancy, after 33 weeks. With that being said, high altitude babies do not have negative health consequences and risks because of their lower weight, unlike low weight babies born to smoking mothers. Recent data in Colorado shows no increase in infant death rates of babies born at high altitude compared with those born at low altitude. Pregnancy-associated hypertension and preeclampsia are slightly more common in high altitude pregnancies.
Low Altitude Resident Mothers Visiting High Altitude
Many women in all stages of pregnancy safely visit moderate altitude every year. In fact, elevated hormone levels (progesterone) increase the breathing rate, raise blood oxygen and may protect against AMS.
The safety of travel to altitude during pregnancy has not been thoroughly studied. However, many pregnant tourists visit high altitude destinations such as Colorado every year and report no complications. One study found no difference in fetal heart changes and circulating stress hormones between mothers exercising at sea level and at 6000ft. This suggests that the exposure to this altitude does not produce additional stress on pregnant women. Women with complications of pregnancy, such as hypertension, preeclampsia, placental insufficiency, or any other complication, should avoid unnecessary exposure to high altitude. The pregnant woman can take Diamox, but only if truly necessary; slow ascent is preferred to medications.
Recommendations for pregnant tourists visiting high altitude:
Have a check-up with your doctor to assure your pregnancy is low-risk; this might include an ultrasound
Avoid trauma if skiing, cycling, climbing, etc.
Avoid over-exertion; exercise a bit less than at you do at home
Stay well hydrated
Avoid altitude illness; see above
Seek medical care early if any problems
Peter Hackett, MD and Linda Keyes, MD
INSTITUTE FOR ALTITUDE MEDICINE
Pregnancy and Travel to Altitude FAQ
Most pregnant women can safely travel to high altitude destinations during pregnancy without any complications or problems. Here are some commonly asked questions about travel to altitude during pregnancy.
How high can I go when I am pregnant?
Sleeping altitude is the important factor, not maximum altitude reached during the day. As long as your pregnancy is not considered "high-risk", travel to sleeping altitudes up to 9-10,000 ft in Colorado or elsewhere should not pose a risk to you or your fetus. Information on higher sleeping altitudes is too limited to provide quality guidelines.
What precautions should I take before travelling to altitude?
We recommend a check up by your obstetrician and an ultrasound to make sure the pregnancy is normal so far. If possible, spend a night at a medium altitude, between 5-7,000 ft before sleeping above 8500 ft to help your body adjust.
Identify how and where you will get medical care at your destination if any problems were to develop.
Who should not travel to high altitude during pregnancy?
Any woman with a highrisk pregnancy condition such as pregnancy-induced hypertension, preecclampsia or intrauterine growth retardation should not travel to high altitude. Ask your obstetrician if you are not sure if your pregnancy is high risk. Women with certain underlying medical problems are also at risk of complications and should probably avoid travel to high altitude. These diseases include certain congenital heart diseases, some restrictive lung diseases like sarcoidosis or pulmonary fibrosis, or significant anemia. Discuss with your doctor if you have any of these problems before going to high altitude while pregnant. Finally, women who smoke should not travel to high altitude while pregnant.
Will going to high altitude increase my risk of miscarriage or birth defects?
There is no risk of increased miscarriage or birth defects in lowland women traveling to high altitude.
What precautions should I take when I arrive at altitude?
Take it easy the first several days at altitude, and do not exert yourself at a level greater than you would do at sea-level (e.g. no major hike to the top of a big peak if that's not something you're used to doing). Avoid trauma and don't take unnecessary risks. If you ski, hike or climb, do so carefully and stay well within your abilities. Staying hydrated is important, as is taking some time to let your body adjust to the altitude before exerting yourself. Acetaminophen (brand name: Tylenol) is safe to take if you develop a headache.
Can I exercise at altitude while I am pregnant?
In general, exercise is safe and beneficial during pregnancy. We know that exercise up to 8000ft is safe for non-smoking women. At higher altitudes, take extra time to acclimatize before exercising and avoid heavy exertion or very strenuous exercise. Keep the exertion level lower than you would do at home and include more frequent rests.
Am I at increased risk of altitude sickness because I am pregnant?
Being pregnant will not increase your risk of developing altitude illness. In fact, the increased progesterone of pregnancy makes you breathe more at altitude. This keeps your oxygen level higher than non-pregnant women, and thus helps to prevent altitude sickness. We very rarely see pregnant women with altitude sickness.
Can I take medicine to prevent mountain sickness while pregnant?
Most pregnant women are naturally protected against altitude sickness due to the increased respiratory drive of pregnancy and preventive medications are not necessary. Acetazolamide (brand name: Diamox) is the best medicine for altitude sickness prevention, but this medicine is not recommended during pregnancy unless truly necessary. The safety and effectiveness of herbal medications like Ginkgo Biloba are unclear during pregnancy and are not recommended. It is OK to treat a headache with over-the-counter medicine like acetaminophen (brand name: Tylenol).
What if I live at high altitude and I'm pregnant?
Women who live at high altitude (>8000 ft) throughout their pregnancy may be at risk for certain pregnancy-related complications such as high blood pressure or preecclampsia. Babies born at high altitude tend to be smaller than their sea-level counterparts, but healthy. It is important that you receive ongoing pre-natal care and monitoring throughout your pregnancy. Your doctor can tell you if you are at risk, or are developing any problems.