**6.1 General effects of travel in pregnant women's health**

The association between air travel and pregnancy outcome concerning early or late pregnancy loss, incidence of malformations placenta abruption, etc. is very limited. The average altitude for commercial long-haul flights is 10,000–12,500 m. The air pressure drops from 760 mmHg (at sea level) to 560 mmHg at flight level. This drop-in air pressure is largely compensated for by the cabin pressure in the aircraft (equivalence to an altitude of 1524–2438 m above sea level) so that an altitude of about 12,200 m is tolerated by the passengers without hypoxic stress. The partial pressure of oxygen in the arterial blood depends on the lung function (cave: chronic obstructive pulmonary diseases); in healthy passengers it drops from 95 mmHg to 53–78 mmHg in the airplane, and the arterial oxygen saturation decreases from 97 to 99% to 90–94% [36–41].

For healthy pregnant women who have sufficient oxygen saturation, this "relative" hypoxia in the plane poses no significant risk even for a healthy fetus. No influence on the fetal heart rate during short-haul flights was observed [30, 31, 42]. Due to the approximately 50% higher hemoglobin concentration compared to the

mother, the 20–30% higher oxygen affinity of fetal hemoglobin and the Bohr effect which guarantees a preferred oxygen release on the placental level, and negative effects on the fetuses are not to be feared. There is no need to fear mild hypoxia associated with air travel. However, this does not apply to pregnant women with reduced oxygen saturation due to underlying diseases (e.g., severe anemia, chronic obstructive pulmonary diseases) [41–48].

In general, a general attest must be introduced for the transportation of all pregnant passengers from the child's extrauterine viability, i.e., from the 25th week of pregnancy. The certificate should be issued in the period from approximately 1 week to 2 days before departure in order to guarantee that it is up to date to some extent. In addition to the exact gestational age, risks must also be specified which should be related to the health risk for both the mother and the child, and a distinction between single and multiple pregnancies should be documented. Concerning multiple pregnancies, long-haul flights up to the 28th week of pregnancy or short-haul flights up to the 32nd week of pregnancy in these cases are recommended to prevent premature birth. Short-haul flights are those routes on which an airport can be reached within 1 hour. Considering the average duration of pregnancy and birth in the case of single pregnancies, transport on long-haul flights up to the 36th week of pregnancy and on short-haul flights up to the 37th week of pregnancy is possible [41–48].

#### **6.2 People's health problems and thrombosis**

For all traveling people, the risk of VTE is slightly increased. It is significantly increased in passengers who have particular risk factors such as advanced age, taking estrogen-containing oral contraceptives or are at hormonal replacement therapy, obesity, and the presence of factor V Leiden mutation, at most high or very low body height [49–52].

The underlying mechanism responsible for travel-related thrombosis is not fully understood. But the fact that risk has been found for all modes of travel suggests that immobility and associated venous stasis may be a key factor in generating the disease. The reduction of oxygen levels may be an additional reason for the initiation of thrombus formation during long air travel in groups of people with specific risk factors.

Additional abovementioned thrombogenic risk factors increase the risk of VTE significantly.

Low air pressure and reduced blood oxygenation increase the risk of deep vein thrombosis in susceptible air passengers.

To date, deep vein thrombosis in air passengers has been mainly associated with the fact that they have been stationary for long periods of time as is usually the case in air travel.

Deep vein thrombosis occurs in the lower limbs when there are long periods of inactivity or sedentary activity.

The risk is that the clot can move through the bloodstream to the heart, lungs, and brain. This can happen hours, days, or weeks later after the initial formation of thrombosis. It is the cause of a heart attack or stroke.

Studies have shown that the risk of deep vein thrombosis of the lower limbs increases by two to four times after an air trip [49–52].

They believe that the main culprit is the hypoxia of blood resulting from low cabin pressure and reduced oxygen levels of passengers compared to what is happening on the ground. The decrease in oxygen concentration in the blood seems to activate the coagulation system leading to the formation of clots.

In addition, this research provides us with important information about who is at greater risk than others.

**161**

*Vein Thrombosis Risk in Women and Travel DOI: http://dx.doi.org/10.5772/intechopen.92229*

thrombosis and its consequences.

condition which can cause death.

and advice.

remain seated.

described.

is higher.

of long-haul passengers.

surgery, and some groups of cancer patients.

**6.3 Air travel, pulmonary embolism, and thrombosis**

thrombosis and thus be at greater risk than air travel.

their legs and remain motionless for many hours.

landings may be due to a pulmonary embolism.

constitute a very small percentage of those occurring.

**6.4 Precaution that must be taken into account during traveling**

Avoid drinking alcohol and excessive caffeine intake.

move their lower limbs. It is also not good to cross legs.

physicians prior to an air trip [5, 52–54].

increased risk for thrombosis.

These include people carrying the Leiden-type factor V mutant of the blood coagulation system, women taking birth control pills, patients recently undergoing

High-risk patients may be prescribed anticoagulant medicines such as aspirin, heparin, dipyridamole, clopidogrel (Plavix®), and others after medical evaluation

In addition, alcohol should be avoided in the flight, and passengers should be able to stretch their legs and do as much exercise and walking as possible. They can also wear special socks. These measures improve blood circulation and help prevent

Air travel can cause clots of the deep veins of the thigh and feet [49–52].

This thrombosis can in turn cause a pulmonary embolism which is a very serious

Thrombosis in the lower limbs (thighs, ankles, legs) is due to thickening phenomena that occur in the deep long veins due to the many hours that passengers

Lack of physical movement, dehydration observed in passengers, and alcohol consumption in flight are considered to be among the factors contributing to the occurrence of dangerous thrombotic conditions and pulmonary embolism.

In addition, some people may have inherited diseases with an increased risk of

Research shows that clotting problems occur in the lower limbs and in up to 10%

In fact, this syndrome is called by some people the "financial position" syndrome because passengers in these places do not have enough space in front of them to move

Researchers believe the incidence of pulmonary embolism after a long plane trip

The reason they are not detected is because the passengers are not immediately aware of what is happening or because the clinical signs are manifesting themselves severely a few hours after disembarkation. Even sudden deaths on flights or on

Some even argue that the problem is even greater and that the incidents detected

Passengers should drink plenty of water to eliminate the risk of dehydration.

Passengers should be able to get up, walk, do small exercises, or even stretch or

Patients with a personal or family history of thrombosis should consult their

Some researchers recommend that passengers wear special high-pressure socks to improve blood circulation to the lower limbs. This is especially true for people at

To date, 100 cases of pulmonary embolism due to venous thrombosis of the lower limbs have been described. A significant number of cases have died due to this condition. A case of lower limb amputation due to thrombosis has recently been

#### *Vein Thrombosis Risk in Women and Travel DOI: http://dx.doi.org/10.5772/intechopen.92229*

*Tourism*

obstructive pulmonary diseases) [41–48].

**6.2 People's health problems and thrombosis**

low body height [49–52].

significantly.

in air travel.

of people with specific risk factors.

thrombosis in susceptible air passengers.

thrombosis. It is the cause of a heart attack or stroke.

increases by two to four times after an air trip [49–52].

coagulation system leading to the formation of clots.

inactivity or sedentary activity.

at greater risk than others.

mother, the 20–30% higher oxygen affinity of fetal hemoglobin and the Bohr effect which guarantees a preferred oxygen release on the placental level, and negative effects on the fetuses are not to be feared. There is no need to fear mild hypoxia associated with air travel. However, this does not apply to pregnant women with reduced oxygen saturation due to underlying diseases (e.g., severe anemia, chronic

In general, a general attest must be introduced for the transportation of all pregnant passengers from the child's extrauterine viability, i.e., from the 25th week of pregnancy. The certificate should be issued in the period from approximately 1 week to 2 days before departure in order to guarantee that it is up to date to some extent. In addition to the exact gestational age, risks must also be specified which should be related to the health risk for both the mother and the child, and a distinction between single and multiple pregnancies should be documented. Concerning multiple pregnancies, long-haul flights up to the 28th week of pregnancy or short-haul flights up to the 32nd week of pregnancy in these cases are recommended to prevent premature birth. Short-haul flights are those routes on which an airport can be reached within 1 hour. Considering the average duration of pregnancy and birth in the case of single pregnancies, transport on long-haul flights up to the 36th week of pregnancy and on

short-haul flights up to the 37th week of pregnancy is possible [41–48].

For all traveling people, the risk of VTE is slightly increased. It is significantly increased in passengers who have particular risk factors such as advanced age, taking estrogen-containing oral contraceptives or are at hormonal replacement therapy, obesity, and the presence of factor V Leiden mutation, at most high or very

The underlying mechanism responsible for travel-related thrombosis is not fully understood. But the fact that risk has been found for all modes of travel suggests that immobility and associated venous stasis may be a key factor in generating the disease. The reduction of oxygen levels may be an additional reason for the initiation of thrombus formation during long air travel in groups

Additional abovementioned thrombogenic risk factors increase the risk of VTE

Low air pressure and reduced blood oxygenation increase the risk of deep vein

To date, deep vein thrombosis in air passengers has been mainly associated with the fact that they have been stationary for long periods of time as is usually the case

Deep vein thrombosis occurs in the lower limbs when there are long periods of

The risk is that the clot can move through the bloodstream to the heart, lungs, and brain. This can happen hours, days, or weeks later after the initial formation of

Studies have shown that the risk of deep vein thrombosis of the lower limbs

They believe that the main culprit is the hypoxia of blood resulting from low cabin pressure and reduced oxygen levels of passengers compared to what is happening on the ground. The decrease in oxygen concentration in the blood seems to activate the

In addition, this research provides us with important information about who is

**160**

These include people carrying the Leiden-type factor V mutant of the blood coagulation system, women taking birth control pills, patients recently undergoing surgery, and some groups of cancer patients.

High-risk patients may be prescribed anticoagulant medicines such as aspirin, heparin, dipyridamole, clopidogrel (Plavix®), and others after medical evaluation and advice.

In addition, alcohol should be avoided in the flight, and passengers should be able to stretch their legs and do as much exercise and walking as possible. They can also wear special socks. These measures improve blood circulation and help prevent thrombosis and its consequences.
