A common question asked of midwives and doctors by pregnant women is whether flying during pregnancy is safe. For pregnant women, concerns usually centre around the possible effects of flight on the health and well being of their unborn baby, the possibility that the flight may cause preterm labour, and fears of what would happen if an obstetric emergency did occur in flight.

The good news is that there is no conclusive research which suggests there is a risk of adverse pregnancy outcomes, such as preterm labour, preterm rupture of the membranes or abruption, due to flying during pregnancy. As seasoned flyers will know though, the physiological and environmental changes associated with commercial air travel can have negative effects on the body, some just causing discomfort and others of greater concern.

Preterm labour

It is important to remember that while some women may experience the first signs of pre-term labour or miscarriage in flight, no evidence suggests that one is connected to the other. Just as women may experience these events anywhere and at anytime on land, so too some may be in transit on any form of land, sea or air travel when symptoms occur. Be guided by the advice of your midwife or doctor in regards to whether flying during pregnancy is recommended for you.

That said, while there is no evidence to suggest a link between air travel and preterm labour, there is also no way to prevent labour from beginning while you are in the air! To minimise this risk, airlines place restrictions on how many weeks pregnant passengers can be and still be admitted to a flight. Each airline has its own restrictions which take account of how many weeks pregnant you will be when flying, how many babies you are carrying, and the length of the flight.

Many airlines require a letter from your doctor or midwife if you fly beyond 28 weeks of pregnancy. It is important to ensure you are aware of your chosen airline’s flight restrictions before making plans to fly, and to declare your pregnancy when booking your flights. This enables the airline to best ensure your safety.

Reduced mobility

Unless you are lucky enough to be travelling in first or business class, air travel can result in a significant reduction in mobility. The most concerning effect of reduced mobility is the possibility of deep vein thrombosis (DVT). DVT is the formation of a blood clot (thrombus) in a deep vein, usually in the legs. If the clot detaches and begins travelling through the body, the effect is potentially life threatening.

The risk of DVT is increased by a reduction in circulation to the legs, which for pregnant women is exacerbated by long periods spent sitting without room to stretch and move. Coupled with the physiological changes in coagulation (blood clotting) in pregnancy the risk of DVT may be accentuated by risk factors such as previous DVT or obesity.

DVT is a factor that certainly should be considered when flying during pregnancy, especially for medium- to long-haul journeys (greater than 4 hours) and/or where these risk factors are present. Your doctor or midwife may recommend the use of pressure stockings for medium- to long-haul journeys, which have the effect of improving circulation in the legs. The use of low molecular weight Heparin (a blood thinner marketed in Australia as Clexaine) may be recommended on the day of travel and for a few days after where increased risk factors for DVT exist.

Other ways you can naturally reduce the risk of DVT are:

• Select an aisle seat so you can stretch and get up more easily
• Keep your fluids up while avoiding caffeinated and alcoholic drinks which increase dehydration
• Walk around the cabin regularly if possible, especially on long-haul flights
• Perform some simple in-seat exercises to increase circulation – your doctor or midwife can show you these

Reduced Barometric Pressure

The first effect on the body many people notice in flight is a change in barometric pressure. You detect it with your ears, inducing you to try to change your ear pressure or make you ears ‘pop.’ Reduced barometric pressure can more commonly cause ear pain in pregnant women due to the vasodilatation (increased dilation of blood vessels) which occurs in pregnancy.

Where the cabin not pressurised, at between 4000 and 8000 feet we would find it difficult to breath as a result of lowered barometric pressure. However even though plane cabins are pressurised, reduced barometric pressure reduces the oxygen saturation in your blood. The good news is that because your baby has a higher red blood cell count and favourable haemoglobin properties, there is considered to be little if any change in your baby’s oxygen pressures during flight, making flying during pregnancy safe in this regard.

Low Humidity

The air in an plane cabin is quite dry due to its low humidity (moisture levels) of about 15%. While this can increase fluid loss and dry out mucous membranes, the loss is insufficient to cause dehydration. Remaining well hydrated when flying during pregnancy, easily combats this effect of flight.

Radiation

Because when we fly the plane rises above both clouds and the bulk of atmospheric pollution (smog) we are all at greater risk of exposure to solar/cosmic radiation. Because the effect of radiation is cumulative, the more you fly the greater the risk to your baby. As a result pregnant flight attendants often have restrictions placed upon them in regards to how many flights they can complete while pregnant and in some cases may be grounded altogether. However while studies vary on determining how much is too much, all refer to total travel time in excess of 160 hours during pregnancy! Unless you travel constantly, radiation is unlikely to affect the safety of flying during pregnancy for most women.

Body scanners, both in the form of security arches and handheld ion scanners used by airport staff, utilise ionising radiation. Studies have equated the amount of radiation absorbed by the human body during routine scanning as equivalent to two minutes flying at cruising altitude or one hour spent at ground level – that’s less than your mobile phone. This dose is not considered dangerous during pregnancy and there is no information to suggest the need to avoid security scans when pregnant.

General Considerations

If you tend to suffer from motion sickness, flying during pregnancy may exacerbate morning sickness. While air sickness may not deter you from flying you might wish to consider taking along supplies to combat this, such as sea-sickness bands, ginger tablets or chews, and some dry crackers if you find these helpful.

If you take out travel insurance, ensure it covers obstetric complications. While you may not use it, it can be an important thing to have in place should an obstetric issue occur either in flight or while at your travel destination.

If you are in the early weeks of pregnancy, and particularly if you have experienced miscarriage or ectopic pregnancy, it may be prudent to have an ultrasound scan prior to your flight. This will enable determination of the viability of your pregnancy and the baby’s position (to rule out ectopic pregnancy).

Having an ultrasound has no impact on the risk or lack thereof of flying during pregnancy. However in the case of an ectopic pregnancy it can help to avoid a medical emergency far from home. In the case of recurrent miscarriage it may help to provide peace of mind by identifying a non-viable pregnancy (such as a blighted ovum) prior to travel.