03 Aug 2010

Air travel during pregnancy

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Travelling by air during pregnancy is a very important issue and one that generates many questions from pregnant women.

Travelling by air is very important during pregnancy because it is very hard to go to Port Douglas, Fiji or Noumea shortly after your baby (? babies) is (are) born.

The complication we wish to prevent is that of formation of blood clots in the veins of the legs (Deep Vein Thrombosis, or DVT) and movement of such clots to the lungs (Pulmonary Embolus, or PE). Because doctors love acronyms, we call DVTs and PEs VTE – Venous Thrombo-Embolism.

A word about clotting in pregnancy:

One of the many physiological changes that occurs during pregnancy is that your blood becomes hyper coagulable – or clots more readily – than when you are not pregnant. In plain English, your blood is thicker than when you are not pregnant. This is a very important adaptation in that it limits bleeding from the womb after your placenta (afterbirth) has detached from the wall of your womb once your baby has been born. The combination of contraction of the muscle fibres after the birth of the placenta and the relative thickness of the blood are the physiological mechanisms that prevent excessive bleeding after you have given birth.

However the downside of having thicker blood during pregnancy is that it is more likely to form blood clots within your blood vessels during (or up to six weeks after) your pregnancy. The fact that you have a big lump in your pelvis (your pregnancy) that can compress the veins of your pelvis does not help because such compression causes slowing of blood flow (stasis) in your leg veins, which can also lead to clot formation.

If that wasn’t enough to worry about, some pregnant women have particular predispositions towards clot formation that can increase their risk of clot formation. Pregnant women with an increased risk of clots during pregnancy can include those with:
A personal history of VTE
A family history of VTE
The following events affecting previous pregnancies:
Recurrent miscarriages (3 or more)
Severe preeclampsia
Poor growth of their baby
Unexplained stillbirths.
Of course most women who have suffered the above complications are not particularly at risk of clots, although some are. Those particularly at risk often have some form of subtle alteration in their clotting systems that make them at increased risk of both clots and the pregnancy complications listed above. These conditions can be familial. They include (long name warning!):
Antiphospholipid Syndrome
Inherited thrombophilia, including Factor V deficiency, Protein S and Protein C deficiency.
If you have a personal or family history of VTE, or have suffered any of the above pregnancy complications, I will arrange the necessary blood tests for these conditions.

So back to Air travel in Pregnancy:

Air travel is an independent risk factor for VTE because of the dehydration, lack of mobility and increased cabin pressure involved in modern flying.

Because of the rarity of blood clots even occurring during pregnancy, there is limited evidence upon which to base advice regarding prevention of VTE during pregnancy. The following advice represents my amalgam of the existing evidence and current recommendations by organisations such as the British, American, Australian and NZ Colleges of Obstetricians and Gynaecologists.

I would include women with multiple pregnancies as “high risk” in the lists below.

Ensure you are mobile (up and walking around) during your flight
Do leg stretching / mobility exercises
Drink plenty of water
Minimise your caffeine intake
No alcohol (sorry!)
Wear properly fitted anti embolism stockings (these can be purchased from any chemist)
You must seek medical assistance urgently if you experience any of the following symptoms during or after your flight:
i.Leg soreness, redness or swelling
ii.Shortness of breath or chest pain

2.LOW RISK WOMEN UNDER 20 – 24 WEEKS, SHORT HAUL (less than 7 hours):
Nothing further.

As in 1, above, plus:
Take low dose aspirin (100 mg, per day – Cartia) for 5 days before and after each flight.
In truth there is not good evidence that low dose aspirin prevents VTE but we know that it helps to prevent arterial (as opposed to venous) clots, it thins the blood a little, and is safe during pregnancy

4.HIGH RISK WOMEN (i.e. those with multiple pregnancy, previous clots, a family history of clots or antiphospholipid syndrome or a thrombophilia):
As in 1 and 2, above, plus:
Consider replacing aspirin with low dose heparin (blood thinning) injections. I will prescribe these and arrange for you to be taught how to use them).

You need to be accompanied by your Obstetrician to ensure your safety and that of your baby (Business class at least)
Your obstetrician is allowed to drink the free champagne during the flight.

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