Women often ask if travelling in pregnancy is safe? Most women who are pregnant are well, considered 'low risk' and it is perfectly safe for them to ﬂy. Some women will have medical problems that make it unsafe but this is unusual.
Medical concerns are either risks associated with the travel itself or risks associated with the destination.
What are the travel guidelines?
Many airlines place restrictions on travel in advanced pregnancy but these are not consistent and vary from one airline to another.
Typical guidelines are:
- Unlimited travel to 28 weeks
- Doctors letter required after 28 weeks
- Twin pregnancies, no ﬂying after 32 completed weeks of pregnancy.
- Singleton pregnancies, no ﬂying after 36 completed weeks of pregnancy.
Our advice is to check with the airline.
What are the risks at different gestations?
In the ﬁrst trimester, up to 12 weeks, there is an increased risk of miscarriage and ectopic pregnancy. This risk is probably not increased by ﬂying. One study of pregnant ﬂight attendants has shown that the risk of miscarriage may be slightly increased by airline travel, but the data in this study is difﬁcult to interpret and the increase risk is small. If a miscarriage or an ectopic does occur in the destination country then it may be difﬁcult to access high quality medical care or the cost of the medical care may be high.
The second trimester is the best time to travel. The pregnancy is usually well established, most women feel ﬁt and well, the risk of preterm delivery is small and few medical check ups are needed during this period.
Travel in the third trimester is a little more difﬁcult, ﬁrstly the pregnancy is bigger making ﬂying more uncomfortable, there is an increase in the risk of deep vein thrombosis and a small chance of premature birth. The risk of premature delivery is around one in ten pregnancies and women are at increased risk if they have had a previous preterm delivery, recurrent episodes of threatened preterm labour, a multiple pregnancy or a history of cervical trauma.
What are the speciﬁc risks of airline travel?
Risks are related to low oxygen saturation, exposure to radiation, venous thromboembolism (DVT) and miscarriage and preterm birth.
Low oxygen saturation
In commercial aircraft the oxygen in the air supply is lower that that at sea level. The difference is not large but women may experience an increased heart rate, a slight increase in blood pressure and slight shortness of breath. The amount of oxygen in the blood stream also goes down slightly but this does not affect the baby. The reason for this is that the blood in the baby has a higher afﬁnity for oxygen than the maternal blood so the baby is able to maintain oxygen saturation.
Exposure to cosmic radiation (gamma rays) at 35,000 feet is greater than at sea level. The additional amount of radiation exposure is small. For a transatlantic ﬂight the exposure is around 0.05 mSv which compares to 0.1mSv for a standard chest x-ray. In other words ﬂying to The States and back is similar to having a chest x-ray! This sounds alarming but needs to be put in context: current opinion suggests that exposure to radiation above 50mSv is needed to cause an increase risk of fetal malformation or miscarriage. Flying is therefore very safe and it is only frequent ﬂiers and airline staff who need to be cautious.
Venous thrombosis-embolism (DVT)
DVT is 10 times more common in pregnant women than matched controls. Prolonged periods of immobility, dehydration and reduced oxygen in the blood further increase the risk. As a result the risk associated with airline travel is two to four times higher even for non pregnant people.
There are a number of steps that can be taken to reduce this risk:
- Take 75mg Aspirin before the ﬂight (it thins the blood slightly).
- Wear elastic stockings during the ﬂight.
- Drink plenty of liquid throughout the ﬂight.
- Mobilise regularly and do exercises during the ﬂight (an aisle seat helps with this).
Miscarriage and preterm birth
As mentioned previously there may be a very small increased risk of miscarriage caused by ﬂying a lot, but there does not seem to be an increased risk of preterm birth. The message here is that ﬂying is not dangerous in this respect.
Indications for caution before travel
Some women who are pregnant need to be careful about travelling because of a previous medical condition which may increase the risk to them or their baby.
The following list is not exhaustive but gives some idea of the relevant conditions.
- Recent amniocentesis
- Severe anaemia or heamoglobinopathy
- Multiple pregnancy
- History of cardiac disease
- Intrauterine growth restriction
- Placenta praevia
- Previous pre-term delivery
- High risk of thrombosis
All of these increase the risk of ﬂying and may be a contraindication to airline travel whilst pregnant.
Travelling to exotic locations
More of us are now opting to ﬂy to exotic locations in the search of winter sunshine or because of work, but of course when making plans there are additional considerations for pregnant women.
There are concerns regarding vaccination, tropical diseases such as Zika virus, malaria and travellers diarrhoea.
Vaccinations in pregnancy
The risk of vaccinations in pregnancy on the development of the baby is unclear. Most sources agree that there is no evidence of risk from vaccination of pregnant women with inactivated virus, bacterial vaccines or toxoids.
Yellow fever is live vaccine and should be avoided (a doctors letter may be required). Typhoid vaccination may cause a febrile reaction and is best avoided unless the risk is considered high.
The disease prevalence of some diseases such as Rubella is much higher in developing countries and the vaccine cannot be given in pregnancy. Women who are not immune should avoid these areas. Primary HIV infection in pregnancy also carries a greater risk of transmission to the baby. Other diseases such as Dengue fever and Hepatitis E are more dangerous in pregnancy and there are no vaccines. Food hygiene may also not be so high so there will also be a greater prevalence of Lysteriosis, Typhoid and Toxoplasmosis.
Advice on Zika is complex. It is best describe in a recent update by the RCOG the URL link for which is provided below. https://www.rcog.org.uk/globalassets/documents/news/zika-virus-rcogv21-22-11-2016_st_updateﬁnal.pdf
Malaria in pregnancy carries a substantial risk to the mother and baby, especially infection with Plasmodium falciparum. Malaria prophylaxis carries a low risk to the baby compared with the substantial risks to the pregancy if malaria is contracted. It is essential that women sleep under treated mosquito nets and wear long trousers and long sleeved tops after dark.
On balance it is probably best to avoid areas where there is a high risk of malaria as the disease may be particularly severe in pregnancy and the drugs that can be used all carry a potential risk for the baby.
It is difﬁcult to avoid getting travellers diarrhoea and it affects up to half of visitors to tropical and sub-tropical destinations. The best advice is to be meticulous in hand washing, to drink only unopened bottled water and to not eat uncooked food. Despite these precautions it is difﬁcult to avoid.
In most simple cases the main problems are fever and dehydration which may lead to ketosis and an increased risk of premature birth. Fever can be controlled by oral Paracetamol which is safe to take during pregnancy. Rehydration with sugary oral ﬂuids such as 'Flat Coke' is very effective though sometimes intravenous ﬂuids may be required.
Not all cases are 'simple' and sometimes oral antibiotics are required (not all of these are safe in pregnancy).
Most women are safe to travel in pregnancy, most of the risk lies not in the travel itself but in the risks associated with the destination. It is always best to consult with a doctor when making plans to visit tropical and sub-tropical destinations during pregnancy.