Flying and travel when pregnant in the UK: cut-offs and letters

Three numbers, and only one of them is medical

Pregnant travel questions in the UK come down to three numbers: 28 weeks, when an airline may start asking for a letter; 32 weeks, the point at which a twin pregnancy is usually cut off; and 37 weeks, the usual single-pregnancy cut-off. Only the underlying obstetric reasoning is fixed. The cut-offs themselves are commercial policy set by each carrier, and they differ.

What NHS guidance says

The NHS position is that flying is not harmful to you or your baby, but that you should discuss any health issues or pregnancy complications with your midwife or doctor before you fly. The chance of going into labour is naturally higher after 37 weeks, or around 32 weeks if you are carrying twins, and some airlines will not let you fly towards the end of pregnancy.

The NHS also notes that many women prefer not to travel in the first 12 weeks because of nausea and tiredness, and that the risk of miscarriage is higher in the first three months whether you travel or not. Mid-pregnancy, roughly between four and six months, is when most people find travel easiest.

The letter, and why to ask early

After week 28 of pregnancy the airline may ask for a letter from your doctor or midwife confirming your due date and that you are not at risk of complications. The NHS warns of two practical things people do not expect: you may have to pay for the letter, and you may wait several weeks before you get it.

The Royal College of Obstetricians and Gynaecologists sets out the same requirement, adding that the letter should state when your baby is due and confirm that you are in good health with an uncomplicated pregnancy. Ask for it at least a month before you travel, and check what date the airline requires it to be issued within, because some will not accept a letter written more than a set number of days before departure.

What the RCOG advises on cut-offs

The RCOG's patient information is that flying is generally considered safe before 37 weeks if you are carrying one baby, and before 32 weeks with an uncomplicated twin pregnancy. From 37 weeks you could go into labour at any time, which is why many women choose not to fly after that point. Most airlines do not allow women to fly after 37 weeks, and the RCOG's advice is to check with your airline before flying.

That last point is the operative one. Do not book on the basis of a number you read on a guidance page. Read the specific carrier's expectant mothers policy for the exact flight you are taking, because short-haul and long-haul cut-offs can differ within the same airline, and codeshare flights may be governed by the operating carrier's rules rather than the one you booked with.

Blood clots on long flights

Long-distance travel of more than four hours carries a small risk of deep vein thrombosis, and pregnancy raises that risk. The NHS advice is to drink plenty of water and move about regularly, roughly every 30 minutes, and notes that graduated compression or support stockings bought from a pharmacy help reduce leg swelling.

The RCOG goes further for people with additional risk factors, who may be advised to have heparin injections regardless of the flight length: one on the day of the flight and daily for a few days afterwards. If you are prescribed these, you will need a letter from your doctor to carry the injections through security.

Ferries and cruises

Ferry companies set their own restrictions and may refuse to carry heavily pregnant women, often beyond 32 weeks on standard crossings and 28 weeks on high-speed crossings. Check before booking. For longer trips such as cruises, find out whether there are onboard facilities that can deal with a pregnancy problem and what medical services exist at the ports you call at.

The insurance clause that catches people

This is where a pregnant traveller is most exposed financially. Many standard travel policies limit or exclude pregnancy-related claims after a set gestation, sometimes earlier than the airline's own cut-off, and many exclude the cost of caring for a baby born abroad entirely. A premature birth overseas can generate a neonatal intensive care bill that dwarfs the holiday.

Read the policy wording rather than the summary. Check the gestation limit for cover, whether the newborn is covered if born on the trip, and whether the policy covers repatriation for both of you. Declare the pregnancy and any complications. And check the destination's entry requirements and health advice through official Foreign, Commonwealth and Development Office travel advice before you book, since some countries have entry restrictions for visibly pregnant travellers and some have health risks that are specifically serious in pregnancy.

Practical things that make the trip better

Book an aisle seat so getting up every half hour does not require negotiating with strangers. Keep your maternity notes with you rather than in the hold, because a doctor abroad will want them. Take your own snacks and a refillable water bottle. Wear the compression stockings for the whole journey, not just the flight. And find out before you go where the nearest maternity unit to your accommodation is.

What to do, and in what order

Check the specific airline's policy for your exact flight and gestation before booking anything. Ask your midwife or GP for the fit-to-fly letter at least a month ahead, and ask what it will cost. Buy travel insurance that explicitly covers pregnancy at your gestation and covers a newborn. Read the FCDO advice for the destination. Then plan the DVT precautions and pack your notes.