How to use this tool
Choose whether you know your due date or the first day of your last period, then enter that date.
Enter your outbound flight date and, if you have one, your return date.
Pick single pregnancy or multiple pregnancy (twins or more).
Choose the airline for each flight. If you fly out and back with different airlines, set each one.
Read the result for each flight: your weeks and days, whether a letter is mentioned, and how close you are to the airline's limit.
Open the airline's own page from the result and confirm the rule before you book or fly.
When do you need a fit to fly letter in pregnancy?
Many airlines ask for a letter or form once you are past about 28 weeks. Before that, the airlines we checked do not ask for one for an uncomplicated pregnancy.
The NHS says that after week 28 an airline may ask for a letter from your doctor or midwife. That letter confirms your due date and that you are not at risk of complications.
The RCOG patient leaflet says the same thing in other words. It says the letter should confirm when your baby is due and that you are healthy with an uncomplicated pregnancy.
Airlines differ on whether the letter is required, recommended or not asked for at all. Some, such as British Airways and Ryanair, require it. Others, such as Lufthansa and Swiss, recommend carrying one. Air France says you do not need medical clearance, though it still suggests asking your doctor.
How many weeks pregnant can you fly?
It depends on the airline and on whether you are carrying one baby or more. For one baby, published limits on the pages we checked fall between the 34th and 37th week. For twins, many stop at the 32nd week.
The RCOG leaflet says the safest time to fly with one baby is before 37 weeks. For an uncomplicated twin pregnancy it says before 32 weeks. It also notes that most airlines do not allow you to fly after 37 weeks.
Airlines set their own limits, and they are often earlier than 37 weeks. The table below shows what each airline published when we last checked.
Airline rules last checked
| Airline | Letter or form | How recent | Last week, one baby | Last week, twins or more | Last checked |
|---|---|---|---|---|---|
| British Airways | Form or letter needed from week 28 | As close to travel as possible | Not after the end of the 36th week | Not after the end of the 32nd week | |
| Ryanair | Fit to fly letter from the 28th week | Within 2 weeks of departure | Not beyond the end of the 36th week | Not beyond the end of the 32nd week | |
| easyJet | Not stated on the page we checked | Not stated | Up to the end of the 35th week | Up to the end of the 32nd week | |
| Lufthansa | Certificate recommended beyond the 28th week | "Up to date" | End of the 36th week, or four weeks before the due date | End of the 32nd week | |
| Air France | No medical clearance needed | Not applicable | Advises against flying from week 37 | Not stated | |
| KLM | Clearance from your doctor advised | Not stated | Do not fly at 36 weeks or more | Not stated; ask your doctor | |
| Aer Lingus (Europe) | Travel advice form, weeks 28 to 35 | Not stated | Week 36 or over not permitted | Not stated | |
| Aer Lingus (transatlantic) | Clearance weeks 28 to 33 for departures from North America | Not stated | Week 34 or over not permitted | Not stated | |
| Wizz Air | Medical certificate after the 28th week | Issued within 6 days of the flight | Up to the 34th week | The 32nd week | |
| Vueling | Original medical authorisation, weeks 28 to 35 | Must state its validity dates | Not from 36 weeks | 32 weeks | |
| Swiss | Certificate recommended beyond the 28th week | Not stated | End of the 36th week | End of the 32nd week |
How are pregnancy weeks counted?
Pregnancy weeks are counted from the first day of your last period, not from conception. Your due date sits at 40 weeks, which is 280 days after that first day.
The NHS due date page says pregnancy normally lasts from 37 to 42 weeks from the first day of your last period. The NHS Data Dictionary records days 280 to 286 after the last period as 40 weeks of gestation.
So the tool works backwards from your due date. On any day, your pregnancy in days equals 280 minus the days left until your due date. That number is split into full weeks and spare days.
A dating scan can move your due date. The NHS notes that the 12 week scan gives a more accurate estimate than the period date. If your scan gave a different due date, use the scan date in the tool.
If your cycle is longer or shorter than 28 days, a due date from your period date may be a little out. The NHS calculator lets you adjust for that. If you are unsure, ask your midwife or GP.
What does "the 36th week" mean on an airline page?
This is the part that confuses most people. "32 weeks and 5 days" means you have finished 32 full weeks and are now in your 33rd week.
So "the end of the 36th week" can be read as the day you reach 35 weeks and 6 days. Some people read it as 36 weeks and 6 days. That gap is a whole week.
The tool shows both numbers for every flight. It shows your completed weeks and days, such as 35+5, and your current week, such as "your 36th week". It also uses the stricter reading when it flags a flight as close to a limit.
If your flight falls in that grey week, do not guess. Ask the airline in writing how it reads its own rule, and keep the reply.
What should a pregnancy fit to fly letter say?
A pregnancy fit to fly letter usually needs your due date, a statement that your pregnancy is uncomplicated, and the signature of a doctor or midwife. Some airlines have their own form.
Ryanair's form asks the doctor to confirm three things: the pregnancy is uncomplicated, the expected date of delivery, and that you are fit to fly. It also needs the doctor's signature, date and stamp.
British Airways says its form or letter must be completed, signed and stamped by your doctor or midwife. You show it at check in on the day.
Vueling asks for the original medical authorisation. It must include its period of validity, the doctor's medical board number and the signature.
Aer Lingus has its own Expectant Mother Travel Advice Form for flights within Europe from week 28 to 35.
The NHS warns that getting a letter may cost money and can take several weeks. Ask early, and check whether your airline wants its own form rather than a general letter.
How recent does the letter need to be?
Some airlines set a time limit on how old the letter can be. Others do not publish one.
- Ryanair says the letter should be dated within 2 weeks of the departure date.
- Wizz Air says the certificate must be issued within 6 days of the flight date.
- British Airways asks for a document dated as close to travel as possible. It should cover your whole trip, outbound and return, if you need no medical care while away.
- Vueling asks for the validity period to be written on the document.
- Lufthansa says "up to date" without a number of days.
A short window can catch you out on a longer trip. With Wizz Air, a letter dated just before your outbound flight may be too old for your return two weeks later. The tool flags this and shows the earliest date each letter can carry.
Worked example: a two week trip at 32 to 34 weeks
Here is a made up case to show how the numbers work. The dates are hypothetical and the rules come from the table above.
- Due date: Monday 1 March 2027 (so the last period started on Monday 25 May 2026)
- Outbound flight: Saturday 9 January 2027
- Return flight: Saturday 23 January 2027
- Single pregnancy
Step one is the outbound flight. There are 51 days from 9 January to 1 March. So the pregnancy is 280 minus 51, which is 229 days. That is 32 full weeks and 5 days, written 32+5, in your 33rd week.
Step two is the return flight. There are 37 days from 23 January to 1 March. So the pregnancy is 280 minus 37, which is 243 days. That is 34+5, in your 35th week.
Step three is the airline check. Here is how three airlines from the table treat these two dates.
| Airline | Outbound 9 Jan (32+5) | Return 23 Jan (34+5) |
|---|---|---|
| Ryanair | Letter needed; within limit | Letter needed, dated on or after 9 January; within limit |
| easyJet | Within limit (letter rule not stated) | Within limit, but close to the end of the 35th week |
| Wizz Air | Certificate dated on or after 3 January; within limit | Past the 34th week on the strict reading; just inside on the looser one |
The Wizz Air case is the one to watch. The outbound flight is fine, but the return falls after the 34th week ends on the stricter reading. On that reading the 34th week ends at 33+6, which is 17 January 2027. On the looser reading it ends at 34+6, one day after the flight. When a single day decides it, ask the airline before you book.
For Ryanair, one letter dated in late December would cover the outbound flight. It would be more than 2 weeks old by 23 January. So you would need a second letter for the return.
Now change one input. Make it a twin pregnancy. On the stricter reading, the end of the 32nd week falls at 31+6, which is 3 January 2027. Both flights would then be past the published twin limit for Ryanair, easyJet and Wizz Air.
This is why the tool shows both flights side by side. A trip that starts inside the rules can end outside them.
Is flying safe when you are pregnant?
For an uncomplicated pregnancy, the RCOG says occasional air travel is not harmful for you or your baby. It also says the small amount of radiation on a flight is not considered a risk.
The NHS adds that some people avoid travel in the first 12 weeks because of sickness and tiredness. It notes the risk of miscarriage is higher in the first three months whether you travel or not.
Later in pregnancy, the concern is going into labour away from home. The NHS says labour is more likely after 37 weeks, or around 32 weeks if you are carrying twins.
The RCOG lists situations where you may be advised not to fly. These include a higher risk of early labour, severe anaemia, and recent heavy vaginal bleeding. They also include sickle cell disease with a recent crisis, and a serious lung or heart condition that makes breathing hard.
How to lower the risk of blood clots on a long flight
Flights over four hours carry a small risk of blood clots, and the risk grows with flight length. The NHS and RCOG both suggest a few simple steps.
- Drink water regularly and cut back on caffeine.
- Get up and walk about every 30 minutes or so, or do exercises in your seat.
- Wear loose clothing and choose an aisle seat if you can.
- Ask your midwife or doctor about graduated compression stockings. The RCOG notes these are fitted to you and differ from standard flight socks.
If you have other risk factors, your doctor may suggest heparin injections. The RCOG says you need a doctor's letter to carry them on board. It also says low dose aspirin does not appear to lower the clot risk.
Check your travel insurance too
Your insurance matters as much as the airline rule. The NHS says your policy should cover pregnancy related care, labour, premature birth and the cost of changing your return date if you go into labour.
The RCOG suggests telling your insurer you are pregnant before you travel. It also notes that cover may be harder to get after 37 weeks.
When to see a doctor straight away
Some symptoms need help before any flight, and some need emergency care. Do not wait to see if they pass.
Call 999 in the UK, or your local emergency number elsewhere, if you are pregnant and bleeding with any of these:
- severe tummy pain that stops you doing daily tasks
- pain in your shoulder
- feeling sick, faint or dizzy, or losing consciousness
- heavy bleeding that soaks a pad soon after you put it on
The NHS says to get urgent help from your maternity unit for light bleeding or spotting.
A blood clot in the leg can show as throbbing pain or swelling in one leg, often in the calf. The skin may look red or darker and the veins may look bigger. Get an urgent GP appointment or call NHS 111 if you suspect one.
Call 999 or go to A&E if those leg symptoms come with shortness of breath or chest pain. The NHS warns a clot that reaches the lungs can be life threatening.
If you feel unwell while abroad, use the local emergency number. Do not get on a plane until a doctor has seen you.
How getmedicalcertificate.com can help
We work with doctors who review your case online and issue signed medical certificates. A fit to fly certificate is planned but not yet available.
For a pregnancy letter, many airlines want their own form signed by a doctor or midwife. The doctor who knows your pregnancy is often best placed to complete it.
For other needs, such as a general medical certificate, a doctor reviews your case first. You pay EUR 34.99 only after that review, with no added fees. You get a full refund if the doctor cannot issue it. The signed PDF usually arrives within about 30 minutes of approval. It carries a reference code anyone can check, in seven languages across 42 European countries.
A doctor always decides. See how our doctors review a case
Frequently asked questions
Many airlines ask for a fit to fly letter in pregnancy from about week 28. British Airways, Ryanair, Wizz Air and Vueling require a letter or form from then. Lufthansa and Swiss recommend one. Air France says no medical clearance is needed. Always check your own airline's page before you fly, as rules differ and can change.
It depends on the airline. For one baby, the airline pages we checked set the last week between the 34th and the 37th week. For twins or more, many stop at the 32nd week. The RCOG says the safest time to fly is before 37 weeks with one baby, and before 32 weeks with uncomplicated twins.
Weeks of pregnancy are counted from the first day of your last period, not from conception. Your due date falls at 40 weeks, or 280 days after that day. The NHS says pregnancy normally lasts 37 to 42 weeks from that date. If a dating scan changed your due date, use the scan date when counting your weeks.
A pregnancy fit to fly letter usually states your due date and that your pregnancy is uncomplicated, signed by a doctor or midwife. Ryanair's form also asks the doctor to confirm you are fit to fly, with a signature, date and stamp. Some airlines, such as British Airways and Aer Lingus, have their own form you should use.
It depends on the airline. Ryanair says the letter should be dated within 2 weeks of departure. Wizz Air says the certificate must be issued within 6 days of the flight. British Airways asks for a date as close to travel as possible. On a longer trip, you may need a fresh letter for the return flight.
Yes, within the airline's limit, which is usually earlier than for one baby. British Airways, Ryanair, easyJet, Lufthansa, Wizz Air, Vueling and Swiss publish a limit around the 32nd week for twins or more. Some airlines do not publish a separate twin limit, so contact them. The RCOG says the safest time is before 32 weeks.
If your return date is past the airline's published limit, the airline may refuse to carry you on that flight. The outbound flight being allowed does not change this. Move your return date earlier, choose another airline whose rule fits, or ask the airline in writing before you book. Check your travel insurance too.
Airline wording can be read two ways. Your 36th week runs from 35 weeks and 0 days to 35 weeks and 6 days. Some people read "the end of the 36th week" as 36 weeks and 6 days instead. The gap is a full week, so ask the airline how it reads the rule if you are close.
For an uncomplicated pregnancy, the RCOG says occasional air travel is not harmful for you or your baby. You may be advised not to fly if you are at higher risk of early labour, have severe anaemia, or have had recent heavy bleeding. Ask your midwife or doctor before you book if you have any complications.
For an uncomplicated pregnancy, the airline pages we checked do not ask for a letter before week 28. British Airways says no paperwork is needed before then, and Aer Lingus lists no special requirements up to week 27. If you have had complications, easyJet asks you to consult your doctor before flying at any stage.
This tool and page give general information only. They are not medical or legal advice and do not replace your midwife, doctor or airline. Airline rules can change; always confirm with the airline before you travel.
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