Some airlines permit babies who are 2 days old to fly, whereas others will only allow babies who are at least 2 weeks old on board.
There are no specific regulations regarding this matter, so check with your airline before booking. In some cases, if your baby is less than 2 weeks old, you may be asked to provide a letter from your GP stating they are fit to fly.
If you have given birth by caesarean section, you may not be allowed to fly until after your 6-week postnatal check-up and if your GP gives you the all clear.
If you have booked your child a seat, you will also have to pre-book an in-flight cot for them. These are usually only available on long-haul flights.
Alternatively, you can arrange with the airline to bring a baby car-seat with you. Very young children should not be allowed to sit in a normal adult aeroplane seat without a travel cot or equivalent.
You should avoid taking a baby to parts of the world where they might be exposed to diseases they are too young to be vaccinated against.
For example, babies younger than 6 months cannot receive a vaccination against yellow fever because of the risk of developing encephalitis, while babies younger than 2 months cannot take anti-malaria tablets.
GOV.UK provides travel and health advice for different countries around the world.
Remember that because of a change in the law, children can no longer travel on a parent's passport. You will need to apply for a passport for your baby if they are travelling to a foreign country with you.