Most pregnant women find that the second trimester, weeks 14 to 27, is the easiest time to travel. You will have recovered from morning sickness and your energy levels are higher than in your first trimester. If you need to fly for business, you may find that a tight schedule of meetings and travel is easier to handle than a long, extended trip. If you have had an uncomplicated pregnancy and you are carrying just one baby, you may be allowed to fly up to your 34th week. Some airlines are unwilling to allow women who are more than 28 weeks pregnant to fly because of the risk of premature labour.
When booking a seat, ticket agents generally won't ask if you're pregnant, but expect to be questioned about your due date at the gate. Any airline can bar you from travel if they have concerns about how far along in your pregnancy you are. To confirm that it's safe for you to fly, have a written permission from your doctor or midwife that includes a confirmed due date, says that you have been examined and are unlikely to go into labour in the next 72 hours. And don't forget to take into consideration how long the trip will be, because you'll have to meet the airline's conditions for flying on the return trip too. And don't fly in small planes with unpressurised cabins.
You should consider other restrictions as well. It only takes a short time to become uncomfortable in an aeroplane seat under normal circumstances, and it even less when you're pregnant. Make realistic travel plans that include the possibility of a medical emergency. Avoid travelling to places where emergency services are not readily available.
You slightly increase your risk of thrombosis (blood clots) and varicose veins if you fly during pregnancy. Keep your circulation flowing and relieve swollen veins by wearing support stocks. Purchase knee-high socks which are specially designed for flying and put the socks on before you get out of bed in the morning and keep them on all day for maximum protection.
Pregnant flight attendants and business travellers who fly hundreds of times a year may have a slightly higher risk of miscarriage or abnormalities in unborn babies due to exposure to natural atmospheric radiation. However, if you only fly a few times a year the risk is negligible.