Medical writer and editor. Yes, in your first and second trimesters. Although check with your doctor if you've had medical problems during your pregnancy, such as: You may find that your second trimester – weeks 14 to 27 – is the easiest time to travel.Morning sickness is behind you and your energy levels are higher.lying during pregnancy can slightly increase your risk of thrombosis (blood clots) and varicose veins. Wearing support stockings (not tights, which increase your risk of developing thrush), when you fly will help keep your circulation flowing and relieve swollen veins.