What should i think about when traveling in the second trimester?

Labor risk: Traveling is usually safe until around 34 weeks. If you have a placenta previa you should not travel late into the 2nd trimester as there is a risk of severe bleeding. If you have a history of preterm labor or early deliveries you may not want to take long airplane trips, an airplane is a bad place to have a premature baby. If you are on a long trip stretch every 2 hours to avoid blood clots.

Avoid if possible.: Travel in pregnancy is not a good idea in general, as far as I am concerned. Emergencies tend to occur unpredictably and you don't want to be a thousand miles from home when they do. Stay put if you are pregnant!