Some women prefer not to travel in the first 12 weeks of pregnancy because of nausea and feeling very tired during these early stages. The risk of miscarriage is also higher in the first three months, whether you're traveling or not.
Travelling in the final months of pregnancy can be tiring and uncomfortable. So, many women find the best time to travel or take a holiday is in mid-pregnancy, between four and six months. Travel during pregnancy is a concern for many women. But if your pregnancy has no complications then there’s no reason why you can’t travel safely, as long as you take the right precautions.”
NHS Choices Teams. (2015). When to travel in pregnancy for NHS Choices [Online]. Available: http://www.nhs.uk/conditions/pregnancy-and-baby/pages/travel-pregnant.aspx [December 02, 2015]