There are some useful tips that may help you avoid medical problems and certainly help to improve your general wellbeing when traveling.  Bringing along a few essentials, knowing when to worry and when not and caring for your body, will contribute to your enjoyment and comfort while you are traveling or vacationing. 

General tips

Physical demands
It may not be the best time to make physically demanding trips.  Even if you are feeling full of energy, your physical abilities have changed, be aware of that when planning your trip.  In addition remember that you should avoid: water or snow skiing, sports with the risk of falling and scuba diving. You should also be more careful with hiking to high altitudes. 

Wining and dining
Whether you still have morning sickness or you're just hungry often, your eating habits have changed according to your new needs.  You should try to have small meals in short intervals to address most of the food issues which are associated with pregnancy (morning sickness, hunger, lack of breath, heaviness, heartburn etc.).  So try to plan your vacation according to this limitation if you suffer from any discomfort.  

Not the best time to travel alone
As independent as you may be, you will probably be more comfortable traveling with another person. This is not a must, but it will make things much easier for you.  Remember, no moving heavy things in or out of overhead compartments, and no carrying suitcases.  Another person with you can make a world of difference to the whole experience.  

Comfort
Different stages of your pregnancy pose changing demands.  You may enjoy camping when you are still in the lightweight stage of pregnancy, but after the 6th month you may not enjoy sleeping in a tent as much as before. So keep in touch with your body's demands.

Stay away from the sun
Your skin is much more sensitive when you're pregnant, so you should avoid the sun as much as possible.  You may notice that when you are in the sun, even for just a little while, your skin develops irregular pigmentation.  Don't worry! It will pass after your delivery.