Is it safe to travel to a high altitude while pregnant?

Yes. There are millions of people who live in high altitude areas of the world who are pregnant and do just fine. If you are not used to it you may be more prone to altitude sickness and feeling of shortness of breath though. For prolonged sitting during travel make sure you get up and walk every few hours to prevent blood clots. Support stockings on your feet prevent some swelling too.
Unkown. It is not know whether travel to high altitude poses risk for mother or baby. Limited data is avaialble. Some experts feel that a short trip to less than 12, 000 ft is well tolerated. Check with your obstetrician and travel medicine specialist for information which specifically applies to you. More importantly, you will need to consider vaccines and medications to keep you healthy while you travel.