In general, your second trimester is the safest, most comfortable time to travel. However, traveling to developing countries at any point during pregnancy brings with it substantial risks, including diseases like malaria and hepatitis, and unknown standards of medical care in case of an emergency. Additionally, traveling to a developing nation often requires a number of vaccinations, some of which are not safe or recommended during pregnancy. And lengthy flights increase the risk of blood clots in the legs (known as deep vein thrombosis).
Source: peo pea