I know from experience that they are serious about the yellow fever vaccine- they will literally give you the shot in the airport before letting you in the country. That applied to Egypt and Madagascar, as well as some others, when I was in Africa. I spent most of my time in Kenya and I was in my second trimester with my son at the time. I got vaccinated for polio, Hep A, meningitis, and took malaria meds. For me, the malaria meds were the most important, as pregnant women who contract malaria have a very high rate of fetal mortality (over 80%). I would find out the requirements of the country and also talk to your doctor about the risks of the vaccines versus the actual likelihood of encountering the disease. For example, rabies was recommended for me, but on further research I found that this really only applied if I planned on having physical contact with animals, so I passed on that one.