Lots of kids in Africa.
My daughter, Jasmine, was born in Bulawayo's Impilo Hospital in '98. After a few years in Zim and then working in the UK, we have been living and travelling between East and Southern Africa for the last 3 years and we have had no medical problems (apart from dentistry). Of course West Africa is a bit more complicated than East or South.
You do not need to take malarials for your whole trip - just when you are in Malaria areas such as Lake Kariba, Lake Malawi, Lake Victoria and other low lying areas. As long as you maintain strict hygeine (personal and with food prep), and your jabs are all up to date, then I foresee no problems.
Sounds like you've got a good span of kids so you should have a great time.