This study suggests that reducing fertility should be a primary policy variable used in concert with macroeconomic policies and poverty reduction strategies. It empirically verifies the existence of a poverty demography trap by analyzing survey data from two regions in northern Tanzania. It first summarizes the macro and microeconomic issues of the relationship between GDP and population growth, highlighting poverty and demographic variables in Africa and in Tanzania. The number of children ever born (CEB) and household size in the study area indicate a high rate of population growth. Non-nuclear household members are about 23 percent, indicating heavy population pressure on household resources. The demographic variables were classified with selected poverty indicators (undernutrition and malnutrition; monetary expenditure; and access to land, clean water, sanitary facilities, and energy sources). The results showed moderate undernutrition and acute malnutrition associated with CEB and household size. Large households tend to spend much less on food, compared to smaller households. The mean weekly expenditure among households with six members is a meager US$5. As much as 50 percent of farming households do not own land and depend on wood for energy needs. Access to clean water, modern toilet facilities, and electricity is very poor, especially among large households. Getting out of the poverty trap implies reducing fertility and vice versa.