What type of cell, once it enters the tissues, is converted into a macrophage that attacks invaders by phagocytosis?

In a certain region, children are considered economic benefits. a rising trend in the fertility levels of the region is observed. last year the fertility rate in that region was four children per woman. it is predicted that the fertility rate is going to be six children per woman due to increasing poverty. if the predictions are true then the population of that region will , resulting in