One of the causes of world population boom

As the urban standard of living upgrades and gets better, increasing rural-urban migration occurs, as the people wants to get a better living. A great deal of this rural-to-urban migration will be to the largest cities of the less developed countries (e.g. Africa) , this major shift of rural population to urban cities enables more people to enjoy modern medicine, lifestyle changes, and improved nutrition, thus granting lower mortality rates and longer life spans, lowering the death rates and results in an increase in world population.