a)   Improved economic conditions leading to better housing conditions and adequate food supply.

b)  Improvement in hygiene 'such as improved sanitation and clean water supply which prevent diseases leading to reduced death rates.

c)   Effective public health programmes which reduces the infant and maternal mortality rate leading to increased fertility and population size.

d)  Improved medical care-end increased use of modern drugs which reduce the intensity of many killer diseases like measles, and other curable diseases.

e)   Improvements in the level of nutrition and also raises the fertility rate

f)    Early marriages in some societies which lead to high fertility rate among the women since they tend to marry at fertile age.

g)  Increased rate of pre-marital pregnancies among the youths which lead to rapid population growth.