The major causes of rapid population growth in Nepal are as follows:

1. Polygamy: Polygamy is also one of the causes of the population increasing. A man gets married to multiple women, and these women give birth to more babies. 
   
   
2.  Cultural factors: Many people do not want to apply measures of family planning. They think it is unholy to use family planning measures and prevent conception. They believe that the birth of a child is a gift of God. So they do not want to stop births.
   
   
3.  Religious Factors: In Nepal, social and religious values and customs are mainly based on the orthodox attitudes of people. Parents do not get respect in society if they have no children especially a son. It is the conservative belief that the son is necessary to inherit parental property, continue the family line, and perform the funeral rites and shraddha (annual ritual) of his parents. Such attitude and practice lead to an increase in population in Nepal. 
4.  Illiteracy:  illiteracy is the main cause of population growth. The inability to read or write or the actual or perceived state of being uneducated or insufficiently educated is called illiteracy.they have not knowledge about family planning to control the population.
5. Early marriage: Early marriage is the act of getting married at a younger age when the individual is not fully mature. early marriage and population growth and explained that when girls marry early, they had more years to have children, resulting in many of them giving birth to several children.
6. Poverty: Poverty does cause population growth and population growth does cause poverty. Economic development means increasing control of both parts of the cycle; the ability to choose your family size, and the ability to make a living with something more than your hands and the hands of your children.