As a result our modern day cities face a number of serious problems which are due to overcrowding. The twentieth century witnesses a major increase in the population in this world. Thus governments educate people to limit the size of their family. Take the China for example, as we noticed that China has approximately 1.3 billion people. That is reason why Chinese enforce the 'one-child policy'.There are also some other reasons for why people do not want more children.  The women now concerned more in their own business, so they don’t want to marry early or produce more children.