Firstly, new inventions in medicine now enable us to cure the most deadly diseases and people seem to live longer. Secondly, people don't know how to control the population, especially in the countryside. They don't use any method of birth control and they don't know how to use it. Thirdly, thanks to the development of science and the help of technology, the birth rate is increasing. This is certainly a reason to be proud and happy but it is also a cause of overpopulation. Due to overpopulation, there is a high level of human activity like more travel, more vehicles, more release of sewage, etc. These issues will lead to pollution. People live in overcrowded blocks of flats with noise and the shortage of water. Every day, they have to wait a long line at the bus stops but it is not easy to get a seat on overcrowded buses. The next disadvantage is overcrowded schools which don't have enough playing grounds or study aids for students. Moreover, the larger the population is, the higher the demand for natural resources like water, land, and forests, etc. is. I think the best way to solve overpopulation is through birth control. Birth control may be the policies that limit couples to only one or two children and encourage family planning. Vietnamese government has tried to change the culture of valuing boys over girls which is especially believed by the elderly in the countryside. Therefore, couples don't need to have more children when they don't have a son. There are also family planning classes for couples to raise awareness of family planning

You know, it took hundreds of thousands of years for the world's population to grow to 1 billion. However, in just two centuries, it has grown sevenfold. You know, in 2011, the total world population was 7 billion. And today, about 7.5 billion. Tokyo, with 37.8 million inhabitants, continues to be the largest city in the world in terms of population. Modern medical advances are the main cause of this strong growth in the world's population. It helps to increase birth rates and reduce mortality. The second contribution is the improvement of living standards. This has resulted in an increase in global life expectancy, from 64.8 years in the early 1990s to 70.0 years this year. Last but not least, the number of women of reproductive age is increasing day by day. However, rapid population growth could lead to shortages in health facilities and services and education. The population is growing rapidly, so the energy demand also increases. Therefore, the lack of energy is also a big problem.