*Causes of the world population boom*

There are three factors that contribute to the increase in world population. One of the causes is decline in the death rate.Nowadays,many people can afford to pay for medical healthcare.Besides this,people also practise hygiene and balanced diet.Thus,this leads to increase in life expectancy which in turn leads to increase in world population. Another cause is growth in birth rate.This maybe due to marriage at earlier age and drop in illegitamacy rate.As there is advanced technology,couple who are infertile can afford to have test-tube babies or adopt children.A growth in birth rate is also perhaps caused by the larger proportion of females compared to men in certain countries.These females who have children play a big role in contributing to the country's population.Not only that,some ethnic groups prefer to have sons.These sons can be their heir to the wealth,carry their surname and even receive dowries.Hence,they will produce more children until they get a son.These indeed give rise to the world population. Lastly,rural-urban migration also contributes to the rise in world population boom. As the people who stay in the urban areas enjoy their standard of living,the people who live in rural areas migrate to the urban areas in search for a better standard of living.