The demographic boom is one of the main causes of the damage we inflict on the planet. Overpopulation refers to the situation when in a region, there are more people than the natural resources can sustain.
This was not a problem along human history, as high natality was compensated by high mortality, due to diseases, natural catastrophes, war and slavery. The growth was very slow. But beginning with the 18th century, improved life conditions, health care and technological advance in industry and agriculture led to the decrease of mortality and an accentuated increase of the population.
By 1920, planet's population was of just 2 billion, while by 1991 was 5.4 billion, being estimated now to be around 6.5 billion and to reach 7 billion by 2012. Some forecasts say the world's population will stabilize to 11.6 billion by 2020, others say it will be around 14 billion or more.
In developing countries, death control was doubled by a drop in natality, especially in the big cities, where large families are hard to sustain. But death control reached developing world, like Africa, Asia, and Latin America only by the middle of the 20th century. Here, death control and increased lifespan, both due to medical care, were not followed by a corresponding drop in natality, partially due to local customs and traditions.
That's why the peak of the recent demographic boom is experienced by the poor countries, exactly those less prepared for facing overpopulation. In the next 50 years, demographic growth will exist only in developing countries. This will increase pressure on the environment, accelerating the disappearance of the rain forests and desertification.
Rapid population growth impedes economic development, due to the high costs of a large number of children that do not contribute to the economy. That's why in developing countries, life standard is precarious.
This explains why many countries have birth control programs. In 1948, Japan legalized contraception and abortion. In 10 years, natality cut down by 50 %. China has 20 % of the world's population and just 2 % of its cultivable surface. It initiated this policy in the '50s, by encouraging couples to delay marriage and have just one child. This succeeded especially in the cities, where the demographic growth decreased from 2.2 % annually during 1965-1980 to 1.4 % in the 1980-1990. This is harder to apply in rural areas, where peasants want heirs and care for the old age.
By 1991, India had 844 million inhabitants and a growth rate of 2.1 % (higher than China). In the '60s, it encouraged the voluntary sterilization of men with more than 4 children, and by the '70s, this was mandatory. This proved not popular and ineffective. Today, India focuses on contraception.
Some developing countries oppose to birth control, considering it a type of western neo-colonialism. This is the case of Catholic Latin America, where abortion and birth control are rejected from religious reasons, while many Muslims prefer large families and many African cultures see in high natality a survival of the ancestors' spirits.
The experience of the developed countries shows that once parents realize their child has higher survival chances, they opt for fewer children, allowing a better care, education and higher life standards. Education makes women see kids raising just a stage in their lives, not the main purpose of their lives. Thus, birth control is connected to economic factors, social protection and woman's emancipation. The former American president Lyndon Johnson said that $ 5 spent on birth control means $ 100 spent on raising the production.