Birth rate

Crude Birth Rate is the natality or childbirths per 1,000 people per year. It can be mathematically represented by $$CBR = \frac{n}{p}{1000}$$ where n is the number of childbirths in that year, and p is the current population. This figure is combined with the crude death rate to produce the rate of natural population growth (natural in that it does not take into account net migration).

As of 2007, the average birth rate for the whole world is 20.3 per year per 1000 total population, which for a world population of 6.6 billion comes to 134 million babies per year.

Another indicator of fertility is frequently used: the total fertility rate — average number of children born to each woman over the course of her life. In general, the total fertility rate is a better indicator of (current) fertility rates because unlike the crude birth rate it is not affected by the age distribution of the population.

Fertility rates tend to be higher in less economically developed countries and lower in more economically developed countries.

Other methods of measuring birth
General fertility rate -

Standardised birth rate (SBR) – This compares the age-sex structure to a hypothetical standard population.

Total fertility rate (TFR) – The mean number of children a woman is expected to bear during her child-bearing years. It is also independent of the age-sex structure of the population.

Factors affecting birth rate

 * Pro-natalist policies and Antinatalist policies from government
 * Abortion rates
 * Birth control practices
 * Existing age-sex structure
 * Social and religious beliefs - especially in relation to contraception
 * Female literacy rates
 * Economic prosperity (although in theory when the economy is doing well families can afford to have more children in practice the lower the economic prosperity the lower the birth rate).
 * Poverty levels – children can be seen as an economic resource in developing countries as they can earn money.
 * Infant Mortality Rate – a family may have more children if a country's IMR is high as it is likely some of those children will die.
 * Urbanization
 * Typical age of marriage
 * Pension availability
 * Conflict

Socioeconomic Factors
In her 1994 book Pricing the Priceless Child (Princeton University Press), Princeton University sociology professor Viviana Zelizer describes how in the 19th century, children were "economic assets" that contributed to farm work and other important tasks. Then, during the early 20th century, the U.S. established laws removing many children from hard labor, sparking the "rise of the economically useless and emotionally priceless child," Zelizer says.