The birth rate (technically, births / population rate) is the total number of live births per 1,000 of a population in a year.  The birth rate of births, births, deaths, and marriages; population counts from a census , and estimated through Specialized demographic techniques. The birth rate (along with mortality and migration rate) are used to calculate population growth .
The crude birth rate is the number of live births per year per 1,000 midyear population   Another term used interchangeably with birth rate is natality .  When the crude death rate is subtracted from the crude birth rate, the result is the rate of natural increase (RNI).  This is equal to the rate of population change. 
The total (crude) birth rate (which includes all-births) -typically indicated as births per 1,000 population-is distinguished from an age-specific rate (the number of births per 1,000 persons in an age group).  The first known use of the term „birth rate“ in English occurred in 1859. 
The average birth rate is 18.5 births per 1,000 total population in 2016.  The death rate is 7.8 per 1,000 per year. The RNI is thus 1.06 percent. In 2012 the average global birth rate was 19,611 according to the World Bank  and 19.15 births per 1,000 total population according to the CIA,  compared to 20.09 per 1,000 total population in 2007. 
The 2016 average of 18.6 births per 1,000 total population is estimated to be about 4.3 births / second or about 256 births / minute for the world.