The number of live births per 1,000 of the population over a period of time, usually a year (sometimes it is also expressed as a percentage). For example, a birth rate of 20/1,000 (or 2%) would mean that 20 babies were being born per 1,000 of the population. It is sometimes called crude birth rate because it takes in the whole population, including men and women who are too old to bear children.