Birth and Fertility
birth: the event from the perspective of the newborn; an individual coming into the world at a specific time, and it happens once in a lifetime
CBR (crude birth rate): the total number of births to mothers of all ages that occur during a year
fertility: the status of the parent, almost universally the mother
change in parity: the number of children born to a parent
reproduction: the capacity for a population or subpopulation to sustain its size from generation to generation
natality: the effect that birth and fertility have on a population as a whole
birth & fertility: measured in two ways
period measures: births that occur in women in one or more age groups during a specific calendar year; example: ask how many children were born in a population during a year
cohort measures: track the fertility performance of a specific group of women of similar ages (an age cohort) through the duration of their reproductive years; example: ask how many children a woman delivered during her lifetime
Period measures: ASFR (age-specific fertility rates): the number of births per year by women of a specified age
CBR = B/P x 1,000
TFR (total fertility rate) (calculated from ASFRs): it is a weighted sum obtained by adding together the ASFRs for each cohort
GRR (gross reproduction rate) (similar to TFR): that difference is that only female births are considered
NRR (net reproduction rate): average number of daughters a woman will have if (1) she has children during her reproductive years and (2) her daughters survive to an age at which they can bear at least one daughter
GFR (general fertility rate): the number of births that occur in a population during a year per 1,000 women of childbearing ages alive at midyear
CWR (child woman ration): general fertility experience of all women of childbearing age in relation to the number of living children
Cohort measures: CBR and other period measures can be derived from relevant cohorts
Theories of fertility
The Theory of Multiphasic Demographic Response: the adjustment of reproductive behavior made by a community in response to a rising "strain"
The Theory of Intermediate Variables: a list of variables that are affected by cultural norms & socioeconomic conditions, on one side, and which affect the probabilities of intercourse, conception, and gestation on the other side
Economic, Structural, and Cultural Theories: Emily size is determined by a couples income and the costs they incur in having children
Diffusion Theories: information is exchanged through both public and informal channels
United States: baby boom; rapid economic growth from 1946-1964
China: "One Child Policy"