Fertility Measures & Concepts

Complexities of Fertility Analysis Involves 2 individuals of opposite sex Risk is not universal in female population Fecundity Sexual activity Contraception/abortion Repeatable event

(mid-year population) Crude Birth Rate Births in the period 0 to T CBR = Person-yrs lived 0 to T (mid-year population) The CBR is often multiplied by 1,000 and expressed per 1,000 in the population The CBR of Malawi from 1985-90 was 56.3

General Fertility Rate Births in the period 0 to T GFR = Person-yrs lived 0 to T by women ages 15-50 (mid-year population) The GFR is also often multiplied by 1,000 and expressed per 1,000 in the population

Age-Specific Fertility Rates Births in the period 0 to T to women aged x to x+n ASFR = Person-yrs lived 0 to T by women aged x to x+n

Total Fertility Rate Sum of all age specific fertility rates

Variants of TFR Parity specific fertility rates Women at parity “p” Marital fertility rates Married women

Cohort Fertility The mean parity for a cohort of women who have completed their fertility is that cohort’s TFR

Parity Progression Ratio Number of women at parity i+1 or more PPR= Number of women at parity i or more Proportion of a cohort who had at least i live births who went on to have at least one more Box 5.4 (p. 105)

Reproduction Measures Gross Reproduction Rate (GRR) The number of female births an average woman would have if she lived through the end of her reproductive span. Net Reproduction Rate (NRR) The average number of daughters that female members of a birth cohort would bear during their reproductive life span if they were subject to the observed age-specific maternity rates and mortality rates through their lifetimes. NRR=1 equals exact replacement fertility

Why are high birth rates so low?

Proximate Determinants of Fertility Marriage & Marital Disruption Sterility Postpartum Infecundability Fecundability Spontaneous Intrauterine Mortality Contraception Induced Abortion