Models of Maternity Histories and Age-Specific Birth Rates

Abstract

At any time point, the size of a population closed to in-and-out migration will increase or decrease, depending on the balance between births and deaths. Consequently, along with the study of mortality discussed in the previous two chapters, the study of fertility, the factors and circumstances underlying the flow of births into a population, has long been of central interest to students of population. In countries in which births are registered according to the age of the mother and estimates of the size of the female population are available by age groups, age-specific birth (fertility) rates are routinely calculated. During the past two decades, however, the investigation of fertility has also been approached through the study of maternity histories, a study that is sometimes referred to as birth interval analysis. With respect to data requirements, the two approaches to investigating fertility are distinct. Period age-specific birth rates provide summary measures of the birth experiences of all women in the childbearing ages during short time periods, consisting of one or more calendar years. Analyzing data on maternity histories, on the other hand, entails following cohorts of women over longer time periods, which may, particularly in the analysis of historical data, include entire reproductive careers, starting with marriage to the onset of physiological sterility.