Chapter 6: Fertility
Basic Concepts and Measures
Fecundity and Fertility
- Fecundity: the physiological ability of a woman, a man, or a couple to reproduce
- Sterility/Infecundity: a total inability to reproduce
- Primary sterility: sterility is present before the individual has had a child
- Secondary sterility: people that have had one child prior to becoming sterile
- Sub-fecundity: the reduced ability of couples to have children because of impairments in any of the biological aspects of reproduction
- Coital inability → disease
- Conceptive failure
- Pregnancy loss
- Fertility: actual reproduction output of a woman, a man, or a couple, as measured by the number of offspring
- Poor countries = high secondary sterility due to poor socioeconomic and unsanitary conditions
- Increase in sub-fecundity in developed countries
- Due to later parenthood
Measures of Fertility
- Period measures: computed on the basis of current information
- Cohort measures: information on specific generations of women
Crude Birth Rate
- CBR: number of births over a specified period per 1000 population
- Overlooks the effect of age on fertility (age differences)
- Doesn’t use the population at risk → all population
General Fertility Rate
- GFR: number of births per 1000 women between the ages 15 and 49
Age-Specific Fertility Rates
- Number of births to a woman of a given age group in a given period for every 1000 women in the same age group
Total Fertility Rate
- TFR: total reproductive output for a given population during a specific interval
- Easily computable and interpretable
- Useful to know whether a population is growing fast enough to replace itself
- TFR of 2.1 = replacement-level fertility
- Total marital fertility rate (TMFR): relates to married women of childbearing age
Gross Reproduction Rate
- GRR: average number of female offspring that women produce
- 1 = 0 population growth
Net Reproduction Rate
- NRR: average number of female births to women after the effect of mortality to women in the reproductive ages has been taken into account
- Life table: reflects the mortality experience of a hypothetical cohort of newborns, followed through life as the cohort ages
Cohort Fertility Rate
- To gain a better sense of future fertility
Society and Fertility: Social-Biological Interactions
Age at Menarche and Age at First Birth
- Age at which the 1st menstruation occurs = influences first birth among women
- Production of hormones
- Secondary sexual characteristics
- Cultural norms
Moral Codes towards Sexuality, Contraception, and Abortion
- Freud: sexual conflict
- Monogamy: social invention to control our natural sexual urges
- Religion: sexual act = sin
- Relaxing of social controls over contraception + abortion nowadays
Seasonality of Conceptions and Births
- High number of conceptions = April - July → avoid giving birth during winter
- Lowest number of conceptions = August - November → crop-gathering months
- Proception: when couples discontinue the use of birth control at the appropriate time in the year as to affect the desired timing of their baby 9 months later
Natural and Human-made Disasters and Fertility
- Fertility drops during wars, famines, and epidemics
- Baby boom → celebrate normal life
- Replacing the children who died
Proximate Determinants of Fertility
Davis and Blake Framework
Intermediate variables:
- Variables that affect exposure to intercourse (unions)
- Variables that affect exposure to conception (contraception)
- Variables that affect gestation and successful parturition of pregnancies (fetal mortality)
Bongaarts’ Proximate Determinants
Proximate variables:
- Extent of marriage
- Extent of contraceptive use
- Extent of induced abortion
- Extent and duration of breast-feeding
Natural Fertility Populations
- Natural fertility: behaviour of couples in earlier populations who did not plan their family size or alter their reproduction habits depending on how many children they already had
- Hutterites → no birth control
- Maximum average fertility for a population = 15.3 births per woman
Theories of Fertility Change
Becker’s Economic Theory
- Demand for children: number of children desired by parents
- Fertility falls as income increases
- Substitution of child quality for child quantity
- High-quality children: those who have more resources spent on them + more time devoted to them
- Low fertility = parents invest in fewer children of greater quality
Easterlin’s Cyclical Theory
- Periods of low fertility are followed by periods of high fertility…
- Important factors
- State of the economy
- Proportion of young workers to older workers
- Type of socialization
- Factors affecting fertility rate among baby boomers
- Cohorts = large
- High material aspirations - context of economic prosperity
- Young adults = career opportunities were more fragile
- Possible return to above-replacement fertility
The Countercyclical Thesis
- Rise in men’s income = more children
- Rise in women’s income = less children
- More earnings lost when a woman takes time off work to have and raise children
- More opportunity costs
Sociological Theories
Second Demographic Transition Perspective
- Countries that have passed the 1st demographic transition experience significant change in several key social demographic dimensions
- Child king → Queen couple
The Individuation Thesis of Lesthaeghe and Surkyn
- When a generation feels satisfied with institutions, young adults tend to marry and raise families early in life (high rates of marriage + fertility) → vice-versa
- Hippie movement
Wealth Flow Theory
- Individual reproductive behaviour is economically rational but modified by non-economic factors to produce the level and pattern of fertility that is observed in a society
- Societies
- Type 1: stable high fertility - net wealth flow from children to parents
- Type 2: economic rationality dictates low levels of reproduction - flows from parents to children
The Synthesis Framework
- Supply and demand for children
- Regulation costs: the costs to parents of intentionally limiting family size
- Background modernization factors + cultural factors → regulation costs, demand + supply of children → proximate determinants of fertility