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:

  1. Variables that affect exposure to intercourse (unions)

  2. Variables that affect exposure to conception (contraception)

  3. Variables that affect gestation and successful parturition of pregnancies (fetal mortality)

Bongaarts’ Proximate Determinants

• Proximate variables:

  1. Extent of marriage

  2. Extent of contraceptive use

  3. Extent of induced abortion

  4. 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