Table 1.

Key citations and related predictions for three classes of models of fertility decline

Risk/mortality models*†	Economic/investment models*†	Cultural transmission models*†
1. Classic Demographic Transition Theory (13): Fertility declines with reductions in infant mortality, increases in development	1. Wealth Flows (19, 21): Fertility declines with the reduction in child productivity, following a shift away from agriculture	1. Diffusion (32, 34): Fertility declines with critical mass of low fertility innovators or mass media technology
2. Childhood Environment (15): Fertility declines with decreases in local mortality rates or chronic stress	2. Human Capital (22)/Embodied Capital (23)/Unified Growth Theory (18): Fertility declines with increasing payoffs to investment in human capital in modern labor markets	2. Social Network Effects (35, 36): Fertility declines with changes in social network structure that foster transmission of new information or adoption of new fertility behaviors
3. Extrinsic Risk (14): Fertility declines with decreases in extrinsic mortality, especially in infancy and childhood	2a. Women’s Opportunity Costs (27–29): Increasing investment in women’s education and careers produce a tradeoff with children and/or delays in childbearing	3. Cultural Evolution (37, 38): Fertility declines with an increasing number of high prestige adopters of low fertility
4. Variance Compensation (16): Fertility declines with decreasing mortality rates, variance in mortality	2b. Investment in Child Quality (22, 23): Increasing payoffs to investments in children motivate parents to have fewer children and increase tradeoffs between children	4. Kin Influence (39): Fertility declines with decreasing interactions with kin, increasing interactions with nonkin
5. Unified Growth Theory (17, 18): Fertility declines with increasing adult lifespan, increasing child survival rates	2c. Rising Costs of Children (22, 25): Fertility declines with increasing costs of raising children, especially when wealth is heritable

^*Given space constraints, we focus here on some of the best-known models from several disciplines.

^†The models discussed often have numerous predictions. We focus on those amenable to modeling with our sample.