The evolution of population growth and population structure is to a large extent determined by the evolution of the birth rate. Even minor fluctuations in reproductive behaviour, both in tempo and in quantum, have far-reaching consequences for population size and structure. A major object of this project is to further our understanding of the nature of below-replacement level fertility.
In the current context of below-replacement fertility, the birth rate is determined chiefly by the timing and number of first and second births. This means that ups and downs in the birth rate are highly determined by who remains childless and by who stops after having one child only. Yet,the apparent lack of data and small number of publications on childlessness are striking. Likewise, there are few studies that address explicitly the process leading to stopping after the first birth. Therefore, instead of dealing with aggregate or mean measures of fertility, this project will concentrate on the lower part of the parity distribution.
Among young adult Europeans, the group that is not sure or ambivalent about whether or not to have any (more) children in the future is much larger than the group that is clear-cut about their future reproductive choices. This finding suggests that eventual family size is highly susceptible to situational factors. A major goal of future studies about childlessness and single child families should be to investigate this in a longitudinal fashion. To what extend do changing household and occupational conditions influence parity progression among nulliparous and primiparous people?
Among people who do want to have children, the two-child norm seems to have weakened during the past decades. In most countries of the European Union, the proportion of young women preferring just one child has doubled during the 1980s. A fundamentally important question is to what extent and in what way these changing norms have behavioural conse¬quences.
Even the best and technically most sophisticated demographic forecasts have a remarkably low level of theoretical sophistication. Therefore, an important aim of the current project is to formulate causal propositions about low fertility. What are the causes of childlessness and the rise of single-child families?