The two-child ideal refers to a situation where a family with two children is widely viewed as ideal. This ideal, though historically recent, has acquired widespread acceptance in the last 50 years around the world.
The two-child ideal could be manifested in these forms:
- At the level of ideal fertility: For questions about ideal fertility (questions of the form "How many children should there be in an ideal family?"), a significant majority of people give the answer 2.
- At the level of desired fertility: For questions about desired fertility (questions of the form "How many children would you like in your family?"), a significant majority of people give the answer 2.
- At the level of completed fertility: A significant majority of women have two children over the entire course of their childbearing years.
Widespread societal acceptance of the two-child ideal at the level of completed fertility is one way to work towards replacement fertility (of 2.1). However, it is not the only way: what really matters is that on average, people have two children, and this could be attained by a more spread-out distribution of family sizes (for instance, a number of one-child families and three-child families). However, even if the majority of families have two children, the behavior of the remaining minority could significantly affect overall fertility levels. For instance, if 80% of females have a completed fertility of 2, but the remaining females have no children, completed fertility is 1.6, well below replacement. If, on the other hand, the remaining females average 3 children, fertility is at 2.2, slightly above fertility.
This paper uses the acronym APA to view (1), (2), and (3) above as three stages of societies embracing the two-child ideal.
- Acceptance of the ideal (A): Ideal fertility reaches the two-child ideal.
- Preference for the ideal (P): Desired fertility reaches the two-child ideal.
- Achievement of that preference (A): Expected fertility and completed fertility reach the two-child ideal.