All three of the major causes of generational change point toward birth rates either continuing to decline or stabilizing at low rates. Technology makes birth control possible, so having children becomes a choice. Individualism deemphasizes family and tradition, which leads to fewer people choosing to have children. The slow-life strategy means people wait to have children and have fewer of them. These three forces are also behind the declines in sexual activity among both single and married people, and less sexual activity usually means lower fertility.
