> The birth rate in cities is strongly anti-correlated with the city size. People just don't feel content and happy to have children in dense cities. Or people

> The birth rate in cities is strongly anti-correlated with the city size. People just don't feel content and happy to have children in dense cities. Or people in big cities have plenty of opportunities and interests than just to have children. People often want to live in big cities due to social reasons, not just due to employment opportunities.