This paper examines a novel mechanism linking fertility and growth. Th
ere are three components to the model: first, increases in capital per
worker raise women's relative wages, since capital is more complement
ary to women's labor input than to men's. Second, increasing women's r
elative wages reduces fertility by raising the cost of children more t
han household income. And third, lower fertility mises the level of ca
pital per worker. This positive feedback loop generates a demographic
transition. a rapid decline in fertility accompanied by accelerated ou
tput growth.