The rapid decline in higher-order births is consistent with the economic explanations for the overall decline in fertility: de-creasing benefits and increasing costs of large families, plus lower costs of birth control through improved contraception and legalized abortion. The demand for one or two children to satisfy the psychic desires of parents is undoubtedly stronger than the demand for higher-order births, and women now find it much easier to control the number of children they bear. It is not just a coincidence that the decrease in the relative importance of higher-order births during the 1960s and early 1970s coincided with the diffusion of birth-control pills and intrauterine devices, two highly effective methods of contraception. When fertility dropped rapidly in the 1930s, the decline was not so heavily concentrated in the higher-order births.