How Humans Control Their Fertility

Abstract Fertility control is an individual right as well as a matter of social and economic consequence. Modern methods of contraception provide couples with an unprecedented ability to regulate their fertility—with implications both obvious and subtle for the epidemiologic study of reproduction. A couple’s desire for children is shaped by their previous pregnancy history, which exerts selective pressures on the distribution of risk among those attempting to conceive. Use of assisted reproductive technologies and prenatal screening leads to further selection. On a global level, the world’s population grew dramatically throughout the late twentieth century and into the 21st, due mostly to the declining mortality of infants and children. Between 1960 and 2000, the global population grew from 3 billion to 6 billion and stands at 8 billion today. While global pregnancy rates are now falling and are approaching replacement levels, the momentum of population growth guarantees continued population expansion for years to come.