What Caused The Baby Boom?
There is no consensus regarding the cause of the baby boom: social scientists suggest a complex mixture of economic, social, and psychological factors. The majority of it occurred not through an increase in family size but rather through a sharp decline in the proportion of women choosing to remain childless (Westoff). For many older women these were births postponed during the Depression and World War II. They account for most of the immediate 1946– 1947 "spike" in births associated with returning troops at the end of the war. But in addition younger women departed from a historic upward trend in female labor force participation in order to stay home and start families—a departure that lasted for nearly twenty years. Exhilaration and optimism after the war seemed to combine with a general feeling of affluence in a booming postwar economy, and generous provisions for returning GIs, to make young couples feel able and willing to support children (Bean; Jones).
But this apparently positive relationship between income and fertility fails to explain why fertility rates then suddenly plummeted in the early 1960s, causing the "baby bust." There was a tendency at the time to attribute the decline to the introduction of the birth control pill in 1963—but it is generally acknowledged now that the pill merely facilitated a trend that originated several years earlier, in the late 1950s. Economists have attempted to develop a "unified theory" to explain both the boom and bust. Their focus has been primarily on three factors: male income, the female wage, and material aspirations (desired standard of living). They assume that fertility will tend to rise as male income rises, but fall when material aspirations increase and when female wages rise. The female wage is assumed to represent the value of time foregone in the labor market in favor of childbearing: the "opportunity cost" or "price" of women's time spent in caring for children and hence a significant element in the cost of raising children.
One school of economic thought suggests that the baby boom in the 1950s was caused by rising male incomes and falling women's wages (as women were displaced from wartime jobs), while in the later decades falling male income and rising female wages generated the baby bust (Butz and Ward). Unfortunately data needed to test this hypothesis fully are not available for the complete boom—and bust—period although the data that are available suggest that these two factors account for only a portion of the baby boom (and bust).
However, adding the third factor—material aspirations—provides a more complete explanation for the phenomenon. This third factor has been the focus of another school of thought among economists, which assumes that shifts over time in the desired standard of living temper young adults' responses to intergenerational changes in income. That is, it is assumed that young adults will feel affluent only if their income—regardless of its absolute level—allows them to meet or exceed their material aspirations, which are assumed to be in large part a function of the standard of living they experienced while growing up (Easterlin). And a couple's ability to achieve a given standard of living is affected by the size of their birth cohort relative to that of their parents. An excess supply of younger, less-experienced workers depresses their wages relative to older workers, and excess demand produces the opposite result (Welch; Macunovich, 1999). Since those older workers are the parents of the young adults, and are assumed to affect their children's desired standard of living, it is assumed that large cohorts will have a difficult time achieving their material aspirations—and conversely small cohorts will be favored.
This economic approach assumes that the fertility cycle experienced between 1936 and 1976 was one of the demographic adjustments young adults made in response to "relative cohort size"–induced changes in "relative income." It suggests that the small cohorts born during the Depression entered the labor market in the 1950s with relatively low material aspirations and found themselves favored not only by the strong economy but also by their small relative cohort size. Their high relative income generated the baby boom, but when the boomers themselves entered the labor market in the 1970s and 1980s their experience was diametrically opposed to that of their parents: high material aspirations coming out of their parents' homes, but low earnings relative to those expectations thanks to their large cohort size. The boomers' fertility rates plummeted as they scrambled to maintain their desired standard of living (Macunovich, 1998).