MORE POWER TO THE PILL:
THE IMPACT OF CONTRACEPTIVE FREEDOM ON WOMEN’S LIFE CYCLE
LABOR SUPPLY*
July 2005
Martha J. Bailey
Abstract:
The release of Enovid in 1960, the first birth control pill, afforded U.S. women unprecedented freedom to plan childbearing and their careers. This paper uses plausibly exogenous variation in state consent laws to evaluate the causal impact of the pill on the timing of first births and extent and intensity of women’s labor-force participation. The results suggest that legal access to the pill before age 21 significantly reduced the likelihood of a first birth before age 22, increased the number of women in the paid labor-force, and raised the number of annual hours worked.
Contact information:
University of Michigan, Department of Economics, 611 Tappan Street, 307 Lorch Hall, Ann Arbor, MI 48109-1220. Phone: 734-647-6874. Fax: 734-764-2769. baileymj@umich.edu
JEL: J13, J22, N32
* Research on this project was generously supported by the Vanderbilt University Summer Research Awards Program in Arts and Science and the NBER. I am grateful to Jeremy Atack, Kathryn Anderson, Dale Ballou, William J. Collins, Andrew Daughety, T. Aldrich Finegan, Claudia Goldin, Melanie Guldi, Theodore Joyce, Derek Laing, Robert A. Margo, Walter Oi, Jennifer Reinganum, John Siegfried, Gary Solon, and workshop participants at Vanderbilt and Harvard Universities and the NBER Summer Institute. I also thank three anonymous referees and the editors for helpful comments and suggestions. Dan Taylor provided outstanding research assistance.
I.Introduction
The movement she [Margaret Sanger] started will grow to be, a hundred years from now, the most
influential of all time. When the history of our civilization is written, it will be a biological history,
and Margaret Sanger will be its heroine.1
--H.G. Wells, 1931
The release of Enovid in 1960, the first birth control pill, afforded U.S. women unprecedented freedom to plan childbearing and their careers. For college women, Goldin and Katz [2002] find that access to oral contraception led to a later age at first marriage and greater representation in non-traditional, professional occupations. But “the pill” may have had durable and far-reaching effects on women’s labor market work across levels of attainment.
Relatively little work in economics, either theoretical or empirical, has explicitly examined the impact of oral contraception on women’s paid work. Indeed, this line of research may seem relatively unimportant given the compendium of historical, cross-country, and scholarly research that suggests that birth control mattered very little [cf. Becker 1991, ch. 4]. Well before the advent of the pill, the U.S. witnessed steady increases in women’s labor-force participation and dramatic swings in fertility. In light of this fact, Becker’s conclusion summarizes a view held by many scholars: “the ‘contraceptive revolution’ … ushered in by the pill has probably not been a major cause of the sharp drop in fertility in recent decades” [1991, p. 143]. But even if the pill did reduce fertility, recent quasi-experimental research suggests that declining numbers of children can explain remarkably little of the longer-term changes in women’s market work [Bronars and Grogger 1994; Jacobsen, Pearce, an
d Rosenbloom 1999; Hotz, McElroy and Sanders 1997; Angrist and Evans 1998].2
The relative scarcity of empirical evidence on the impact of oral contraception relates to the difficulty of the empirical problem. The pill’s introduction in 1960 and subsequent diffusion corresponded to the resurgence of the women’s movement, the spread of labor-saving household technologies, the enactment and increasing enforcement of anti-discrimination legislation, and the social unrest associated with the Civil Rights Movement and Vietnam. Moreover, abortion became increasingly available around the time many young women gained access to the pill and may have had comparable effects on their fertility and labor market decisions. Similar to the strategy used by
1 Margaret Sanger (1879-1966) is known as the founder of the twentieth century’s birth control movement.
抽油机节能2 Angrist and Evans [1998, p. 474] conclude that since 1950, “the increase in female labor-force participation has been so large that declining fertility can explain only a small fraction of the overall change.” Between 1970 and 1990, the same authors suggest that the decline in 2015上海工博会
Goldin and Katz [2002], I exploit a source of plausibly exogenous variation to isolate the pill’s impact on women’s lifecycle labor-force participation. This variation arises from broad, state-level changes f
rom 1960 to 1976 that expanded the legal rights of individuals ages 18 to 21. The indirect effect of these legal revisions, however, was to empower unmarried women under the age of 21 to consent to medical care and, by extension, obtain oral contraception without parental consent.
These laws facilitate two types of analysis of the pill’s impact. First, they shaped the diffusion of the pill to younger women from 1960 to 1976 and provide a rough timeframe over which to look for relevant changes in behavior. Figure I displays trends in first birth rates by age category since 1940. Although first births among younger women increased during the Baby Boom, a marked decline in early childbearing began when the pill was introduced and lasted until 1976, when all unmarried minors in the U.S. could obtain contraceptives under the law. Notably the largest absolute declines occurred during this period among 18 to 19 year olds, the group of women most likely to benefit from liberalized access laws. In contrast, first birth rates among 15 to 17 year olds, individuals who were generally too young to benefit, underwent almost no discernible changes.
Changes in the distribution of the age at first birth also correspond closely to the diffusion of the pill. Figure II plots the fraction of women first giving birth in three-year age bins by cohort. For example, the point above age 18 denotes the fraction of women with a first birth within the age bin of 17 to 19. Among women born before 1940 who were too old to benefit from early access, approximately 62 pe
rcent of those ever having children report a first birth by age 22. For women born around 1955—almost all of whom had access to the pill under the law—the fraction giving birth by age 22 had declined by 16 percentage points, or roughly 25 percent.3 Stark differences between cohorts with (1955 to 1960) and without (1933 to 1940) early access to the pill suggest that these changes are not due to pre-existing trends. Moreover, there appear to be almost no visible changes in the distributions after 1955, when all young women would have had early access.4
A rapid transformation in women’s lifecycle labor-force participation profiles occurred between the cohorts of childbearing beyond the second child among women ages 21 to 35 can account for roughly two percentage points (of the total 16.8 increase)
in employment.
3 The cohort of 1955 is relevant because the U.S. Supreme Court decision, Planned Parenthood of Central Missouri v. Danforth, in 1976 ruled against a state’s compelling interest to regulate access to contraception based on age alone.
bmk4 The oldest women observed in the 195
metropolis算法5 to 1960 birth cohorts were ages 40 and 35 respectively in the 1995 June CPS, the last survey to ask about the year the first child was born. To the extent that women in these cohorts delayed their first births beyond ages 35 and 40, the fraction of women born between 1955 and 1960 giving birth at earlier ages should be overstated and those delaying understated. Therefore, the
1940 and 1955 as well. As shown in Figure III, women born during the first forty years of the century tended to withdraw from the labor-force during the ages of high fertility. As more women returned to work after their children had grown, increases in the market participation of women over 30, especially married women, drove increases in aggregate participation rates (cf. Goldin [1990]) until the 1960s. This pattern reverses with cohorts born after 1940. For those born in 1955, the “fertility dip” in labor-force participation had completely disappeared. Participation rates were 24 percentage points higher at age 25, and 20 percentage points higher at age 30, than those of women born in 1940.5 This rapid, inter-cohort shift in young women’s labor market participation during the twentieth century occurred over the same period as younger and unmarried women gained legal access to oral contraceptives.
While cross-cohort trends are suggestive, the remainder of this paper examines average within cohort effects of early access using implied legal variation by year of birth and state for women born
诗人的别称from 1940 to 1955. The estimates suggest that access to the pill before age 21 reduced the likelihood of becoming a mother before age 22 by 14 to 18 percent and increased the extent of 26 to 30 year old women’s labor-force participation by approximately 8 percent. At the intensive margin, women with early access worked at least 68 more annual hours at ages 26 to 30. These findings do not challenge the validity of past research on the relationship between the number of children and women’s labor supply. Rather, they are consistent with the notion that the pill catalyzed changes in labor-force participation through the mechanism of birth timing. By providing a low cost means of delaying childbearing, oral contraception allowed women to remain in school, pursue longer-term careers, and work more in the paid labor-force during ages historically associated with childrearing. II.The theoretical impact of early access to the pill on women’s lifecycle labor supply While a number of relatively effective contraceptive methods were available well before the introduction of Enovid in 1960, oral contraception revolutionized the technology of birth control in three important ways.6 First, the pill constituted the first female contraceptive. A woman could independently decide to take the pill; it did not
inability to observe younger cohorts at older ages tends to make the shift between 1940 and 1955 appear smaller than it is.
5 Smith and Ward [1985, p. S65] also note that for women born after 1950, there is no observable employment decline over the childbearing years. Goldin [2002, Figures 4 and 5] notes that these trends are borne out for married women as well, although the labor market integration of college graduate women appears to have begun earlier.
6 The withdrawal method, or coitus interruptus, had been used well before it was popularized in the U.S. in Robert Dale Owen’s 1831 pamphlet, Moral Physiology. A number of other contraceptive methods, such as the condom and diaphragm, had also been adopted before the pill was available [Brodie 1994]. For a thorough history of the condom, see Brandt [1985] and Valdiserri [1988].
require the consent or knowledge of men or discomfort to either party during sex. The pill transferred control of contraception, which had long resided with men, to women who bore the high physical and opportunity costs of childbearing. Second, the pill divorced the decision to use contraception from the time of intercourse. This lowered the marginal costs of preventing births during sex to zero and shifted decisions about contraception to times separate from the act of intimacy. Third, the pill’s effectiveness far exceeded that of all other methods available in 1960.7 Whereas most couples regarded pregnancy risk as part of the cost of intercourse, oral contraception virtually eliminated concerns about unwanted conception [Michael and Willis 1972, Willis 1973, Marks 2001]. By reduci
ng the costs of preventing and timing childbirth, improvements in the technology of birth control may have mitigated the constraints imposed by fecundity on women’s labor-force participation. As a result, more women may have entered and remained in the paid workforce.
松潘地震One might infer from recent studies that the potential effect of the pill on women’s fertility and labor-force participation is small. Using biological events to identify the impact of an additional child on women’s labor supply, the bulk of compelling research finds only a modest effect (twinning [Bronars and Grogger 1994; Jacobsen, Pearce, and Rosenbloom 1999] or miscarriages [Hotz, McElroy and Sanders 1997], or the sex of children already born [Angrist and Evans 1998]). Using variation in the number of births may understate the pill’s impact for two reasons. First, only women who chose to become pregnant (or for whom prevention was too costly) enter the sample. The impact of an unexpected birth may be considerably smaller for these women than for those who are childless or are not expecting a child. Second, these studies abstract from the pill’s potential effect on labor supply through birth timing.8 Because couples were fairly accurate at reaching their target fertility before the pill, fairly costless birth timing technology may be among its most important contributions.9
The empirical exercise in this paper allows one to assess the importance of the pill through birth timi
ng using
7 From the beginning, Enovid’s advocates promoted the pill as 99 percent effective. Although numbers on the effectiveness of contraception are dubious at best, Planned Parenthood estimates the failure rates associated with typical use of the condoms available today at around 15 percent and the failure rates of today’s modern diaphragms at around 16 percent. It is unclear how much of this figure is attributable to inappropriate use. Less effective spermicides and materials imply that failure rates of these methods would have been much higher in 1960.
8 Klepinger et al. [1999] provide an excellent review of studies that relate early childbearing to women’s outcomes including education, experience, labor-force participation and wages. Most find that early childbearing has a negative effect on each of these outcomes. Miller [2005] and Vere [2004] also examine the impact of birth timing.
9 The pill revolutionized a couple’s ability to time childbearing. Primitive methods of birth control included delay of first marriage, longer breast-feeding to delay the return of menses, withdrawal and the reduced frequency of coitus. Modern alternatives were condoms and diaphragms. Couples anticipated periodic failure of any of these methods and most employed a variety of methods to hit th
eir target fertility. Before the pill, no method—save abstinence—facilitated the deliberate timing of childbearing.
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