The Wages of Sin: How the Discovery of Penicillin Reshaped Modern Sexuality Andrew M. Francis It was not until 1943, amid world war, that penicillin was found to be an effective treatment for syphilis. This study investigated the hypothesis that a decrease in the cost of syphilis due to penicillin spurred an increase in risky non-traditional sex. Using nationally comprehensive vital statistics, this study found evidence that the era of modern sexuality originated in the mid to late 1950s. Measures of risky non-traditional sexual behavior began to rise during this period. These trends appeared to coincide with the collapse of the syphilis epidemic. Syphilis incidence reached an all-time low in 1957, and syphilis deaths fell rapidly during the 1940s and early 1950s. Regression analysis demonstrated that most measures of sexual behavior significantly increased immediately following the collapse of syphilis, and most measures were significantly associated with the syphilis death rate. Together, the findings supported the notion that the discovery of penicillin decreased the cost of syphilis and thereby played an important role in shaping modern sexuality. Key words: sexual behavior; syphilis; penicillin; sexual revolution; 1950s

                                                             * Andrew Francis, Department of Economics, Emory University ([email protected]). The author would like to thank Robert Nelson, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP), Centers for Disease Control and Prevention (CDC), for providing historical data on syphilis and gonorrhea incidence.

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INTRODUCTION There is some evidence that cohorts of young adults after the mid-1960s exhibited a greater number of sexual partners as well as a greater likelihood of premarital sex, among other changes in sexual behavior (Laumann et al., 1994; Michael et al., 1994). Traditional explanations for this so-called "sexual revolution" have focused on the spread of the birth control pill, increasingly permissive attitudes toward sex, and shifting moral values during the 1960s and 1970s (Allyn, 2000; Brandt, 1985, 1988; Brown, 2006). But scholars are quick to point out that nationally representative data are strikingly thin prior to the AIDS epidemic, and that many factors contributed to these trends, which may have begun as early as the 1920s. Indeed, debate rages about whether changes in sexual behavior were continuous or discontinuous, gradual or dramatic, evolutionary or revolutionary (Allyn, 2000; Bolin & Whelehan, 2009; Laumann et al., 1994; McLaren, 1999; Michael et al., 1994; Rathus et al., 2005). Many interrelated factors undoubtedly played a role in shaping modern sexuality. Nevertheless, it is important to consider an explanation suggested by some physicians and public health officials in the 1950s but not investigated in any systematic way: the discovery of penicillin. Penicillin was discovered in 1928 by Alexander Fleming and first put into clinical use in 1941 by a University of Oxford research team including Howard Florey and Ernst Chain (Brown, 2006). Even though a chemotherapy treatment was developed in 1909 by Paul Ehrlich, it was not until 1943, against the backdrop of high syphilis deaths and escalating world war, that penicillin was found to be an effective treatment for syphilis. In the United States, the exigencies of war spurred a large-scale public health effort to eradicate syphilis first among the military and then among the population (Brown, 2006). As a result, the number of syphilis cases and deaths

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fell precipitously during the late 1940s and early 1950s. It appeared like the collapse of the syphilis epidemic had occurred by the mid-1950s. In fact, there was a substantial decrease in the "cost" of acquiring syphilis in terms of reductions in death, morbidity, and economic loss. The hypothesis of this study is that a decrease in the cost of syphilis due to the development of penicillin induced an increase in risky non-traditional sex. Risky non-traditional sex is nonmarital sexual behavior associated with an elevated likelihood of STD transmission. Using nationally comprehensive vital statistics from the 1930s to the 1970s, this study describes the rise of risky non-traditional sexual behavior, characterizes the cost of syphilis, and estimates the relationship between the cost of syphilis and sexual behavior. Measures of sexual behavior include the gonorrhea rate, illegitimate birth ratio, and teen birth share. Exploring this hypothesis makes a contribution not only because it casts the origin of modern sexuality in a new light, but also because the historical syphilis epidemic parallels the contemporary AIDS epidemic in ways that yield lessons about the relationship between behavior and disease, which may help to improve health policy toward AIDS as well as future STDs yet to arise.

METHOD The objectives of the present study were to describe the emergence of the era of modern sexuality, to measure the cost of syphilis, and to estimate the relationship between the cost of syphilis and sexual behavior. This section explains the data and methods employed.

Data Nationally representative data on sexual behavior are strikingly limited prior to the AIDS epidemic. With his two-volume Kinsey Report in 1948 and 1953, Alfred Kinsey made a major

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contribution to the empirical study of sexuality. However, his lack of probability sampling severely limited the generalizability of his results (Laumann et al., 1994). Early surveys (e.g., Growth of American Families conducted in 1955 and 1960) only interviewed married women and eschewed questions about sexual behavior before marriage. Later surveys (e.g., National Survey of Family Growth conducted in 1982) asked retrospectively about sexual behavior before marriage but few participants were young women in the 1950s and state of residence was unknown. Nonetheless, some nationally comprehensive vital statistics were collected and published by the federal government during the period of interest. Three variables served as measures of risky non-traditional sexual behavior: the gonorrhea incidence rate, the number of new gonorrhea cases per 100,000 population; the illegitimate birth ratio, the number of births to unmarried mothers per 1,000 live births; and the teen birth share, the percentage of live births to women age 19 or younger. All three variables were available at the state-level. The gonorrhea rate was available from 1941, while the illegitimate birth ratio and teen birth share were available from 1937 for both whites and nonwhites. Data on births to unmarried mothers were missing for some states in some years. Data on gonorrhea were from a historical CDC report digitized by CDC staff at the request of the author (U.S. Public Health Service, 1963). Data on births to unmarried women and teens were from historical editions of Vital Statistics of the United States and were digitized by the author (CDC, 1937-1975). Two variables served as measures of the cost of syphilis: a set of indicators for the number of years since the collapse of syphilis, defined as the year when the three-year moving average of new syphilis cases reached a minimum (3 years ago or fewer, 4-7 years ago, and so on); and the syphilis death rate, the number of deaths attributable to syphilis per 100,000

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population. Both variables were available at the state-level. The number and rate of new syphilis cases were available from 1941, while the syphilis death rate was available from 1937. Data on syphilis cases were from a historical CDC report digitized by CDC staff at the request of the author (U.S. Public Health Service, 1963). Data on syphilis deaths were from historical editions of Vital Statistics of the United States and were digitized by the author (CDC, 1937-1975). Additionally, several variables were used as state-year covariates in the regression analysis: average real income per capita; average real expenditures per public school student; percentage with a college degree; marriage rate, the number of marriages per 1,000 population; and birth rate, the number of births per 1,000 population. Percentage with a college degree was linearly interpolated between missing years of data. All of these variables were available at the state-level and were from the Statistical Abstract of the United States (U.S. Census Bureau, 1937-1975). Lastly, a number of variables were constructed to evaluate alternative hypotheses. Two of these were national measures of the spread of contraceptive technology: family planning services, the percentage of unmarried women age 16 to 30 who ever had received family planning services, which signals access to the birth control pill; and the abortion ratio, the number of abortions per 1,000 live births. Receipt of family planning services was calculated by the author using the National Survey of Family Growth (U.S. Department of Health and Human Services, 2000), and the abortion ratio was from a CDC surveillance report (Gamble et al., 2008). Other variables were calculated using General Social Surveys 1973-2008 (Davis, Smith, & Marsden, 2010). One set measured national trends in permissive attitudes towards sex by birth cohort: permissiveness toward premarital sex, the proportion of participants who reported that

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sexual relations before marriage between a man and woman is wrong only sometimes or not wrong at all; permissiveness toward abortion, the proportion of participants who reported that it should be possible for a pregnant woman to obtain a legal abortion if the woman wants it for any reason; and permissiveness toward same-sex sex, the proportion of participants who reported that sexual relations between two adults of the same sex is wrong only sometimes or not wrong at all. Another set measured national trends in religious affiliation and attendance by birth cohort: the proportion of participants who reported that they had a religious preference other than "none", attended religious services once a year or more, and attended religious services once a month or more.

Estimating the Cost of Syphilis Apart from examining time trends in syphilis cases and deaths, two exercises were conducted to measure the cost of syphilis before and after the development of penicillin. One exercise compared syphilis deaths in 1939 with AIDS deaths in 1995. 1939 was the deadliest year for syphilis with almost 20,000 deaths attributable to the disease, while 1995 was the deadliest year for AIDS with more than 40,000 deaths. Using vital statistics data, death rates (the number of deaths per 100,000 population) and death shares (the percentage of deaths of any cause) were calculated by gender, race, and age for both diseases (CDC, 1937-1975, 1979-1998). A further exercise estimated the cost of syphilis for a sexually-active adult in the mid1940s, at a time just prior to the widespread availability of effective treatment. In particular, this exercise sought to approximate the number of people recently infected with syphilis as of the mid-1940s, the probability a randomly-selected sexual partner would be infected with syphilis, and the probability of syphilis death if one's sexual partner were infected. Epidemiological and

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medical features of syphilis (e.g., the ratio of new infections to deaths, per-contact probability of transmission, percentage of untreated infected people developing tertiary stage syphilis) were used to produce these rough estimates (CDC, 1937-1975; Liu, Euerle, & Chandrasekar, 2010; Porter & Kaplan, 2011; U.S. Census Bureau, 2011; U.S. Public Health Service, 1963).

State Panel Regressions Regression analyses were conducted to estimate the relationship between measures of the cost of syphilis and measures of sexual behavior. To do so, a U.S. state-level panel dataset spanning from 1937 to 1975 was constructed. Ordinary Least Squares (OLS) estimation was performed using Stata (version 11). To investigate the collapse of syphilis—whether the change in sexual behavior was temporary or permanent, immediate or delayed—each of the measures of sexual behavior was regressed on a set of indicators for the number of years since the collapse of syphilis, state fixed effects, and decade fixed effects. Recall that the collapse of syphilis was defined as the year when the three-year moving average of new syphilis cases reached a minimum. State fixed effects controlled for state-specific time-invariant factors, while decade fixed effects controlled for decade-specific state-invariant (i.e., national) factors. Since the reference category was the time period prior to the collapse of syphilis, the estimated coefficients indicate the change in sexual behavior relative to pre-collapse levels. The following equation was estimated for state s and year t: Ys ,t    k * C sk,t   s     s ,t , k

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where Y was a measure of sexual behavior, C an indicator for the number of years since the collapse of syphilis,  a state fixed effect, and  a decade fixed effect. To investigate the syphilis death rate, each of the measures of sexual behavior was regressed on the syphilis death rate, state fixed effects, decade fixed effects, state-specific linear year trends, and state-year covariates. State fixed effects controlled for state-specific timeinvariant factors, decade fixed effects controlled for decade-specific state-invariant (i.e., national) factors, and year trends controlled for state-specific factors that were increasing or decreasing linearly. The following equation was estimated for state s and year t: Y s ,t   * D s ,t   s     s * t   * X s ,t   s , t ,

where Y was a measure of sexual behavior, D the syphilis death rate,  a state fixed effect,  a decade fixed effect,  a state-specific linear year trend, and X a vector of state-year covariates. Robust standard errors were adjusted for clustering on states. All regressions were weighted by state population share. Note that the results were robust to state population weighting, as unweighted regressions yielded analogous results.

RESULTS Era of Modern Sexuality Figure 1 depicts trends in three measures of risky non-traditional sexual behavior between 1941 and 1975. In order to plot the variables together, each of the variables was standardized to have a mean of zero and a SD of one. As the figure shows, gonorrhea rose moderately during World War II, reached a minimum in 1957, and rose steeply thereafter. From 1957 to 1975, the gonorrhea rate increased by almost 300 percent. Illegitimate births remained relatively constant between 1941 and 1953 and began to rise steadily in the mid-1950s. From

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1955 to 1975, the white illegitimate birth ratio increased by about 250 percent. Teen births decreased during World War II, returned to pre-war levels by the early 1950s, and began to rise dramatically in the mid-1950s. From 1955 to 1975, the white teen birth share increased by almost 50 percent. As Figure 2 shows, the non-white illegitimate birth ratio and teen birth share exhibited analogous patterns.

Decreasing Cost of Syphilis Numerical estimates imply that fear of syphilis death loomed large prior to the development of an effective treatment. Table 1 compares syphilis and AIDS at the height of their epidemics. In both rates and shares, syphilis deaths in 1939 and AIDS deaths in 1995 were approximately the same order of magnitude. Overall, the syphilis death rate was 15.0, while the AIDS deaths rate was 16.2; syphilis accounted for 1.4% of all deaths, while AIDS accounted for 1.9% of all deaths. AIDS, however, was more deadly for men, which is expected given HIV was concentrated among men who have sex with men. Table 2 calculates syphilis risk for a sexuallyactive adult in the mid-1940s. Based on parameter values, it was estimated that more than six hundred thousand Americans were recently infected with syphilis as of the mid-1940s, the probability a randomly-selected sexual partner would be infected with syphilis was about 1.04%, and the probability of syphilis death if one's sexual partner were infected was approximately 6.41%. This study hypothesized that the discovery of penicillin induced a precipitous fall in the cost of syphilis. Figure 3 depicts the collapse of syphilis following World War II. The syphilis incidence rate reached an all-time high in 1947, amid the national public health campaign to eradicate syphilis, and reached an all-time low in 1957. The syphilis death rate fell rapidly during

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the 1940s and early 1950s. From 1947 to 1957, syphilis incidence fell by 95 percent and syphilis deaths fell by 75 percent.

Regression Analysis Table 3 reports the coefficients from regressions of measures of sexual behavior on indicators for the number of years since the collapse of syphilis, state fixed effects, and decade fixed effects. The year when syphilis collapsed, the minimum of the three-year moving average of new cases, varied across states between 1954 and 1959. Mirroring trends in Figure 1, all of the measures increased as the number of years since the collapse of syphilis increased. With controls for decade, the coefficient on “3 or fewer” was positive and significant for both the white and non-white illegitimate birth ratio and teen birth share, indicating that, relative to pre-collapse levels, the measures demonstrated significantly higher values immediately following the collapse. In contrast, the coefficient on “3 or fewer” for the gonorrhea rate was not positive, presumably because pre-collapse levels were temporarily elevated during the war. Table 4 reports the coefficients from regressions of measures of sexual behavior on the syphilis death rate (logged), state fixed effects, decade fixed effects, state-specific linear year trends, and state-year covariates. All but one of the coefficients in the table were negative and significant, providing evidence that the syphilis death rate was inversely associated with the gonorrhea rate, white and non-white illegitimate birth ratio, and non-white teen birth share. For example, estimates in the final column suggest that a decrease in the syphilis death rate of the magnitude that occurred between 1940 and 1960 was associated with a 16% increase in the gonorrhea rate. However, the syphilis death rate was not negatively associated with the white teen birth share in the final column.

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Alternative Hypotheses There are several alternative hypotheses about the era of modern sexuality. It is crucial to acknowledge that these hypotheses are mutually compatible with the hypothesis of this paper, and that it is likely many of these causal factors had interacted with the cost of sexual behavior and with one another, rather than operating independently. One of the most prevalent explanations for the rise in risky non-traditional sexual behavior is the development of contraceptive technology during the 1960s and 1970s (Brandt, 1985; Brown, 2006; Marshall & Donovan, 1991; May, 2010). Indeed, usage of contraceptive technology, especially the birth control pill, was rising at a time when measures of risky nontraditional sexual behavior were also rising. However, the timing of these changes did not precisely coincide. Figure 3 illustrates that the percentage of unmarried women receiving family planning services started to increase in the mid-1960s, and the abortion ratio started to increase in the early 1970s. Research indicates that rapid diffusion of the pill to unmarried collegeeducated women occurred in the early 1970s (Goldin & Katz, 2002). It was not until 1972 that the U.S. Supreme Court allowed all unmarried couples access to the pill. Moreover, studies of more recent periods find little evidence that the availability of contraceptive technology increased risky sexual behavior (Kane & Staiger, 1996; Lichter, McLaughlin, & Ribar, 1998; Lundberg & Plotnick, 1990; Paton, 2002; Raine et al., 2005; Santelli et al., 2007). Another common hypothesis relates to liberalizing attitudes and moral values during the 1960s and 1970s (Brandt, 1985; Brown, 2006). Figure 4 displays permissive attitudes toward sex by birth cohort. This may provide insight about time trends in attitudes since susceptibility to attitude change significantly declines after early adulthood (Krosnick & Alwin, 1989). As the

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figure shows, permissive attitudes towards premarital sex, abortion, and same-sex sex had been rising gradually throughout the twentieth century. Figure 5 illustrates religious behavior by birth cohort. It indicates that religious affiliation and attendance had also been moving gradually during the century. Thus, although measures of attitudes toward sex and religion were moving while measures of risky non-traditional sexual behavior were also moving, there were no discontinuous changes in attitudes or religion for cohorts who were young adults in the 1950s. Furthermore, an important hypothesis is the decline in federal funding for STD control after World War II (Anderson, 1965; Brandt, 1985, 1988). Although this may explain the rise in STDs, it is unable to explain the rise in risky non-traditional sexual behavior. As a result of poor funding, failure of case finding and tracing would have raised the likelihood of acquiring an STD, and lack of access to treatment would have raised the cost of acquiring an STD. Hence, if anything, the decline in funding would have dampened—not caused—increases in risky sex. Lastly, even though decade effects and state-specific time trends may control for some omitted variables in regressions, it remains a possibility that other economic, social, and cultural changes contributed to increases in risky non-traditional sexual behavior. For example, the 1950s saw increased economic growth, huge increases in ownership of cars and televisions, suburbanization, the Civil Rights Movement, Cold War, the first issue of Playboy magazine, and the opening of Disneyland (Marling, 1994; Pomerance, 2005; Young & Young, 2004).

DISCUSSION All in all, the evidence suggests that the era of modern sexuality originated in the mid to late 1950s. Risky non-traditional sexual behaviors—as measured by the gonorrhea rate, illegitimate birth ratio, and teen birth share—began to rise during this period. These trends

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appear to coincide with the collapse of the syphilis epidemic. Syphilis incidence reached an alltime low in 1957, and syphilis deaths fell rapidly during the 1940s and early 1950s. Regression analysis demonstrated that most measures of sexual behavior significantly increased immediately following the collapse of syphilis, and most measures were significantly associated with the syphilis death rate. Together, the findings support the hypothesis that a decrease in the cost of syphilis spurred an increase in risky non-traditional sex during the 1950s. For some time, scholars have debated the nature of the "sexual revolution" of the 1960s and 1970s. Although there is some evidence that young adults after the mid-1960s had first intercourse at younger ages, had more sexual partners, and married at older ages, many scholars emphasize that changes in sexual behavior were gradual and likely started much earlier than the 1960s (Allyn, 2000; Bolin & Whelehan, 2009; Laumann et al., 1994; McLaren, 1999; Michael et al., 1994; Rathus et al., 2005). To many, these trends are best described as "evolutionary," not "revolutionary." The evidence in the present study is not inconsistent with the existence of gradual trends in certain dimensions of sexual behavior over a long period of time. Nevertheless, the measures of sexual behavior examined in this paper exhibited dramatic increases from the mid to late 1950s. Though it may also have had evolutionary aspects, the findings point to the revolutionary character of this era. Intriguingly, the historical syphilis epidemic parallels the contemporary AIDS epidemic. Recent studies report that the development of highly active antiretroviral therapy (HAART) may have caused some men who have sex with men to be less concerned about contracting and transmitting HIV and therefore more likely to engage in sexual behaviors that raise HIV transmission (Jaffe et al., 2007; Katz et al., 2002; Lakdawalla, Sood, & Goldman, 2006; Wolitski et al., 2001). Such attitudinal changes may be due either to the belief that the per-contact

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probability of transmission is lower because of HAART or the belief that contracting HIV is no longer fearsome because HAART significantly extends the life expectancy of those infected with HIV. Thus, the advent of penicillin may have produced analogous effects on sexual behavior as the advent of HAART, which implies that the spread of HIV may have been facilitated by the collapse of syphilis. Moreover, both cases illustrate the basic principle that behavior affects the cost of disease and also that the cost of disease affects behavior. What results is an equilibrium of this interplay. A number of disciplines have appealed implicitly to this principle, and economics has adopted it explicitly (Ahituv, Hotz, & Philipson, 1996; Francis, 2008; Kremer, 1996). Although the hypothesis in this study was first suggested by some physicians and public health officials in the 1950s, it was cast in strongly moralistic terms at the time (Brandt, 1985, Brown, 2006; Martinez, 1961; Plotke, 1955). For example, a Spanish physician, Eduardo Martinez Alonso, wrote about the effects of penicillin saying: “The wages of sin are now negligible. One can almost sin with impunity, since the sting of sinning has been removed” (Martinez, 1961, page 165). The phrase “wages of sin” refers to Romans 6:23 and to the traditional Judeo-Christian notion that those who choose behaviors abhorrent to God may be punished by God with disease. Many people in the 1950s equated non-traditional sex with sin and syphilis death with punishment. Essentially the same happened in the 1980s, when homosexuality was equated with sin and AIDS death with punishment (Brandt, 1985). Hence, it is reasonable that some scholars and commentators would distance themselves from the “cost” hypothesis because they were deeply concerned by the ethical and health implications of equating disease with sin. This study sympathizes with the view that a moralistic approach is counterproductive but highlights the merits of the idea that individuals may respond to the cost of disease.

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It is important to recognize the limitations of this study. It was challenging to measure sexual behaviors during the period of interest. Nationally representative survey data were extremely scarce. Instead, the study had to rely on contemporaneously reported vital statistics. Also, the study was unable to confirm or reject alternative hypotheses, because it was even more difficult to measure use of contraceptive technology, social attitudes toward sex, and moral values during the period. Finally, given that penicillin treatment diffused so rapidly, variation in syphilis incidence and deaths across states was rather low, frustrating efforts to estimate state panel regressions.

Conclusions This study makes several contributions. First, it casts the emergence of modern sexuality in a new light. The evidence supports the notion that the discovery of penicillin significantly decreased the cost of syphilis, which in turn increased risky non-traditional sex during the mid to late 1950s. Second, the study illustrates that medical progress can result in unintended changes in behavior that partially counteract the expected outcomes, suggesting that policy makers take into consideration behavioral responses to changes in the cost of disease. Third, the possible relationship between the collapse of syphilis and the rise of HIV implies that optimal health policy strategy is holistic and longsighted. To focus exclusively on the defeat of one disease can set the stage for the onset of another if preemptive measures are not taken. Lastly, the study provides another reason why traditional moralistic views of disease, which equate disease with punishment and certain behaviors with sin, are unhelpful. The case of syphilis shows that the relationship between behavior and disease is neither simple nor absolute. Behavior may affect

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the cost of disease, and also the cost of disease may affect behavior. This may inspire some to reconsider assumptions about disease, behavior, and sin.

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Liu, P. F., Euerle, B., & Chandrasekar, P. H. (2011). Syphilis. Retrieved from http://emedicine.medscape.com/article/229461 Lundberg, S., & Plotnick, R. D. (1990). Effects of state welfare, abortion and family-planning policies on premarital childbearing among white adolescents. Family Planning Perspectives, 22, 246-275. Marling, K. A. (1994). As seen on TV: The visual culture of everyday life in the 1950s. Cambridge: Harvard University Press. Marshall, R., & Donovan, C. (1991). Blessed are the barren: The social policy of Planned Parenthood. San Francisco, CA: Ignatius Press. Martinez, E. A. (1961). Adventures of a doctor. London, England: Robert Hale Limited. May, E. T. (2010). America and the pill: A history of promise, peril, and liberation. New York, NY: Basic Books. McLaren, A. (1999). Twentieth-century sexuality: A history. Oxford: Blackwell Publishers. Michael, R. T., Gagnon, J. H., Laumann, E. O., & Kolata, G. (1994). Sex in America. Boston: Little, Brown and Company. Paton, D. (2002). The economics of family planning and underage conceptions. Journal of Health Economics, 21, 207-225. Plotke, F. (1955). Modern trends in the management and control of syphilis. American Journal of Nursing, 55, 1482-1484. Pomerance, M. (2005). American cinema of the 1950s. Oxford: Berg Porter, R. S., & Kaplan, J. L., eds. (2011). Syphilis. Retrieved from http://www.merckmanuals.com/professional/print/infectious_diseases/sexually_transmitted_ diseases_std/syphilis.html

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Raine, T. R., Harper, C. C., Rocca, C. H., Fischer, R., Padian, N., Klausner, J. D., & Darney, P.D. (2005). Direct access to emergency contraception through pharmacies and effect on unintended pregnancy and STIs: A randomized controlled trial. JAMA, 293, 54-62. Rathus, S. A., Nevid, J. S., & Fichner-Rathus, L. (2005). Human sexuality in a world of diversity. Boston: Pearson Education, Inc. Santelli, J. S., Lindberg, L. D., Finer, L. B., & Singh, S. (2007). Explaining recent declines in adolescent pregnancy in the United States: The contribution of abstinence and improved contraceptive use. American Journal of Public Health, 97, 150-156. U.S. Census Bureau. (1937-1975). Statistical Abstract of the United States, 1937-1975. Retrieved from http://www.census.gov/compendia/statab/past_years.html U.S. Census Bureau. (2011). Population Estimates. Retrieved from http://www.census.gov/popest/archives/1980s/80s_st_totals.html U.S. Department of Health and Human Services. (2000). National Survey of Family Growth, Cycle III, 1982. Ann Arbor, MI: Interuniversity Consortium for Political and Social Research. U.S. Public Health Service. (1963). VD statistical letter supplement. Washington, DC: U.S. Government Printing Office. Wolitski, R. J., Valdiserri, R. O., Denning, P. H., & Levine, W. C. (2001). Are we headed for a resurgence of the HIV epidemic among men who have sex with men? American Journal of Public Health, 91, 883-888. Young, W. H., & Young, N. K. (2004). The 1950s. Westport, CT: Greenwood Press.

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  Table 1 Syphilis deaths in 1939 and AIDS deaths in 1995 Death rate (number per 100,000 persons)

Death share (% of deaths of any cause)

Syphilis 1939

AIDS 1995

Syphilis 1939

AIDS 1995

Total White males White females Black males Black females

15.0 15.5 5.2 72.5 35.6

16.2 20.9 2.5 80.2 24.0

1.4% 1.4% 0.6% 5.2% 3.0%

1.9% 2.3% 0.3% 8.4% 3.2%

Ages 25-64 Total White males White females Black males Black females

21.4 22.0 6.6 121.7 52.8

30.0 38.4 4.5 164.3 44.5

2.5% 2.4% 1.0% 7.4% 3.7%

7.7% 8.2% 1.8% 17.8% 9.4%

All ages

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  Table 2 Estimated risk of syphilis for a sexually-active adult in the mid-1940s

  

Parameters Number of sexual encounters with randomly-selected partner Population of 15-40 year olds in U.S., 1944 a Number of syphilis deaths in U.S., 1937-1944 b Average ratio of new infections to deaths (before 1944) c Per-contact probability of syphilis transmission d Percentage of untreated infected people who develop tertiary stage syphilis d Percentage of people with tertiary syphilis who die of the disease e

10 58,601,551 129,753 4.7 30% 33% 20%

Estimates Number of recently infected people as of mid-1940s (new infections, 1937-1944) Probability that randomly-selected partner infected with syphilis Probability of syphilis death if partner infected

610,973 1.04% 6.41%

Note: The number of recently infected people was 129,753 x 4.7087; the probability partner infected with syphilis was 610,973/58,601,551; and the probability of syphilis death if partner infected was 0.33 x 0.20 x (1-(1-0.30)^10). Parameter values were based on (a) U.S. Census Bureau, 2011; (b) CDC, 1937-1975; (c) U.S. Public Health Service, 1963; (d) Porter & Kaplan, 2011; (e) Liu, Euerle, & Chandrasekar, 2010.

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  Table 3 Effects of collapse of syphilis, 1937-1975 Dependent Variable

Number of years since collapse of syphilis 3 or fewer 4-7 8-11 12-15 16 or more Sample size State fixed effects Controls for decade

Gonorrhea incidence rate (1) (2)

Illegitimate birth ratio (whites) (3) (4)

Illegitimate birth ratio (non-whites) (5) (6)

-0.29 ** -0.15 * 0.16 * 0.64 ** 0.98 **

4.14 ** 12.02 ** 26.48 ** 36.40 ** 46.31 **

46.74 ** 79.17 ** 138.43 ** 212.47 ** 273.39 **

23.80 ** 47.98 ** 105.80 ** 146.57 ** 194.77 **

1618 Yes No

1618 Yes Yes

1767 Yes No

-0.15 ** -0.09 0.19 ** 0.51 ** 0.75 ** 1767 Yes Yes

1624 Yes No

3.19 ** 8.69 ** 22.87 ** 30.74 ** 39.84 ** 1624 Yes Yes

Teen birth share (whites) (7) (8) 1.63 ** 2.80 ** 4.12 ** 4.89 ** 5.48 ** 1944 Yes No

1.32 ** 2.05 ** 3.28 ** 3.63 ** 3.92 ** 1944 Yes Yes

Teen birth share (non-whites) (9) (10) -1.81 ** -0.43 5.55 ** 10.12 ** 11.16 ** 1944 Yes No

0.77 ** 2.66 ** 8.68 ** 12.53 ** 13.15 ** 1944 Yes Yes

* p<.10; ** p<.05 Note: Collapse of syphilis was identified as the year when the three-year moving average of new syphilis cases reached a minimum. Gonorrhea incidence rate spanned 1941-1975 and was logged. Data on the illegitimate birth ratio were missing for some states in some years. All specifications were weighted by state population share. Robust standard errors were adjusted for clustering on states.

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  Table 4 Effects of syphilis death rate, 1937-1975 Independent Variable: Syphilis death rate       Dependent Variable Gonorrhea incidence rate Illegitimate birth ratio (whites) Illegitimate birth ratio (non-whites) Teen birth share (whites) Teen birth share (non-whites)

-0.18 ** -9.52 ** -58.55 ** -1.30 ** -2.19 **

-0.17 ** -7.30 ** -39.24 ** -0.60 ** -2.28 **

-0.09 ** -5.71 ** -23.43 ** -0.78 ** -2.57 **

State fixed effects Controls for decade State-specific year trends State-year controls

Yes No No No

Yes Yes No No

Yes Yes Yes No

  

-0.07 ** -1.33 ** -9.93 ** 0.11 * -0.87 ** Yes Yes Yes Yes

* p<.10; ** p<.05 Note: Gonorrhea incidence rate spanned 1941-1975. Gonorrhea incidence and syphilis death rates were logged. Data on the illegitimate birth ratio were missing for some states in some years. State-year controls included average real income per capita, average real expenditures per public school student, percentage with a college degree, marriage rate, and birth rate. All specifications were weighted by state population share. Robust standard errors were adjusted for clustering on states.

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Figure captions Fig. 1 Trends in sexual behavior. Gonorrhea rate was the number of new gonorrhea cases per 100,000 population; illegitimate birth ratio was the number of births to unmarried mothers per 1,000 live births (whites); and teen birth share was the percentage of live births to women age 19 or younger (whites). In order to plot the variables together, each of the variables was standardized to have a mean of zero and a SD of one. Mean and SD were 213.7 and 89.5, respectively, for the gonorrhea rate, 30.5 and 16.4 for the white illegitimate birth ratio, and 12.4 and 2.3 for the white teen birth share. 1941 was the earliest year that the gonorrhea rate was available. Fig. 2 Trends in sexual behavior (non-whites). Illegitimate birth ratio was the number of births to unmarried mothers per 1,000 live births (non-whites); and teen birth share was the percentage of live births to women age 19 or younger (non-whites). In order to plot the variables together, each of the variables was standardized to have a mean of zero and a SD of one. Mean and SD were 232.2 and 92.2 for the non-white illegitimate birth ratio, and 23.4 and 4.8 for the non-white teen birth share. Fig. 3 Collapse of syphilis, rise of contraception. Syphilis rate was the number of new syphilis cases per 100,000 population; syphilis death rate was the number of deaths attributable to syphilis per 100,000 population; family planning services was the percentage of unmarried women age 16 to 30 who ever had received family planning services; and abortion ratio was the number of abortions per 1,000 live births. In order to plot the variables together, each of the variables was standardized to have a mean of zero and a SD of one. Mean and SD were 21.6 and 21.9, respectively, for the syphilis rate, 4.7 and 4.8 for the syphilis death rate, 21.4 and 15.2 for family planning services, and 179.8 and 78.5 for the abortion ratio. 1941 was the earliest year that the syphilis rate was available. Fig. 4 Permissive attitudes toward sex by birth year. Permissiveness toward premarital sex was the proportion of participants who reported that sexual relations before marriage between a man and woman is wrong only sometimes or not wrong at all. Permissiveness toward abortion was the proportion of participants who reported that it should be possible for a pregnant woman to obtain a legal abortion if the woman wants it for any reason. Permissiveness toward same-sex sex was the proportion of participants who reported that sexual relations between two adults of the same sex is wrong only sometimes or not wrong at all. Calculated from General Social Surveys, 1973-2008 (Davis, Smith, & Marsden, 2010). Fig. 5 Religious behavior by birth year. "Have religious affiliation" was the proportion of participants who reported that they had a religious preference other than "none." "Attend at least annually" was the proportion of participants who reported that they attend religious services once a year or more. "Attend at least monthly" was the proportion of participants who reported that they attend religious services once a month or more. Calculated from General Social Surveys, 1973-2008 (Davis, Smith, & Marsden, 2010).

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