The Gender Gap in Mortality
Table 1 provides an historical overview of the gender gap in U.S. mortality from 1900 to 2003. The most recent data show that the gender gap in life expectancy is 5.3 years, marking the lowest point in more than 50 years. The gap is largest when measured at birth and shrinks dramatically with age. In other words, if men live to the age of 65, and especially 75, their life expectancies approach that of women of the same age. The gender gap shrinks with age because men are more likely to die at younger ages from a variety of causes (e.g., heart disease, cirrhosis of the liver, homicide, suicide), and mortality rates between the sexes equalize in the later years.
Two points are especially noteworthy in Table 1 . First, regardless of when life expectancy is measured (at birth or later ages), women outlive men. Second, the size of women's advantage over men has been steadily shrinking since the 1970s. Thus the questions remain: What contributes to the gender gap in mortality and what explains the narrowing of the gap over the past few decades? We will focus on the first question (why men live shorter lives than women) before turning to the second (why the gender gap has been decreasing).
Leading explanations for women's advantaged mortality profile can be classified broadly into three categories: biological, social structural, and behavioural. From a biological standpoint, it appears that women are offered some protection against mortality. Studies suggest that estrogen helps protect women against heart disease by reducing circulatory levels of harmful cholesterol, whereas testosterone increases low-density lipoprotein. Further, women have stronger immune systems, in part because testosterone causes immunosuppression. However, biology alone can not explain gender difference in mortality, especially since this relationship differs substantially over time and across nations. Thus, most contemporary research focuses on social, structural, and behavioural factors in attempting to explain the gender gap in mortality. Indeed, a number of these factors were very influential in the widening mortality divide between men and women during the first three-quarters of the 20th century.
First, wealthy nations such as the United States experienced a substantial drop in female mortality at young ages, particularly childbearing-related deaths, due to improvement in prenatal and obstetric care. Men, however, continue to experience substantial premature death during the adolescent, young adult, and middle-aged years. Today, for most major causes of death (12 of the top 15 causes of death in 2004), age-adjusted death rates are higher among men than women.
Second, the social and economic status of women relative to men has been rising in industrialized nations for some time, and women's health has benefited from these improvements. This also has important implications for the gender gap in mortality because as women's status continues to rise, the mortality gap may start widening again. Substantial evidence documents the health risks associated with aspects of socioeconomic position, including low education and poverty. Yet, despite improvements over time, the socioeconomic status of women remains below that of men. Women in U.S. society are more likely than men to work part-time, participate in unwaged labour, and receive unequal wages, all of which contribute to their lower socioeconomic position and depress their health. And, it appears that the gender gap in life expectancy would be even bigger if women were more economically equal to men.
Third, gender differences in health behaviours make an important contribution to male disadvantage in mortality. Some behaviours favour men (e.g., exercise), but most do not. Adult women under the age of 65 report more doctor visits than men, with the gender gap widest among persons aged 18-44, mostly because of medical care associated with reproduction. In addition, men drink alcohol more, and more often, than women,[10,11] and are more than twice as likely to die from chronic liver disease and cirrhosis. Men are also two to four times more likely than women to die prematurely from unintentional injury, homicide, and suicide. Perhaps most importantly, more men than women smoke cigarettes, although this difference is essentially nonexistent at the youngest ages, which shows that smoking rates are equalizing in the youngest age cohorts.[12,13] Smoking is particularly significant in this instance because estimates suggest that rising rates of smoking among men, relative to women, accounted for 75% of the increase in the gender gap in mortality between 1910 and 1962. Current estimates suggest that smoking accounts for 25% of the overall sex mortality difference, and much more when cancer and respiratory disease mortality are separately considered.
The last explanation for the gender gap in mortality reviewed above (smoking) brings us to the second question addressed in this article--why has the size of the gender gap been shrinking in several nations since the 1970s? Here the evidence is incredibly convincing that smoking is the key factor determining the size of the gender gap in mortality across high-income nations.[4,15,16] In the United States, men have been reducing smoking faster than women. In the mid 1960s there was an 18% differential in smoking (52% of men and 34% of women were smokers), and by 2005 this had shrunk to a 5.8% difference, with 23.9% of men and 18.1% of women reporting that they currently smoke.[17,18] Similar trends have been observed in other high-income nations, with strong evidence indicating that the diffusion of cigarette smoking between men and women is what determines whether the gender gap in mortality is narrowing, stable, or still widening. However, it is important to note that while changing rates of smoking between men and women have been overwhelmingly responsible for the shrinking mortality gap in the United States and other countries, smoking is not the sole cause of gender differences in mortality. Thus, the female advantage in mortality has fallen in many nations during the last few decades because of the adoption of smoking by many women, but women continue to retain a mortality advantage--largely because their mortality advantage over men continues to increase for causes of death unrelated to smoking (e.g., suicide and homicide).
Looking toward the future, many wonder whether the mortality gap will completely close. This seems unlikely, at least in the foreseeable future. In high-income nations where the gap is stable or still widening, closure is a long way off. In nations where the gap is narrowing, forecasts suggest that the rate of closure will slow, but will continue to at least 2020. Why is this the case? As discussed above, smoking has played a major role in the shrinking of the gender gap, but its contribution is in decline because smoking rates between men and women are nearly equal in countries such as the United States. This means that nonsmoking causes of the gap will become more relevant over time. And, given the importance of social and economic factors, it suggests that the gap could widen again in the future if women continue to make gains in society relative to men. One exception may be that if women are approaching a maximum limit on life expectancy, their mortality may slow to the point that men do catch up. In the end, only one thing is clear: the gender gap in mortality will remain in-flux for quite some time due to the continual shifts in the social, economic, and behavioural dynamics that determine health and longevity for both women and men.
Geriatrics and Aging. 2007;10(3):182-191. © 2007 1453987 Ontario, Ltd.
Cite this: Why Men Die Younger than Women - Medscape - Mar 01, 2007.