Understanding Life Expectancy

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Life expectancy refers to the average number of years an individual is expected to live. It can be affected by that person’s family and health history, genetics, environment, lifestyle factors such as diet, and even age and sex.

Life expectancy also can refer to the average number of years a group of people or a specific population is expected to live. Whether referring to an individual or a group, the most common measure of life expectancy is life expectancy at birth, which is the age to which a newborn is expected to live given age-specific death rates at the time of their birth.

According to the Centers for Disease Control and Prevention (CDC), the life expectancy at birth of a person born in 2018 is 78.7 years. However, as mentioned, life expectancy can be affected by certain factors. One example is the assigned sex at birth. The life expectancy at birth of a male baby born in 2018 is 76.2 years, while that of a female newborn is 81.2 years.

Changes in Life Expectancy

Life expectancy can change. Deaths at young ages impact life expectancy averages much more than deaths at older ages. Young deaths impact life expectancy at birth statistics.

Each year a person lives means they have survived multiple potential causes of death. This means that life expectancy actually can increase with age.

For instance, the life expectancy at birth of someone born in 1943 was about 68 years. If that person survived to 65 (in 2008), they could expect to live another 18.8 years, meaning their life expectancy was no longer the same as it was at birth—it was 8.6 years longer than the life expectancy of people born in 2008—86.8 years.

If that person lived to 75 (in 2018), their life expectancy increased to 87.3—8.6 years longer than the average child born in 2018.

Beating the Odds

All the statistics in the world ultimately can’t predict precisely how long a person will live. Although there are many factors that contribute to life expectancy that cannot be altered—again, sex, race, genetics—there are plenty of things they can do.

Longevity can be affected by measures to preserve health, for example—eating nutritious food, maintaining a healthy weight, not smoking, staying physically and mentally active, and engaging in social opportunities.

As far as drinking alcohol, the data are mixed. It’s clear that drinking to excess negatively affects health, but moderate drinking might actually be protective.

Taking measures to stay safe can also play a role. Examples include wearing a seatbelt in a car or a helmet and other safety gear when engaging in sports.

2 Sources
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  1. Centers for Disease Control and Prevention, National Center for Health Statistics. Health, United States, 2019.

  2. Centers for Disease Control and Prevention, National Center for Health Statistics. Health, United States, 2019. Table 4. Life expectancy at birth, age 65, and age 75, by sex, race, and Hispanic origin: United States, selected years 1900–2018.

By Mark Stibich, PhD
Mark Stibich, PhD, FIDSA, is a behavior change expert with experience helping individuals make lasting lifestyle improvements.