Life expectancy in the United Kingdom was below 39 years in the year 1765, and over the course of the next two and a half centuries, it is expected to have increased by more than double, to 81.1 by the year 2020. Although life expectancy has generally increased throughout the UK's history, there were several times where the rate deviated from its previous trajectory. These changes were the result of smallpox epidemics in the late eighteenth and early nineteenth centuries, new sanitary and medical advancements throughout time (such as compulsory vaccination), and the First world War and Spanish Flu epidemic in the 1910s.

In 1800, the average child born in the region of present-day Turkey was expect to live to the age of 35. This figure would see little change for most of the 19th century, rising to just 36 years by the beginning of the 20th century. However, Turkey’s life expectancy would fall greatly with the beginning of the First World War in 1914, as both extensive wartime casualties and an organized campaign of mass execution and deportation of the Ottoman Empire's non-Turkish populations would result in the deaths of approximately three million people; the victims of the respective Armenian, Assyrian and Greek genocides are thought to make up over half of these deaths.

Following the collapse of the Ottoman Empire and establishment of the Turkish Republic in 1923, life expectancy in Turkey would begin to recover somewhat, but would proceed to fall again in the late 1930s, as the Great Depression and the Second World War would cause significant economic harm to the country, despite Turkey’s neutrality for much of the conflict. However, the 1950s would see Turkey’s population begin to grow rapidly, as the republic would begin to rapidly modernize both the country’s healthcare and economy, and mass immunization programs would lead to a sharp drop in child mortality. As a result, Turkey’s life expectancy would rise to over 68 years by 2000, with a slight increase beginning in the early 2000s after healthcare reforms in the country established universal healthcare in the country. As a result, in 2020, it is estimated that the average person born in Turkey will live to an age of just over 77 years.

Life expectancy in Canada was just below forty in the year 1800, and over the course of the next 220 years, it is expected to have increased by more than double to 82.2 by the year 2020. Throughout this time, life expectancy in Canada progressed at a steady rate, with the most noticeable changes coming during the interwar period, where the rate of increase was affected by the Spanish Flu epidemic and both World Wars.

Life expectancy in Japan was 36.4 in the year 1860, and over the course of the next 160 years, it is expected to have increased to 84.4, which is the second highest in the world (after Monaco). Although life expectancy has generally increased throughout Japan's history, there were several times where the rate deviated from its previous trajectory. These changes were a result of the Spanish Flu in the 1910s, the Second World War in the 1940s, and the sharp increase was due to the high rate of industrialization and economic prosperity in Japan, in the mid-twentieth century.

Life expectancy in France was below thirty in the late 1700s, but over the course of the next two and a half centuries it is expected to reach 82.5 by the year 2020. Although life expectancy has generally increased throughout France's history, there were several times where the rate deviated from its previous trajectory. The most noticeable changes were because of smallpox and influenza epidemics in the 1700s, medical advancements (such as vaccination and pasteurization) saw life expectancy increase in the 1800s, and then both World Wars and the epidemics that followed caused brief drops in the first half of the twentieth century.

Life expectancy in Finland was 35.3 in the year 1765, and over the course of the next 255 years, it is expected to have increased by over double this, to 81.6 years by 2020. Although life expectancy has generally increased throughout Finland's history, it fluctuated greatly between 1765 and 1875, in the 1910s because of the Spanish Flu epidemic that swept across the world and the Finnish Civil War, and again during the Second World War in the 1930s and 40s.

Show BMI distributions, including mean, standard deviation (SDs), median, and 5th and 95th percentile of mothers at age 7 and 13 years and their sons and daughters at age 7 years by eight intervals of children’s birth year.

In the century between 1920 and 2020, life expectancy more than doubled in Albania, increasing from approximately 32 years in 1920, to 78 years in 2020. Between 1925 and 1930, life expectancy stagnated, due to political instability and poor economic opportunities, although it then increased well into the late 1930s. It was during the Second World War when life expectancy decreased, as Albania was annexed first by Italy, and later by Germany. An estimated 30,000 Albanians perished as a direct result of the war, and life expectancy fell by almost three years in this five year period. In the 1950s, Albania's pre-war trajectory continued, and life expectancy rose to above 50 years in 1950, and has gradually increased to over 78 years today. There was a slight decrease in life expectancy in the early 1990s, as the communist system in Eastern Europe collapsed, however Albania's life expectancy has since increased well above the global average.

Life expectancy in Poland was 35.9 in the year 1885, and over the course of the next 135 years, it is expected to have increased to 78.5 by the year 2020. Although life expectancy has generally increased throughout Poland's history, the most noticeable decline came in the 1940s as a result of the Second World War and Holocaust, which caused Poland's population to decline by about 17 percent, which was more than any other country.

At the beginning of the 1840s, life expectancy from birth in Ireland was just over 38 years. However, this figure would see a dramatic decline with the beginning of the Great Famine in 1845, and dropped below 21 years in the second half of the decade (in 1849 alone, life expectancy fell to just 14 years). The famine came as a result of a Europe-wide potato blight, which had a disproportionally devastating impact on the Irish population due to the dependency on potatoes (particularly in the south and east), and the prevalence of a single variety of potato on the island that allowed the blight to spread faster than in other areas of Europe. Additionally, authorities forcefully redirected much of the country's surplus grain to the British mainland, which exacerbated the situation. Within five years, mass starvation would contribute to the deaths of over one million people on the island, while a further one million would emigrate; this also created a legacy of emigration from Ireland, which saw the population continue to fall until the mid-1900s, and the total population of the island is still well below its pre-famine level of 8.5 million people.

Following the end of the Great Famine, life expectancy would begin to gradually increase in Ireland, as post-famine reforms would see improvements in the living standards of the country’s peasantry, most notably the Land Wars, a largely successful series of strikes, boycotts and protests aimed at reform of the country's agricultural land distribution, which began in the 1870s and lasted into the 20th century. As these reforms were implemented, life expectancy in Ireland would rise to more than fifty years by the turn of the century. While this rise would slow somewhat in the 1910s, due to the large number of Irish soldiers who fought in the First World War and the Spanish Flu pandemic, as well as the period of civil unrest leading up to the island's partition in 1921, life expectancy in Ireland would rise greatly in the 20th century. In the second half of the 20th century, Ireland's healthcare system and living standards developed similarly to the rest of Western Europe, and today, it is often ranks among the top countries globally in terms of human development, GDP and quality of healthcare. With these developments, the increase in life expectancy from birth in Ireland was relatively constant in the first century of independence, and in 2020 is estimated to be 82 years.

Life expectancy in Australia was just below 35 in the year 1870, and over the course of the next 150 years, it is expected to have increased to 83.2 by the year 2020. Although life expectancy has generally increased throughout Australia's history, there were several times where the rate deviated from its previous trajectory. the most noticeable changes were between 1890 and 1920. This period included Australia's Independence movement, the implementation of the 'White Australia' policy, the First World War and Spanish Flu epidemic, all of which impacted the demographics of Australia.

Life expectancy in New Zealand was just over 34 in the year 1870, and over the course of the next 150 years, it is expected to have increased to just over 82 by the year 2020. Although life expectancy has generally increased along a gradual curve throughout New Zealand's history, there was a slight dip in the late 1910s, as a result of the First World War and following influenza epidemic. Apart from this, there were no anomalies that reduced life expectancy throughout this 150 year period.

Life expectancy in Spain was below thirty in the year 1880, and over the course of the next 140 years, it is expected to have increased to 83.4 by the year 2020. Although life expectancy has generally increased throughout Spain's history, there were several times where the rate deviated from its previous trajectory. The most notable changes were a result of the global influenza epidemic of the 1910s, (called the 'Spanish Flu' as it received more press coverage in neutral Spain, during the First World War) and the Spanish Civil War two decades later.

Life expectancy in the Netherlands was just under forty in the year 1850, and over the course of the next 170 years, it is expected to have increased to more than 82 in 2020. Although life expectancy has generally increased throughout the Netherlands' history, there were several times where the rate deviated from its previous trajectory. The most noticeable changes were a result of the Spanish Flu pandemic of the late-1910s, and the Second World War.

In 1880, the average person born in the area of modern-day South Korea could expect to live to just under the age of 26, a figure which would remain below thirty until the 1920s. Life expectancy would fall to its lowest level of just 24 years in 1920, however, as the 1918 Spanish Flu epidemic would spread through the country, resulting in an estimated 200,000 deaths across the Korean peninsula. Life expectancy would begin to rise in the 1920s, however, as development programs by the Japanese colonial administration would see economic growth and access to healthcare improve greatly in the region. The 1940s and 1950s would see a slowing, then a reversal to this growth though, as the final years of the Second World War, and later the 1950 Korean War, would see significant destruction and fatalities in the country.

Following the end of the Korean War with the 1953 armistice, life expectancy would begin to climb again in the newly-established South Korea, as the country would begin to rapidly modernize and improve access to healthcare and nutrition, raising standards of living and cutting child mortality rates throughout the country. As a result, life expectancy would rise from just under 47 years in 1950, to over 75 years by the turn of the century. This rise in life expectancy has continued steadily into the 21st century, and as a result, in 2020, it is estimated that the average person born in South Korea will live to just under the age of 83 years, one of the highest life expectancies in the world.

Life expectancy in Austria was below 35 in the year 1870, and over the course of the next 150 years, it is expected to have increased to over 81 years by 2020. Although life expectancy has generally increased throughout Austria's history, there were several times where the rate deviated from its previous trajectory. Most noticeably, these were caused by both World Wars, and the Spanish Flu epidemic during and after WWI.

Life expectancy in Portugal was 35.6 years in 1915, and over the course of the next century, it is expected to have increased by more than double, to 81.8 in 2020. Although life expectancy has generally increased throughout Portugal's history, there was a decline in the 1910s, as a result of the worldwide influenza pandemic, that is now known as the Spanish Flu. From this point onwards, Portugal's life expectancy increased at every five year interval.

The child mortality rate in the United States, for children under the age of five, was 462.9 deaths per thousand births in 1800. This means that for every thousand babies born in 1800, over 46 percent did not make it to their fifth birthday. Over the course of the next 220 years, this number has dropped drastically, and the rate has dropped to its lowest point ever in 2020 where it is just seven deaths per thousand births. Although the child mortality rate has decreased greatly over this 220 year period, there were two occasions where it increased; in the 1870s, as a result of the fourth cholera pandemic, smallpox outbreaks, and yellow fever, and in the late 1910s, due to the Spanish Flu pandemic.

The Second World War had a profound impact on gender ratios within the Soviet Union's population, and its effect on different age groups varied greatly. The Soviet population structure had already been shaped heavily by the First World War, the Russian Revolution, and the famines of the early 1920s and early 1930s. The impact of these events on mortality and fertility meant that, in 1941, the generations whose births corresponded with these events had a lower population than would be expected on a typical population model. For example, in 1941, those aged between 5 and 9 had a significantly lower population than those aged 10 to 14, due to the effects of the Soviet famine of 1932-1933. Additionally, women outnumbered men in all age groups except the very youngest, due to the disproportionate effect of conflict and infant mortality on male populations. Impact of WWII In order to observe the impact of the war, one must compare populations of specific age groups in 1941 with the following age group in 1946. For men of "fighting age" in 1941, i.e. those aged between 15 and 44, these populations experience the most substantial decrease over the course of the war. For example, there are 5.6 million men aged 15-19 in 1941, but just 3.5 million aged 20-24 in 1946, giving a decrease of 38 percent. This decrease of almost forty percent can be observed until the 45-49 group, where the difference is 25 percent. Additionally, women aged between 15 and 34 saw a disproportionate decrease in their populations over this period, as many enlisted in the army and took an active part in the conflict, most notably as medics, snipers, and pilots.

The war's impact on fertility and child mortality meant that, in 1946, the total population under four years old was less than half its size in 1941. Generally, variations between age groups then fluctuated in line with pre-war patterns, however the overall ratio of women to men increased further after the war. For all age groups over 20 years, the number of men decreased between these years, whereas all women's age groups over 30 years saw an increase; this meant that, despite the war, women over 30 had a higher life expectancy in 1946.

The child mortality rate in the United Kingdom, for children under the age of five, was 329 deaths per thousand births in 1800. This means that approximately one in every three children born in 1800 did not make it to their fifth birthday. Over the course of the next 220 years, this number has dropped drastically, particularly in the first half of the twentieth century, and the rate has dropped to its lowest point ever in 2020 where it is just four deaths per thousand births.