The fertility rate of a country is the average number of children that women from that country will have throughout their reproductive years. In the United States in 1800, the average woman of childbearing age would have seven children over the course of their lifetime. As factors such as technology, hygiene, medicine and education improved, women were having fewer children than before, reaching just two children per woman in 1940. This changed quite dramatically in the aftermath of the Second World War, rising sharply to over 3.5 children per woman in 1960 (children born between 1946 and 1964 are nowadays known as the 'Baby Boomer' generation, and they make up roughly twenty percent of todays US population). Due to the end of the baby boom and increased access to contraception, fertility reached it's lowest point in the US in 1980, where it was just 1.77. It did however rise to over two children per woman between 1995 and 2010, although it is expected to drop again by 2020, to just 1.78.

In Germany, the crude birth rate in 1800 was 38 live births per thousand people, meaning that 3.8 percent of the population had been born in that year. In the nineteenth century, Germany's crude birth rate fluctuated between 34 and 40 births per thousand people. Since the turn of the twentieth century however, the crude birth rate has been in decline, although there were a few periods where it did increase. These increases took place during periods of economic recovery, after both world wars, and after the Great Depression. The largest period of increase was after the Second World War, and lasted until the late 1960s, before decreasing to 10.3 in 1980, where it then plateaus between eight and eleven, and it is expected to be 9.4 births per thousand people in 2020.

The fertility rate of a country is the average number of children that women from that country would have throughout their reproductive years. In the United Kingdom in 1800, the average woman of childbearing age would have five children over the course of their lifetime. Over the next 35 years the fertility rate was quite sporadic, rising to over 5.5 in the 1810s and 1820s, then dropping to 4.9 by 1835. This was during and after the Napoleonic Wars and the War of 1812 with the US, which was a time of increased industrialization, economic depression and high unemployment after the war. As things became more stable, and the 'Pax Britannica' (a period of relative, international peace and economic prosperity for the British Empire) came into full effect, the fertility rate plateaued until 1880, before dropping gradually until the First World War. The fertility rate then jumped from 2.6 to 3.1 children per woman between 1915 and 1920, as many men returned from the war. It then resumed it's previous trajectory in the interwar years, before increasing yet again after the war (albeit, for a much longer time than after WWI), in what is known as the 'Baby Boom'. Like the US, the Baby Boom lasted until around 1980, where it then fell to 1.7 children per woman, and it has remained around this number (between 1.66 and 1.87) since then.

This is the code replication archive for the paper, "The COVID-19 Baby Bump in the United States," published in the Proceedings of the National Academy of Sciences. The underlying natality microdata are restricted, so this archive contains only the code to replicate our analysis.We use natality microdata covering the universe of U.S. births for 2015-2021 and California births from 2015 through February 2023 to examine childbearing responses to the COVID-19 pandemic. We find that 60% of the 2020 decline in U.S. fertility rates was driven by sharp reductions in births to foreign-born mothers although births to this group comprised only 22% of all U.S. births in 2019. This decline started in January 2020. In contrast, the COVID-19 recession resulted in an overall “baby bump” among U.S.-born mothers which marked the first reversal in declining fertility rates since the Great Recession. Births to U.S.-born mothers fell by 31,000 in 2020 relative to a pre-pandemic trend but increased by 71,000 in 2021. The data for California suggest that U.S. births remained elevated through February 2023. The baby bump was most pronounced for first births and women under age 25, suggesting that the pandemic led some women to start families earlier. Above age 25, the baby bump was most pronounced for women ages 30-34 and women with a college education. The 2021-2022 baby bump is especially remarkable given the large declines in fertility rates that would have been projected by standard statistical models.

This map layer shows the prevalent generations that make up the population of the United States using multiple scales. As of 2018, the most predominant generations in the U.S. are Baby Boomers (born 1946-1964), Millennials (born 1981-1998), and Generation Z (born 1999-2016). Currently, Millennials are the most predominant population in the U.S.A generation represents a group of people who are born around the same time and experience world events and trends during the same stage of life through similar mediums (for example, online, television, print, or radio). Because of this, people born in the same generation are expected to have been exposed to similar values and developmental experiences, which may cause them to exhibit similar traits or behaviors over their lifetimes. Generations provide scientists and government officials the opportunity to measure public attitudes on important issues by people’s current position in life and document those differences across demographic groups and geographic regions. Generational cohorts also give researchers the ability to understand how different developmental experiences, such as technological, political, economic, and social changes, influence people’s opinions and personalities. Studying people in generational groups is significant because an individual’s age is a conventional predictor for understanding cultural and political gaps within the U.S. population.Though there is no exact equation to determine generational cutoff points, it is understood that we designate generational spans based on a 15- to 20-year gap. The only generational period officially designated by the U.S. Census Bureau is based on the surge of births after World War II in 1946 and a significant decline in birth rates after 1964 (Baby Boomers). From that point, generational gaps have been determined by significant political, economic, and social changes that define one’s formative years (for example, Generation Z is considered to be marked by children who were directly affected by the al Qaeda attacks of September 11, 2001).In this map layer, we visualize six active generations in the U.S., each marked by significant changes in American history:The Greatest Generation (born 1901-1924): Tom Brokaw’s 1998 book, The Greatest Generation, coined the term ‘the Greatest Generation” to describe Americans who lived through the Great Depression and later fought in WWII. This generation had significant job and education opportunities as the war ended and the postwar economic booms impacted America.The Silent Generation (born 1925-1945): The title “Silent Generation” originated from a 1951 essay published in Time magazine that proposed the idea that people born during this period were more cautious than their parents. Conflict from the Cold War and the potential for nuclear war led to widespread levels of discomfort and uncertainty throughout the generation.Baby Boomers (born 1946-1964): Baby Boomers were named after a significant increase in births after World War II. During this 20-year span, life was dramatically different for those born at the beginning of the generation than those born at the tail end of the generation. The first 10 years of Baby Boomers (Baby Boomers I) grew up in an era defined by the civil rights movement and the Vietnam War, in which a lot of this generation either fought in or protested against the war. Baby Boomers I tended to have great economic opportunities and were optimistic about the future of America. In contrast, the last 10 years of Baby Boomers (Baby Boomers II) had fewer job opportunities and available housing than their Boomer I counterparts. The effects of the Vietnam War and the Watergate scandal led a lot of second-wave boomers to lose trust in the American government. Generation X (born 1965-1980): The label “Generation X” comes from Douglas Coupland’s 1991 book, Generation X: Tales for An Accelerated Culture. This generation was notoriously exposed to more hands-off parenting, out-of-home childcare, and higher rates of divorce than other generations. As a result, many Gen X parents today are concerned about avoiding broken homes with their own kids.Millennials (born 1981-1998): During the adolescence of Millennials, America underwent a technological revolution with the emergence of the internet. Because of this, Millennials are generally characterized by older generations to be technologically savvy.Generation Z (born 1999-2016): Generation Z or “Zoomers” represent a generation raised on the internet and social media. Gen Z makes up the most ethnically diverse and largest generation in American history. Like Millennials, Gen Z is recognized by older generations to be very familiar with and/or addicted to technology.Questions to ask when you look at this mapDo you notice any trends with the predominant generations located in big cities? Suburbs? Rural areas?Where do you see big clusters of the same generation living in the same area?Which areas do you see the most diversity in generations?Look on the map for where you, your parents, aunts, uncles, and grandparents live. Do they live in areas where their generation is the most predominant?

Adjusted differences (Δ) and 95% Confidence Intervals are presented.*Birth and growth characteristics at age 10 years adjusted for maternal age and parity.†Adult anthropometrics and biomarkers adjusted for maternal age, maternal parity, and participant age at recruitment.BW: birth weight; BMI: body mass indexaPonderal index BW(g)/BL(cm)3×100.

This is the code replication archive for the paper, "The COVID-19 Baby Bump in the United States," forthcoming in the Proceedings of the National Academy of Sciences. The underlying natality microdata are restricted, so this archive contains only the code to replicate our analysis.We use natality microdata covering the universe of U.S. births for 2015-2021 and California births from 2015 through February 2023 to examine childbearing responses to the COVID-19 pandemic. We find that 60% of the 2020 decline in U.S. fertility rates was driven by sharp reductions in births to foreign-born mothers although births to this group comprised only 22% of all U.S. births in 2019. This decline started in January 2020. In contrast, the COVID-19 recession resulted in an overall “baby bump” among U.S.-born mothers which marked the first reversal in declining fertility rates since the Great Recession. Births to U.S.-born mothers fell by 31,000 in 2020 relative to a pre-pandemic trend but increased by 71,000 in 2021. The data for California suggest that U.S. births remained elevated through February 2023. The baby bump was most pronounced for first births and women under age 25, suggesting that the pandemic led some women to start families earlier. Above age 25, the baby bump was most pronounced for women ages 30-34 and women with a college education. The 2021-2022 baby bump is especially remarkable given the large declines in fertility rates that would have been projected by standard statistical models.

In Spain, the crude birth rate in 1850 was 36.3 live births per thousand people, meaning that 3.6 percent of the population had been born in that year. In the late nineteenth century, the crude birth rate of Spain fluctuated between 34 and 39 births per one thousand people. From 1905 until 1940, the numbers dropped gradually, from 35 to just under 22 births per thousand people, and it then remained around this number (between 20 and 22) until the late 1970s. In the latter stages of the twentieth century, the rate dropped again, to fewer than ten births per thousand. The crude birth rate rose slightly in the early 2000s, however the Great Recession led to many people migrating from Spain, and the rate decreased along with the population, and is expected to reach a record low of 8.5 in 2020.

In 1800, the total fertility rate in the region of present-day Latvia was 5.2 children per woman; meaning woman born in Latvia in that year could expect to have just over five children on average during the course of their reproductive years. Fertility in Latvia would decline steadily in the 19th century, primarily due to advancements in healthcare and declining child mortality rates, and also due to economic improvements in the years following the agricultural reforms of 1849, which would see a significant improvement in the living standards of the country’s peasantry. Fertility would decline faster in the 1930s and 1940s, due to the instability and devastation caused by the Second World War and Great Depression.

Following the end of the war, fertility would resume its steady decline until the 1970s and 1980s, when Latvian authorities promoted population growth and implemented financial incentives for mothers. However, with the demographic shifts following the dissolution of the Soviet Union in 1991, and economic downturn following the adoption of the market economy, women across most former-Soviet states were much more reluctant to have children in the 1990s. By the turn of the millennium, Latvia's fertility rate had fallen to just over one child per woman in 2000. While fertility has recovered somewhat following Latvia’s ascension to the European Union in 2004, total fertility remains below replacement level in the country, and in 2020, it is estimated that the average woman born in Latvia will have just over 1.7 children over the course of her reproductive years.

County fixed-effects regression estimates for the relationship between unemployment rate and LGA births in California, 2008–2011.

BackgroundData on the potential influence of macroeconomic recessions on maternal diseases during pregnancy are scarce. We aimed to assess potential change in prevalence of pregnancy-induced hypertensive disorders (preeclampsia and gestational hypertension) during the first years of the major national economic recession in Iceland, which started abruptly in October 2008.Methods and FindingsWomen whose pregnancies resulted in live singleton births in Iceland in 2005–2012 constituted the study population (N = 35,211). Data on pregnancy-induced hypertensive disorders were obtained from the Icelandic Medical Birth Register and use of antihypertensive drugs during pregnancy, including β-blockers and calcium channel blockers, from the Icelandic Medicines Register. With the pre-collapse period as reference, we used logistic regression analysis to assess change in pregnancy-induced hypertensive disorders and use of antihypertensives during the first four years after the economic collapse, adjusting for demographic and pregnancy characteristics, taking aggregate economic indicators into account. Compared with the pre-collapse period, we observed an increased prevalence of gestational hypertension in the first year following the economic collapse (2.4% vs. 3.9%; adjusted odds ratio [aOR] 1.47; 95 percent confidence interval [95%CI] 1.13–1.91) but not in the subsequent years. The association disappeared completely when we adjusted for aggregate unemployment rate (aOR 1.04; 95% CI 0.74–1.47). Similarly, there was an increase in prescription fills of β-blockers in the first year following the collapse (1.9% vs.3.1%; aOR 1.43; 95% CI 1.07–1.90), which disappeared after adjusting for aggregate unemployment rate (aOR 1.05; 95% CI 0.72–1.54). No changes were observed for preeclampsia or use of calcium channel blockers between the pre- and post-collapse periods.ConclusionsOur data suggest a transient increased risk of gestational hypertension and use of β-blockers among pregnant women in Iceland in the first and most severe year of the national economic recession.

County fixed-effects regression estimates for the relationship between unemployment rate and LGA births, 2008–2011, stratified by race/ethnicity.

County fixed-effects regression estimates for the relationship between unemployment rate and secondary outcomes, 2008–2011.

In 2024, the employment rate in China decreased to around 62.4 percent, from 62.8 percent in the previous year. China is the world’s most populous country and its rapid economic development over the past decades has profited greatly from its large labor market. While the overall working conditions for the Chinese people are improving, the actual size of the working-age population in China has been shrinking steadily in recent years. This is mainly due to a low birth rate in the country. Economic slowdown – impact on labor market After decades of rapid development, the world’s second largest economy now seems to have difficulties to boost its economy further. The GDP growth rate indicated a declining trend over the last decade and the number of employed people decreased for the first time since decades in 2015. Under the influence of the global economic downturn, the coronavirus pandemic, and the US-China tensions, many Chinese enterprises are having tough times, which leads to a recession in China’s labor market. Chances for better employment situation The long-lasting Sino-U.S. trade war has caused China great loss on its international trade sector, which has been driving China’s economic growth for decades. However, there is also a lot China could improve. First, the potential of domestic demands could be further developed and satisfied with high-quality products. Second, it’s a good timing to eliminate backward industries with low value added, and the high-tech and environment-friendly industries should be further promoted. In addition, China’s market could be more open to services, especially in the financial sector and IT services, to attract more foreign investors. Highly skilled talents should be better valued in the labor market. Efficient vocational education and further education could also help change the structure of China’s labor market.

Much of Argentina's modern society and culture is rooted in the Spanish Empire's colonization of the region in the 16th century, along with the influx of European migration to the country around the turn of the twentieth century. There are records of human presence in the region dating back to the paleolithic period (3.3 million to 9,650 BCE) and the Incan Empire is known to have extended into the region before Columbus' arrival in the Americas in 1492; however most of this culture and civilization was wiped out by Europeans in the 1500s. During Spanish colonization, the majority of Argentina was a part of the Viceroyalty of the Río de la Plata (which also included territories in modern-day Chile, Bolivia, Paraguay and Uruguay) and was still economically bound to the Spanish crown. With a population of just 0.5 million in 1800, a combination of mass migration (particularly from Southern Europe) and high birth rates have helped Argentina's population grow above 45 million over the past two centuries.

Independence, Immigration and the Gold rush The age of enlightenment and revolutions in Europe inspired a longing in the region for independence, and Napoleon's invasion of Spain in 1808 was the catalyst for the Spanish Empire's downfall in the Americas, with Argentinian independence declared in 1816. The Spanish military was then defeated in mid 1800s, but for the majority of the next century there was little political or economic stability in the region, with several small-scale civil wars between the different Argentinian states. Starting with the government of Julio Argentino Roca in 1880, ten consecutive federal governments actively pursued a liberal economic policy which led to a massive wave of state-promoted European immigration; so much so that the number of migrants received by Argentina in that period was second only to the United States worldwide. This immigration led to the rejuvenation and reinvention of Argentinian society and economy to such an extent, that by 1908 the country had the seventh largest economy in the world. This in turn led to further immigration and higher standards of living. It is also worth noting that the Tierra del Fuego gold rush that started around 1883 and lasted to around 1906 also contributed greatly to immigration. Unfortunately, Argentina was unable to retain it's acquired economic might; it failed to develop industrially at the same speed as the rest of the world, and the Great Depression of 1929 set in motion an economic decline that contributed to much civil and political unrest.

The impact of Perón, and modern Argentina
The election of Juan Perón in 1946 proved to be a defining point in Argentina's history; Perón was a demagogue who imprisoned (and reportedly tortured) his rivals and critics, and whose isolationist policies and radical spending contributed to severe inflation. With the death of Perón's extremely popular wife, Eva Duarte, in 1952, his popularity declined and he was eventually exiled following a coup in 1955. Despite this exile, Perón returned in 1973 and re-assumed the presidency, until his death in 1974, where he was the succeeded by his third wife. Peron's political philosophy, known as "Peronism", is a mixture of right wing nationalist and left wing populist theories; although Peronism has developed greatly over time, its core belief system is the foundation of Argentina's largest party, the Justicialist Party (although they have become increasingly left wing since the Kirchner administrations).

With the expulsion of Perón in 1955, Argentina's trend of military coups and failed governments continued, and the country faced further economic instability. Despite all of this, medical advancements and improvements to quality of life across the globe helped Argentina's mortality rate to decline, and the population grew at a faster rate than ever before. In April 1982, Argentine forces invaded the British territory of the Falkland Islands, leading to a ten week war between the nations, that ended with Argentina's surrender in June. The war had a relatively small death toll, but contributed to riots in Buenos Aires, which helped to topple the military dictatorship and established the current democratic system. Following a severe recession that began in 2001, President Néstor Kirchner assumed office in 2003, and his wife took over from 2007 to 2015; during the Kirchner administrations, more than eleven million people were lifted out of poverty, and Argentina's economy grew in stature to become one of the Group of Twenty.

In 1800, the population of the area of modern-day Lithuania was estimated to be just under 780,000. Lithuania’s rate of population growth would remain largely unchanged in the 19th century, as the Russian Empire would slowly but gradually develop its border regions. While large numbers of Lithuanians would emigrate west-ward (largely to the United States) between 1867 and 1868 after a famine in the country, growth would remain largely uninterrupted until the beginning of the First World War in 1912, which would see Lithuania, like much of the Baltic region, devastated as the battleground between the German and Russian Empires. As the conflict spread, those who were not made to evacuate by orders from the Russian government would face economic turmoil under German occupation, and as a result, Lithuania’s population would fall from just under 2.9 million in 1910, to under 2.3 million by 1920.

While Lithuania’s population would start to grow once more following the end of the First World War, this growth would be short-lived, as economic turmoil from the Great Depression, and later occupation and campaigns of mass extermination in the Second World War, most notably the extermination of 95 to 97 percent of the country’s Jewish population in the Holocaust, would cause Lithuania’s population growth to stagnate throughout the 1930s and 1940s. In the years following the end of the Second World War, Lithuania’s population would steadily climb, as industrialization by the Soviet Union would lead to improved economic growth and access to health, and campaigns of mass immunization and vaccination would lead to a sharp decline in child mortality. As a result, by the 1990s, Lithuania would have a population of over 3.7 million. However, Lithuania’s population would rapidly decline in the years following the dissolution of the Soviet Union in 1991, as economic crises and mass emigration from the country, paired with sharp declines in fertility, would result in a dramatic reduction in population. As a result, in 2020, Lithuania is estimated to have a population of just over 2.7 million.

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.

Selected reproductive and obstetric characteristics of women who gave birth at public health facilities in East Gojjam zone, Northwest Ethiopia, 2018.

Adverse maternal outcomes among women who gave birth at public health facilities in East Gojjam zone, Northwest Ethiopia, 2018.