Health of neonates born in the maternity hospital in Bern, Switzerland, 1880-1900 and 1914-1922.

The identification of factors impeding normal fetal development and growth is crucial for improving neonatal health. Historical studies are relevant because they show which parameters have influenced neonatal health in the past in order to better understand the present. We studied temporal changes of neonatal health outcomes (birth weight, gestational age, stillbirth rate) and the influence of different cofactors in two time periods. Moreover, we investigated particularly neonatal health in the wake of the 1918/19 influenza pandemic. Data were transcribed from the Bern Maternity Hospital and consists of two time periods: A) The years 1880, 1885, 1890, 1895 and 1900 (N = 1530, births' coverage 20%); B) The years 1914-1922 (N = 6924, births' coverage 40-50%). Linear regression models were used to estimate the effect of birth year on birth weight, and logistic regression models to estimate the effect of birth year and of the exposure to the pandemic on premature birth, stillborn and low birth weight (LBW). Mean birth weight increased only minimally between the two datasets; whereas, in the years 1914-1922, the preterm birth and stillbirth rates were markedly reduced compared with the years 1880-1900. Sex, parity, gestational age and maternal age were significantly associated with birth weight in both time periods. The probability of LBW was significantly increased in 1918 (OR 1.49 (95% CI 1.00-2.23)) and in 1919 (OR 1.55 (95% CI 1.02-2.36)) compared to 1914. Mothers who were heavily exposed to the influenza pandemic during pregnancy had a higher risk of stillbirth (OR 2.27 (95% CI 1.32-3.9)). This study demonstrated that factors influencing neonatal health are multifactorial but similar in both time periods. Moreover, the exposure to the 1918/19 pandemic was less associated with LBW and more associated with an increased risk of stillbirth. If this trend is confirmed by further studies, it could indicate some consistency across pandemics, as similar patterns have recently been shown for COVID-19.

From pandemic to endemic: Spatial-temporal patterns of influenza-like illness incidence in a Swiss canton, 1918-1924.

In pandemics, past and present, there is no textbook definition of when a pandemic is over, and how and when exactly a respiratory virus transitions from pandemic to endemic spread. In this paper we have compared the 1918/19 influenza pandemic and the subsequent spread of seasonal flu until 1924. We analysed 14,125 reports of newly stated 32,198 influenza-like illnesses from the Swiss canton of Bern. We analysed the temporal and spatial spread at the level of 497 municipalities, 9 regions, and the entire canton. We calculated incidence rates per 1000 inhabitants of newly registered cases per calendar week. Further, we illustrated the incidences of each municipality for each wave (first wave in summer 1918, second wave in fall/winter 1918/19, the strong later wave in early 1920, as well as the two seasonal waves in 1922 and 1924) on a choropleth map. We performed a spatial hotspot analysis to identify spatial clusters in each wave, using the Gi* statistic. Furthermore, we applied a robust negative binomial regression to estimate the association between selected explanatory variables and incidence on the ecological level. We show that the pandemic transitioned to endemic spread in several waves (including another strong wave in February 1920) with lower incidence and rather local spread until 1924 at least. At the municipality and regional levels, there were different patterns of spread both between pandemic and seasonal waves. In the first pandemic wave in summer 1918 the probability of higher incidence was increased in municipalities with a higher proportion of factories (OR 2.60, 95%CI 1.42-4.96), as well as in municipalities that had access to a railway station (OR 1.50, 95%CI 1.16-1.96). In contrast, the strong fall/winter wave 1918 was very widespread throughout the canton. In general, municipalities at higher altitude showed lower incidence. Our study adds to the sparse literature on incidence in the 1918/19 pandemic and subsequent years. Before Covid-19, the last pandemic that occurred in several waves and then became endemic was the 1918-19 pandemic. Such scenarios from the past can inform pandemic planning and preparedness in future outbreaks.

Intergenerational transmission of height in a historical population: From taller mothers to larger offspring at birth (and as adults).

Changes in growth and height reflect changes in nutritional status and health. The systematic surveillance of growth can suggest areas for interventions. Moreover, phenotypic variation has a strong intergenerational component. There is a lack of historical family data that can be used to track the transmission of height over subsequent generations. Maternal height is a proxy for conditions experienced by one generation that relates to the health/growth of future generations. Cross-sectional/cohort studies have shown that shorter maternal height is closely associated with lower birth weight of offspring. We analyzed the maternal height and offspring weight at birth in the maternity hospital in Basel, Switzerland, from 1896 to 1939 (N = ∼12,000) using generalized additive models (GAMs). We observed that average height of the mothers increased by ∼4 cm across 60 birth years and that average birth weight of their children shows a similarly shaped and upward trend 28 years later. Our final model (adjusted for year, parity, sex of the child, gestational age, and maternal birth year) revealed a significant and almost linear association between maternal height and birth weight. Maternal height was the second most important variable modeling birth weight, after gestational age. In addition, we found a significant association between maternal height and aggregated average height of males from the same birth years at time of conscription, 19 years later. Our results have implications for public health: When (female/maternal) height increases due to improved nutritional status, size at birth-and subsequently also the height in adulthood of the next generation-increases as well. However, the directions of development in this regard may currently differ depending on the world region.

Reinfections and Cross-Protection in the 1918/19 Influenza Pandemic: Revisiting a Survey Among Male and Female Factory Workers.

Objectives: The COVID-19 pandemic highlights questions regarding reinfections and immunity resulting from vaccination and/or previous illness. Studies addressing related questions for historical pandemics are limited. Methods: We revisit an unnoticed archival source on the 1918/19 influenza pandemic. We analysed individual responses to a medical survey completed by an entire factory workforce in Western Switzerland in 1919. Results: Among the total of n = 820 factory workers, 50.2% reported influenza-related illness during the pandemic, the majority of whom reported severe illness. Among male workers 47.4% reported an illness vs. 58.5% of female workers, although this might be explained by varied age distribution for each sex (median age was 31 years old for men, vs. 22 years old for females). Among those who reported illness, 15.3% reported reinfections. Reinfection rates increased across the three pandemic waves. The majority of subsequent infections were reported to be as severe as the first infection, if not more. Illness during the first wave, in the summer of 1918, was associated with a 35.9% (95%CI, 15.7-51.1) protective effect against reinfections during later waves. Conclusion: Our study draws attention to a forgotten constant between multi-wave pandemics triggered by respiratory viruses: Reinfection and cross-protection have been and continue to be a key topic for health authorities and physicians in pandemics, becoming increasingly important as the number of waves increases.

Short-termed changes in quantitative ultrasound estimated bone density among young men in an 18-weeks follow-up during their basic training for the Swiss Armed Forces.

Background: Quantitative Ultrasound (QUS) methods have been widely used to assess estimated bone density. This study aimed to assess changes in estimated bone density in association with changes in body composition, physical activity, and anthropometry. Methods: We examined changes in anthropometry, body composition, and physical activity associated with changes in estimated bone mineral density (measured using quantitative ultrasound with a heel ultrasound device indicating broadband ultrasound attenuation BUA and speed of sound SOS) in a follow-up sample of n = 73 young men at the beginning and again 18 weeks later at the end of basic military training. Results: At the end of the basic training, the subjects were on average significantly heavier (+1.0%), slightly taller (+0.5%) and had a higher fat mass (+6.6%) and grip strength (+8.6%). A significant decrease in mean physical activity (-49.5%) and mean estimated bone density calculated with BUA (-7.5%) was observed in the paired t-test. The results of the multivariable linear regressions (backward selection) show that changes in skeletal muscle mass (delta = 2nd measurement minus 1st measurement) have negative and body weight (delta) have positive association with the speed of sound SOS (delta), while fat mass (delta) and physical activity (delta) had the strongest negative associations with estimated bone mineral density (delta). In particular, we found a negative association between fat mass (delta) and estimated bone mineral density (delta, estimated with BUA). Conclusion: Our study suggests that estimated bone density from the calcaneus can change within a few months even in young and mostly healthy individuals, depending upon physical activity levels and other co-factors. Further studies including other troop types as control groups as well as on women should follow in order to investigate this public health relevant topic in more depth. To what extent the estimated bone density measurement with quantitative ultrasound is clinically relevant needs to be investigated in further studies.

Body height among adult male and female Swiss Health Survey participants in 2017: Trends by birth years and associations with self-reported health status and life satisfaction.

The increase in adult height for 150 years is linked to overall improvements in nutrition, hygiene, and living standards. Height is positively associated with general health and success on various levels (e.g. quality of life, earnings or happiness). The aim of this study was to investigate whether different subgroups show different trends across birth cohorts. We wanted to know whether taller individuals considered themselves as healthier and their quality of life as better than shorter individuals. We included 19,435 participants from the Swiss population-based Health Survey 2017. GAM were used to assess nonlinear associations between height and birth year. Multinomial logistic regression was used to predict probabilities of self-rated health in relation to height. The increase in average height slows down from the 1970s birth cohorts. Participants with parents from Central/Northern/Western Europe (men 177.9 cm, women: 165.1 cm) or Eastern Europe (men 178.7 cm, women: 165.7 cm) were taller than participants with parents from South America (men 174.3 cm, women: 161. cm) and Asia (men 173.2 cm, women: 160.1 cm). Participants with tertiary education were taller than participants from education levels (mean difference men: 4.5 cm, women: 5.0 cm). Height was positively associated with self-declared aspects of health and life satisfaction. These results support the conclusion that body height as a co-factor of health aspects should be considered in public health research. Although adult body height can no longer be influenced, nutritional status and thus also healthy growth can be influenced in childhood by public health programs, by eliminating social inequalities, and by strengthen healthy living conditions.

Life-history tradeoffs in a historical population (1896-1939) undergoing rapid fertility decline: Costs of reproduction?

Evolutionary demographers often invoke tradeoffs between reproduction and survival to explain reductions in fertility during demographic transitions. The evidence for such tradeoffs in humans has been mixed, partly because tradeoffs may be masked by individual differences in quality or access to resources. Unmasking tradeoffs despite such phenotypic correlations requires sophisticated statistical analyses that account for endogeneity among variables and individual differences in access to resources. Here we tested for costs of reproduction using N=13,663 birth records from the maternity hospital in Basel, Switzerland, 1896-1939, a period characterized by rapid fertility declines. We predicted that higher parity is associated with worse maternal and offspring condition at the time of birth, adjusting for age and a variety of covariates. We used Bayesian multivariate, multilevel models to simultaneously analyze multiple related outcomes while accounting for endogeneity, appropriately modeling non-linear effects, dealing with hierarchical data structures, and effectively imputing missing data. Despite all these efforts, we found virtually no evidence for costs of reproduction. Instead, women with better access to resources had fewer children. Barring limitations of the data, these results are consistent with demographic transitions reflecting women's investment in their own embodied capital and/or the adoption of maladaptive low-fertility norms by elites.

Historically High Excess Mortality During the COVID-19 Pandemic in Switzerland, Sweden, and Spain.

BACKGROUND: Excess mortality quantifies the overall mortality impact of a pandemic. Mortality data have been accessible for many countries in recent decades, but few continuous data have been available for longer periods. OBJECTIVE: To assess the historical dimension of the COVID-19 pandemic in 2020 for 3 countries with reliable death count data over an uninterrupted span of more than 100 years. DESIGN: Observational study. SETTING: Switzerland, Sweden, and Spain, which were militarily neutral and not involved in combat during either world war and have not been affected by significant changes in their territory since the end of the 19th century. PARTICIPANTS: Complete populations of these 3 countries. MEASUREMENTS: Continuous series of recorded deaths (from all causes) by month from the earliest available year (1877 for Switzerland, 1851 for Sweden, and 1908 for Spain) were jointly modeled with annual age group-specific death and total population counts using negative binomial and multinomial models, which accounted for temporal trends and seasonal variability of prepandemic years. The aim was to estimate the expected number of deaths in a pandemic year for a nonpandemic scenario and the difference in observed and expected deaths aggregated over the year. RESULTS: In 2020, the number of excess deaths recorded per 100 000 persons was 100 (95% credible interval [CrI], 60 to 135) for Switzerland, 75 (CrI, 40 to 105) for Sweden, and 155 (CrI, 110 to 195) for Spain. In 1918, excess mortality was 6 to 7 times higher. In all 3 countries, the peaks of monthly excess mortality in 2020 were greater than most monthly excess mortality since 1918, including many peaks due to seasonal influenza and heat waves during that period. LIMITATION: Historical vital statistics might be affected by minor completeness issues before the beginning of the 20th century. CONCLUSION: In 2020, the COVID-19 pandemic led to the second-largest infection-related mortality disaster in Switzerland, Sweden, and Spain since the beginning of the 20th century. PRIMARY FUNDING SOURCE: Foundation for Research in Science and the Humanities at the University of Zurich, Swiss National Science Foundation, and National Institute of Allergy and Infectious Diseases.

Public Health Interventions, Epidemic Growth, and Regional Variation of the 1918 Influenza Pandemic Outbreak in a Swiss Canton and Its Greater Regions.

Public health interventions implemented during the coronavirus disease 2019 (COVID-19) pandemic are based on experience gained from past pandemics. The 1918 influenza pandemic is the most extensively researched historical influenza outbreak. All 9335 reports available in the State Archives on 121 152 cases of influenza-like illness from the canton of Bern from 473 of 497 municipalities (95.2%) were collected; the cases were registered between 30 June 1918 and 30 June 1919. The overall incidence rates of newly registered cases per week for the 9 greater regions of Bern for both the first and second waves of the pandemic were calculated. Relative incidence rate ratios (RIRRs) were calculated to estimate the change in the slope of incidence curves associated with public health interventions. During the first wave, school closures (RIRR, 0.16 [95% CI, 0.15 to 0.17]) and restrictions of mass gatherings (RIRR, 0.57 [CI, 0.54 to 0.61]) were associated with a deceleration of epidemic growth. During the second wave, in autumn 1918, cantonal authorities initially reacted hesitantly and delegated the responsibility to enact interventions to municipal authorities, which was associated with a lack of containment of the second wave. A premature relaxation of restrictions on mass gatherings was associated with a resurgence of the epidemic (RIRR, 1.18 [CI, 1.12 to 1.25]). Strikingly similar patterns were found in the management of the COVID-19 outbreak in Switzerland, with a considerably higher amplitude and prolonged duration of the second wave and much higher associated rates of hospitalization and mortality.

Impact of World War 1 on placenta weight, birth weight and other anthropometric parameters of neonatal health.

BACKGROUND: Wars do not only affect combatant countries, populations in neutral zones can be afflicted by circumjacent conflicts as well, posing a great health burden on mothers and newborns. As neonatal health remains an ongoing cause for concern, identifying determinants that impede fetal growth is crucial. Under this pretext, the study aimed to analyze the impact of World War 1 in the neutral city of Basel on neonatal health by assessing changes in anthropometric parameters. METHODS: A retrospective analysis of yearly cross sections of term births in the maternity hospital of Basel from 1912 to 1923 was conducted (n = 3718). We tested adjusted anthropometry for time trends in comparison to a pre-war baseline, including birth weight, placenta weight, birth length, ponderal index and gestational age. Interrelations of placenta weights and birth weights were examined separately through birth weight to placenta weight (BW/PW) ratios and residuals of placenta weight to birth weight regressions. RESULTS: Birth weights, placenta weights and residuals were at their lowest in 1918/19, a trend not reflected in BW/PW ratios. Birth lengths remained low while ponderal indexes declined during the entire period of war, gestational age remained rather stable. DISCUSSION: 1918/19 were the pinnacle years for the population of Basel, who were suffering from general detrimental economic conditions, a food supply crisis and an outbreak of the Spanish Flu. These adverse circumstances coincided with low birth and placenta weights, residuals depicting the correlation of birth weights to placental weights more closely than bw/pw ratios.

Filling the weight gap: Estimating body weight and BMI using height, chest and upper arm circumference of Swiss conscripts in the first half of the 20th century.

We estimate weight and BMI values based on height, chest circumference, and mid upper arm circumference measures of Swiss conscripts in the city of Zurich for each year between 1904 and 1932. Height, chest circumference, and mid upper arm circumference were measured each year from 1904 to 1951. Body weight is available from 1933 to 1951. We used prediction equations from the literature, and also developed our own equations, which we tested and validated on the dataset from 1933 to 1951. We used a representative sample of usually 19-year-old Swiss males (N = 88,792, coverage > 88 %). There was an increase in average height and chest circumference between 1904 and 1951. During both world wars, chest circumference, mid upper arm circumference, weight, and BMI decreased, while height stagnated. Overall mean weight and BMI increased from 1904 to 1951, but decreased during the Great Depression. After World War II, weight quickly returned to the pre-war and pre-Great Depression level, while BMI had not reached the 1933 level by 1951. Average weights of the lower and middle socioeconomic groups were catching up with average weight of the upper socioeconomic group from 1904 to 1951. The convergence in height is less pronounced. Finally, we show that it is possible to accurately predict mean weight and BMI from other anthropometric measurements. We suggest that our estimation approach could be replicated for other historical populations to obtain more information on how nutritional status changed over time.

Have Swiss adult males and females stopped growing taller? Evidence from the population-based nutrition survey menuCH, 2014/2015.

Data from the National Nutrition Survey for adults (menuCH) allow for the assessment of recent trends in measured height by year of birth for adult men and women from a population-based sample. The aim of the present study was to test if - similarly to conscripts and schoolchildren - the Swiss adult population stopped growing taller in recent birth cohorts, and if so, when the change occurred. We found that - when self-reported - height was overestimated on average by about 1 cm in both men and women, with an increasing tendency with older age and with shorter height. Average measured height increased by 4.5-5.0 cm for adult men and women between the birth years 1937-1949 and 1990-1995. However, this increase was not linear, and starting with the 1970s birth years, average height plateaued on a level of about 178 cm for men and 166 cm for women. Being born outside of Switzerland or adjustment for potential shrinkage with increasing age did not change this temporal pattern. We also found shorter average height among participants from the Italian part of Switzerland and those with lower educational level. It remains unclear if the phenomenon of stabilisation affects all subgroups of the Swiss population. Future studies should combine a larger number of population-based surveys to enhance the sample size, for example, for people with a migration background or with different educational levels. Continuing growth monitoring needs to be performed to assess if environmental and demographic changes with an impact on body growth (adverse trends in nutrition, increasing social inequality in health, ethnic composition of the population) positively or negatively influence future trends in average height.

Spatial Association of Food Sales in Supermarkets with the Mean BMI of Young Men: An Ecological Study.

Supermarket food sales data might serve as a simple indicator of population-level dietary habits that influence the prevalence of excess weight in local environments. To test this possibility, we investigated how variation in store-level food sales composition across Switzerland is associated with the mean Body Mass Index (BMI) of young men (Swiss Army conscripts) living near the stores. We obtained data on annual food sales (2011) for 553 stores from the largest supermarket chain in Switzerland, identified foods commonly regarded as "healthy" or "unhealthy" based on nutrient content, and determined their contribution to each store's total sales (Swiss francs). We found that the sales percentages of both "healthy" and "unhealthy" food types varied by 2- to 3-fold among stores. Their balance ranged from -15.3% to 18.0% of total sales; it was positively associated with area-based socioeconomic position (r = 0.63) and negatively associated with the mean BMI of young men in the area (r = -0.42). Thus, even though we compared supermarkets from a single chain, different shopping behaviors of customers caused stores in privileged areas to sell relatively more healthy food. Knowledge about such patterns could help in designing in-store interventions for healthier nutrition and monitoring their effects over time.

Associations between anthropometric indices, blood pressure and physical fitness performance in young Swiss men: a cross-sectional study.

OBJECTIVES: To assess the benefit of waist circumference (WC) measurements during routine conscription medical examination in two military conscription centres in Switzerland. We compared the prevalence of overweight and obesity assessed by body mass index (BMI) with the prevalence of elevated disease risks assessed by WC and waist-to-height ratio (WHtR). We investigated how these measures were associated with systolic blood pressure, physical fitness performance and socioeconomic determinants. DESIGN: Cross-sectional survey. SETTING: Two Swiss conscription centres in 2016. PARTICIPANTS: 1548 Swiss male conscripts, 18-22 years old. MAIN OUTCOME: Prevalences of elevated WC, WHtR and BMI values according to WHO categories. Secondary outcomes include systolic blood pressure, physical fitness performance and endurance performance. RESULTS: Using BMI cut-points, 25.0% of all conscripts were overweight or obese. When applying WC cut-points, 9.2% had an increased disease risk, while 14.8% of the conscripts were at risk using WHtR cut-points. In the BMI range of 25.0-27.4 kg/m2, 3.6% showed an increased disease risk when using WC and 24.6% when using WHtR cut-points. Of the conscripts with a BMI of 27.5-29.9 kg/m2, 72.4% had an increased disease risk using WHtR, and 42.5% when using WC cut-points. Determinants of elevated BMI, WC and WHtR were low occupational status, rural residential area, older age and location in central and Northwest Switzerland. Systolic blood pressure increased with increasing BMI, WC and WHtR. Physical fitness and endurance test performances decreased with increasing BMI, WC and WHtR. CONCLUSION: In addition to BMI, WC and WHtR add relevant information to the health assessment of young men. However, the prevalence of overweight/increased health risk differed when using BMI, WC or WHtR. Further studies should include measures of body composition to test whether these differences arise from muscular young men within the overweight BMI range, who had a normal WC.

Ladies first: Female and male adult height in Switzerland, 1770-1930.

When investigating the well-being of a society, the living conditions of females are of special importance, not only due to the immediate impact for those directly involved, but also because of the potential intergenerational effects. Studying the dimorphism in the mean height helps to depict variation in the basic biological sex difference due to gender-related factors that potentially determine net nutrition. To expand knowledge of diachronic development in Swiss well-being conditions we investigate changes in the height of adult females born 1770-1930, and compare the series with data on contemporary males from the same sources: We employ a sample of N = 21'028 women and N = 21'329 men from passport-, convict-, maternity hospital-, and voluntary World War II army auxiliary records. The secular height trend is found both in males, from the 1870s/1880s, and in females starting with the 1840s/1850s birth cohorts. During the decades under study, mean height increased from 157 cm to 164 cm in female and 167 cm to 172 cm in male passport applicants, 154 cm to 159 cm in female and 167 cm to 169 cm in male convicts, 159 cm to 163 cm in female auxiliaries, and 155 cm to 159 cm in females giving birth in the maternity hospital of Basel. Because females seem to have started the secular trend in height earlier than their male contemporaries, the height dimorphism decreased during the second half of the 19th century. Differences between socio-economic status (SES) and data sources are found in both females and males: Women with low SES were significantly shorter than those of the other SES groups in all sources (on average 1.40 cm, p-values between 0.00 and 0.03). In men we found individuals of upper SES to be significantly taller (on average 1.96 cm, p-value = 0.00-0.10). Concerning differences between the sources, overall, passport applicants were the tallest for men as well as women; in females the individuals measured at the maternity hospital and in prison were the shortest. The variances across the datasets highlight the importance of considering different sources to depict average living conditions. Noteworthy is the finding that the diverse sources under study all show the same trajectory of increasing mean height over the course of the 19th century. In the long run, the improving net nutritional status of Swiss females may have been one of the contributors behind the general rise in well-being of the country's population from the later 19th century onwards.

Temporal trends, regional variation and socio-economic differences in height, BMI and body proportions among German conscripts, 1956-2010.

OBJECTIVE: We analyse temporal trends and regional variation among the most recent available anthropometric data from German conscription in the years 2008-2010 and their historical contextualization since 1956. Design/setting/subjects The overall sample included German conscripts (N 13 857 313) from 1956 to 2010. RESULTS: German conscripts changed from growing in height to growing in breadth. Over the analysed 54 years, average height of 19-year-old conscripts increased by 6·5 cm from 173·5 cm in 1956 (birth year 1937) to 180·0 cm in 2010 (birth year 1991). This increase plateaued since the 1990s (1970s birth years). The increase in average weight, however, did not lessen during the last two decades but increased in two steps: at the end of the 1980s and after 1999. The weight and BMI distributions became increasingly right-skewed, the prevalence of overweight and obesity increased from 11·6 % and 2·1 % in 1984 to 19·9 % and 8·5 % in 2010, respectively. The north-south gradient in height (north = taller) persisted during our observations. Height and weight of conscripts from East Germany matched the German average between the early 1990s and 2009. Between the 1980s and the early 1990s, the average chest circumference increased, the average difference between chest circumference when inhaling and exhaling decreased, as did leg length relative to trunk length. CONCLUSIONS: Measuring anthropometric data for military conscripts yielded year-by-year monitoring of the health status of young men at a proscribed age. Such findings contribute to a more precise identification of groups at risk and thus help with further studies and to target interventions.

From Undernutrition to Overnutrition: The Evolution of Overweight and Obesity among Young Men in Switzerland since the 19th Century.

OBJECTIVE: The global obesity epidemic continues, new approaches are needed to understand the causes. We analyzed data from an evolutionary perspective, stressing developmental plasticity. METHODS: We present diachronical height, weight, and BMI data for 702,902 Swiss male conscripts aged 18-20 years, a representative, standardized and unchanged data source. RESULTS: From 1875 to 1879, the height distribution was slightly left-skewed; 12.1% of the conscripts were underweight, overweight and obesity were rare. The BMI-to-height relationship was positive but not linear, and very short conscripts were particularly slim. Since the 1870s, Swiss conscripts became taller, a trend that markedly slowed in the 1990s. In contrast, weight increased in two distinct steps at the end of the 1980s and again after 2002. Since 2010, BMI did not increase but stabilized at a high level. CONCLUSIONS: The body of young men adapted differently to varying living conditions over time: First, less investment in height and weight under conditions of undernutrition and food uncertainty; second, more investment in height under more stable nutritional conditions; third, development of obesity during conditions of plateaued height growth, overnutrition, and decreasing physical activity. This example contributes to the evaluation of hypotheses on human developmental plasticity.

From left-skewness to symmetry: how body-height distribution among Swiss conscripts has changed shape since the late 19th century.

BACKGROUND: It is generally accepted that height distribution in modern populations is nearly symmetrical. However, it may deviate from symmetry when nutritional status is inadequate. Aim and subjects: This study provides an analysis of changes in the shape of the height distributions among Swiss conscripts (n = 267,829) over the past 130 years based on a highly representative, standardized and unchanged data source. RESULTS: The analysed distributions from the 1870s-1890s conscription years are markedly left-skewed (-0.76 to -0.82), with short and very short men significantly over-represented. Standard deviation is 7.7 cm. In particular, the left tails of the late-19th- and early-20th-century distributions are very heavy. In the first half of the 20th century the first signs of a diminution of the heavy left tail are observable, by the 1970s the phenomenon disappears and height distribution becomes symmetrical; standard deviation is now 6.5 cm. CONCLUSION: The relatively strong left-skewness during the late 19th and early 20th centuries may have been due to the interaction of a number of causes, chiefly malnutrition, a wider range in physical development at age 19 and widespread iodine deficiency.