The Impact of Multiple Births on Fertility: Stopping and Spacing in the United States During the Demographic Transition.

Multiple births strain mothers' and families' resources in ways that should highlight preferences for family size, birth spacing, and parity-dependent stopping behavior. Couples with surviving twins reach their target family size sooner than other couples and should be more likely to practice family limitation. Twins are also a greater burden on the mother's time and health, which could lead to postponing the next birth, even among couples who want additional children. We examine these hypotheses by analyzing families with twins in the 1900 and 1910 U.S. Censuses. Using reconstructed birth histories for more than 7 million women in the IPUMS full-count 1900 and 1910 datasets and event-history methods (Kaplan-Meier curves, cure models), we find clear evidence of family limitation following a multiple birth. Couples who had twins or triplets were more likely to stop childbearing, and those who continued having children delayed their next birth. Responses to multiple births were larger in groups previously identified as leaders in the transition to smaller families, and roughly one third of couples stopped after one or two children. We find no evidence that some groups relied primarily on birth spacing to reduce family size while others relied primarily on stopping.

The Influence of Kin Proximity on the Reproductive Success of American Couples, 1900-1910.

Children require a large amount of time, effort, and resources to raise. Physical help, financial contributions, medical care, and other types of assistance from kin and social network members allow couples to space births closer together while maintaining or increasing child survival. We examine the impact of kin availability on couples' reproductive success in the early twentieth-century United States with a panel data set of over 3.1 million couples linked between the 1900 and 1910 U.S. censuses. Our results indicate that kin proximity outside the household was positively associated with fertility, child survival, and net reproduction, and suggest that declining kin availability was an important contributing factor to the fertility transition in the United States. We also find important differences between maternal and paternal kin inside the household-including higher fertility among women residing with their mother-in-law than among those residing with their mother-that support hypotheses related to the contrasting motivations and concerns of parents and parents-in-law.

Reconstruction of Birth Histories for the Study of Fertility in the United States, 1830-1910.

This paper describes a method to reconstruct complete birth histories for women in the 1900 and 1910 U. S. census IPUMS samples. The method is an extension of an earlier method developed by Luther and Cho (1988). The basic method relies on the number of children ever born, number of children surviving, number of children coresident in the household and age-specific fertility rates for the population to probabilistically assign an "age" to deceased and unmatched children. Modifications include the addition of an iterative Poisson regression model to fine-tune age-specific fertility inputs. The potential of complete birth histories for the study of the U.S. fertility transition is illustrated with a few examples.

Patients with laboratory evidence of West Nile virus disease without reported fever.

In 2013, the national surveillance case definition for West Nile virus (WNV) disease was revised to remove fever as a criterion for neuroinvasive disease and require at most subjective fever for non-neuroinvasive disease. The aims of this project were to determine how often afebrile WNV disease occurs and assess differences among patients with and without fever. We included cases with laboratory evidence of WNV disease reported from four states in 2014. We compared demographics, clinical symptoms and laboratory evidence for patients with and without fever and stratified the analysis by neuroinvasive and non-neuroinvasive presentations. Among 956 included patients, 39 (4%) had no fever; this proportion was similar among patients with and without neuroinvasive disease symptoms. For neuroinvasive and non-neuroinvasive patients, there were no differences in age, sex, or laboratory evidence between febrile and afebrile patients, but hospitalisations were more common among patients with fever (P < 0.01). The only significant difference in symptoms was for ataxia, which was more common in neuroinvasive patients without fever (P = 0.04). Only 5% of non-neuroinvasive patients did not meet the WNV case definition due to lack of fever. The evidence presented here supports the changes made to the national case definition in 2013.

The impact of kin availability, parental religiosity, and nativity on fertility differentials in the late 19th-century United States.

METHODS: Most quantitative research on fertility decline in the United States ignores the potential impact of cultural and familial factors. We rely on new complete-count data from the 1880 U.S. census to construct couple-level measures of nativity/ethnicity, religiosity, and kin availability. We include these measures with a comprehensive set of demographic, economic, and contextual variables in Poisson regression models of net marital fertility to assess their relative importance. We construct models with and without area fixed effects to control for unobserved heterogeneity. CONTRIBUTION: All else being equal, we find a strong impact of nativity on recent net marital fertility. Fertility differentials among second generation couples relative to the native-born white population of native parentage were in most cases less than half of the differential observed among first generation immigrants, suggesting greater assimilation to native-born American childbearing norms. Our measures of parental religiosity and familial propinquity indicated a more modest impact on marital fertility. Couples who chose biblical names for their children had approximately 3% more children than couples relying on secular names while the presence of a potential mother-in-law in a nearby households was associated with 2% more children. Overall, our results demonstrate the need for more inclusive models of fertility behavior that include cultural and familial covariates.

Ready, Willing, and Able? Impediments to the Onset of Marital Fertility Decline in the United States.

This study relies on IPUMS samples of the 1850, 1860, 1870, and 1880 censuses, aggregate census data, and the timing of state laws criminalizing abortion to construct regional estimates of marital fertility in the United States and estimate correlates of marital fertility. The results show a significant lag between the onset of marital fertility decline in the nation's northeastern census divisions and its onset in western and southern census divisions. Empirical models indicate the presence of cultural, economic, and legal impediments to the diffusion of marital fertility control and illustrate the need for more inclusive models of fertility decline.

The impact of socio-economic status on net fertility during the historical fertility decline: a comparative analysis of Canada, Iceland, Sweden, Norway, and the USA.

We used micro-level data from the censuses of 1900 to investigate the impact of socio-economic status on net fertility during the fertility transition in five Northern American and European countries (Canada, Iceland, Norway, Sweden, and the USA). The study is therefore unlike most previous research on the historical fertility transition, which used aggregate data to examine economic correlates of demographic behaviour at regional or national levels. Our data included information on number of children by age, occupation of the mother and father, place of residence, and household context. The results show highly similar patterns across countries, with the elite and upper middle classes having considerably lower net fertility early in the transition. These patterns remain after controlling for a range of individual and community-level fertility determinants and geographical unobserved heterogeneity.

Wealth and Child Mortality in the Nineteenth-Century United States: Evidence from Three Panels of American Couples, 1850-1880.

With only a few exceptions, the historical study of individual-level correlates of child mortality in the United States has been limited to the period surrounding the turn of the twentieth century, when children ever born and children surviving data collected by the 1900 and 1910 censuses allow indirect estimation of child mortality. The recent release of linked census data, such as the IPUMS MLP datasets, allows a different type of indirect estimation over a longer period. By following couples across subsequent decennial censuses, it is possible to infer child mortality by measuring whether couples' own children in the first census were still present in the second census. We focus our analysis on children aged 1-3 in the first of two linked censuses, who were less likely to be undercounted by the census than infants, and unlikely to be living apart from their parents in the second census. We estimate child mortality over the intervening decade and use OLS regression to correlate that mortality to the residence location and socioeconomic characteristics of their parents' households. We limit our analysis to three panel datasets for married couples linked between the 1850-60, 1860-70, and 1870-80 censuses, when real estate and personal estate wealth data were collected. Our results indicate a significant negative relationship between wealth and child mortality across all regions of the United States and over the entire period examined.

Early Fertility Decline in the United States: Tests of Alternative Hypotheses using New IPUMS Complete-Count Census Microdata and Enhanced County-Level Data.

The U. S. fertility transition in the nineteenth century is unusual. Not only did it start from a very high fertility level and very early in the nation's development, but it also took place long before the nation's mortality transition, industrialization, and urbanization. This paper assembles new county-level, household-level, and individual-level data, including new complete-count IPUMS microdata databases of the 1830-1880 censuses, to evaluate different theories for the nineteenth-century American fertility transition. We construct cross-sectional models of net fertility for currently-married white couples in census years 1830-1880 and test the results with a subset of couples linked between the 1850-1860, 1860-1870, and 1870-1880 censuses. We find evidence of marital fertility control consistent with hypotheses as early as 1830. The results indicate support for several different but complementary theories of the early U.S. fertility decline, including the land availability, conventional structuralist, ideational, child demand/quality-quantity tradeoff, and life-cycle savings theories.

Genome dynamics and its impact on evolution of Escherichia coli.

The Escherichia coli genome consists of a conserved part, the so-called core genome, which encodes essential cellular functions and of a flexible, strain-specific part. Genes that belong to the flexible genome code for factors involved in bacterial fitness and adaptation to different environments. Adaptation includes increase in fitness and colonization capacity. Pathogenic as well as non-pathogenic bacteria carry mobile and accessory genetic elements such as plasmids, bacteriophages, genomic islands and others, which code for functions required for proper adaptation. Escherichia coli is a very good example to study the interdependency of genome architecture and lifestyle of bacteria. Thus, these species include pathogenic variants as well as commensal bacteria adapted to different host organisms. In Escherichia coli, various genetic elements encode for pathogenicity factors as well as factors, which increase the fitness of non-pathogenic bacteria. The processes of genome dynamics, such as gene transfer, genome reduction, rearrangements as well as point mutations contribute to the adaptation of the bacteria into particular environments. Using Escherichia coli model organisms, such as uropathogenic strain 536 or commensal strain Nissle 1917, we studied mechanisms of genome dynamics and discuss these processes in the light of the evolution of microbes.

Decennial Life Tables for the White Population of the United States, 1790-1900.

This article constructs new life tables for the white population of the United States in each decade between 1790 and 1900. Drawing from several recent studies, it suggests best estimates of life expectancy at age 20 for each decade. These estimates are fitted to new standards derived from the 1900-02 rural and 1900-02 overall DRA life tables using a two-parameter logit model with fixed slope. The resulting decennial life tables more accurately represent sex-and age-specific mortality rates while capturing known mortality trends.

From '20. and odd' to 10 million: The growth of the slave population in the United States.

This research note describes the growth of the slave population in the United States and develops several new measures of its size and growth, including an estimate of the total number of slaves who ever lived in the United States. Estimates of the number of births and slave imports are provided in ten-year increments between 1619 and 1860 and in one-year increments between 1861 and 1865. The results highlight the importance of natural increase to the rapid growth of the U.S. slave population and indicate that approximately 10 million slaves lived in the United States, where they contributed 410 billion hours of labor. A concluding discussion highlights a few descriptive statistics historians might find useful, including the cumulative number of slaves who lived in the United States by decade and the proportion of slaves who were living at various moments in U.S. history, including shortly after the ratification of the Constitution in 1788 and at the start of the American Civil War in 1861.

Immigration and Child Mortality: Lessons from the United States at the turn of the Twentieth Century.

The societal integration of immigrants is a great concern in many of today's Western societies, and has been so for a long time. Whether we look at Europe in 2015 or the United States at the turn of the twentieth century, large flows of immigrants pose challenges to receiving societies. While much research has focused on the socioeconomic integration of immigrants there has been less interest in their demographic integration, even though this can tell us as much about the way immigrants fare in their new home country. In this paper we study the disparities in infant and child mortality across nativity groups and generations, using new, high-density census data. In addition to describing differentials and trends in child mortality among 14 immigrant groups relative to the native-born white population of native parentage, we focus special attention on the association between child mortality, immigrant assimilation, and the community-level context of where immigrants lived. Our findings indicate substantial nativity differences in child mortality, but also that factors related to the societal integration of immigrants explains a substantial part of these differentials. Our results also point to the importance of spatial patterns and contextual variables in understanding nativity differentials in child mortality.

Carbohydrate receptors of bacterial adhesins: implications and reflections.

Bacteria entering a host depend on adhesins to achieve colonization. Adhesins are bacterial surface structures mediating binding to host surficial areas. Most adhesins are composed of one or several proteins. Usually a single bacterial strain is able to express various adhesins. The adhesion type expressed may influence host-, tissue or even cell tropism of Gram-negative and of Gram-positive bacteria. The binding of fimbrial as well as of afimbrial adhesins of Gram-negative bacteria to host carbohydrate structures (=receptors) has been elucidated in great detail. In contrast, in Gram-positives, most well studied adhesins bind to proteinaceous partners. Nevertheless, for both bacterial groups the binding of bacterial adhesins to eukaryotic carbohydrate receptors is essential for establishing colonization or infection. The characterization of this interaction down to the submolecular level provides the basis for strategies to interfere with this early step of infection which should lead to the prevention of subsequent disease. However, this goal will not be achieved easily because bacterial adherence is not a monocausal event but rather mediated by a variety of adhesins.

Specific single or double proline substitutions in the "spring-loaded" coiled-coil region of the influenza hemagglutinin impair or abolish membrane fusion activity.

We tested the role of the "spring-loaded" conformational change in the fusion mechanism of the influenza hemagglutinin (HA) by assessing the effects of 10 point mutants in the region of high coiled-coil propensity, HA2 54-81. The mutants included proline substitutions at HA2 55, 71, and 80, as well as a double proline substitution at residues 55 and 71. Mutants were expressed in COS or 293T cells and assayed for cell surface expression and structural features as well as for their ability to change conformation and induce fusion at low pH. We found the following: Specific mutations affected the precise carbohydrate structure and folding of the HA trimer. All of the mutants, however, formed trimers that could be expressed at the cell surface in a form that could be proteolytically cleaved from the precursor, HA0, to the fusion-permissive form, HA1-S-S-HA2. All mutants reacted with an antibody against the major antigenic site and bound red blood cells. Seven out of ten mutants displayed a wild-type (wt) or moderately elevated pH dependence for the conformational change. V55P displayed a substantial reduction (approximately 60- 80%) in the initial rate of lipid mixing. The other single mutants displayed efficient fusion with the same pH dependence as wt-HA. The double proline mutant V55P/ S71P displayed no fusion activity despite being well expressed at the cell surface as a proteolytically cleaved trimer that could bind red blood cells and change conformation at low pH. The impairment in fusion for both V55P and V55P/S71P was at the level of outer leaflet lipid mixing. We interpret our results in support of the hypothesis that the spring-loaded conformational change is required for fusion. An alternate model is discussed.

[Climate changes and emerging diseases. What new infectious diseases and health problem can be expected?]. / Die Auswirkungen des Klimawandels. Welche neuen Infektionskrankheiten und gesundheitlichen Probleme sind zu erwarten?

Increasing temperatures, but also other climatic factors, will have an impact on human health. Apart from the direct consequences of extreme weather conditions (e.g., heat-related fatalities), indirect health consequences in the long-term are also of great importance. In addition to a likely increase in allergic diseases and additional complications in the course of cardiovascular and respiratory diseases, infectious diseases are of particular interest. In Germany, endemic pathogens, such as hantavirus (with its reservoir in small rodents), tick-borne pathogens (Borrelia burgdorferi, tick-borne encephalitis virus), and certain food- and water-borne pathogens, are of concern. Mild winters favor rodent populations and may result in hantavirus epidemics in the subsequent summer period. Statistical analyses show a significant association between temperature and campylobacter incidence in Germany. An outbreak of rodent-borne leptospirosis among strawberry harvesters enhanced by heavy rainfalls illustrates how weather conditions may influence disease occurrence. Pathogens that are non-endemic in Germany but are imported by humans, vectors, and reservoir animals pose an additional risk to the population. Increasing temperatures improve the conditions for establishment of new vectors and for autochthonous transmission of some pathogens (e.g., chikungunya, dengue, West Nile virus, malaria, or leishmaniasis). Climatic and ecologic conditions in Germany currently do not favor autochthonous outbreaks for most of these pathogens. However, if temperatures increase, as expected, such outbreaks will become more likely. Germany should enhance its research in public health activities in the field of climate change and infectious diseases.

Fertility decline in the United States, 1850-1930: New Evidence from Complete-Count Datasets.

Between 1835 and 1935, total fertility in the United States fell from 7.0 to 2.1. New IPUMS complete-count microdata databases of the 1850, 1880, 1910, and 1930 U. S. censuses allow us to study the fertility decline in more detail than previously possible. We construct comprehensive models of couples' fertility incorporating a wide variety of economic, social, cultural and familial factors, including measures of parental religiosity and kin availability outside of the household. The results indicate that while shifts in the occupational structure and increasing urbanization of the population provide the most consistent and substantive contribution to fertility decline over the period, cultural and religious attitudes - as proxied by parents' nativities and child naming practices - played a major role in couples' childbearing decisions.

Becoming American: Intermarriage during the Great Migration to the United States.

Although intermarriage is a common indicator of immigrant integration into host societies, most research has focused on how individual characteristics determine intermarriage. This study uses the 1910 IPUMS census sample to analyze how contextual factors affected intermarriage among European immigrants in the United States. Newly available, complete-count census microdata permits the construction of contextual measures at a much lower level of aggregation-the county-in this analysis than in previous studies. Our results confirm most findings in previous research relating to individual-level variables but also find important associations between contextual factors and marital outcomes. The relative size and sex ratio of an origin group, ethnic diversity, the share of the native-born white population, and the proportion of life that immigrants spent in the United State are all associated with exogamy. These patterns are highly similar across genders and immigrant generations.

Binding sites in the rat brain for Escherichia coli S fimbriae associated with neonatal meningitis.

Escherichia coli strains that cause sepsis and meningitis in neonatal infants carry S fimbriae that bind to sialyl galactoside units of cell surface glycoproteins. To investigate the possible role of S fimbriae in determining the tissue tropism of neonatal meningitis, we have studied the presence of binding sites for S fimbriae in different tissues of the neonatal rat which is susceptible to meningitis caused by S-fimbriated E. coli. Purified S fimbriae were incubated on cryostat sections of different rat organs and their binding was assessed by indirect immunofluorescence. In the brain of the neonatal rat, S fimbriae specifically bound to the luminal surfaces of the vascular endothelium and of the epithelium lining the choroid plexuses and brain ventricles. The binding was completely inhibited by the trisaccharide NeuAc alpha 2-3Gal beta 1-4Glc, a receptor analogue of S fimbriae, and by a preceding neuraminidase treatment of the sections. A recombinant E. coli strain expressing S fimbriae adhered in large numbers to the same tissue sites in the neonatal brain sections as did the purified fimbriae, whereas the non-fimbriated host strain and a recombinant strain expressing P fimbriae did not adhere to brain tissues. The results suggest that adhesion of S-fimbriated bacteria to the binding sites observed in the neonatal brain has a pathogenetic role during bacterial invasion from circulation into the cerebrospinal fluid.