Longitudinal Household Assessment of Respiratory Illness in Children and Parents During the COVID-19 Pandemic.

Importance: In the early COVID-19 pandemic, SARS-CoV-2 testing was only accessible and recommended for symptomatic persons or adults. This restriction hampered assessment of the true incidence of SARS-CoV-2 infection in children as well as detailed characterization of the SARS-CoV-2 disease spectrum and how this spectrum compared with that of other common respiratory illnesses. Objective: To estimate the community incidence of SARS-CoV-2 infection in children and parents and to assess the symptoms and symptom severity of respiratory illness episodes involving SARS-CoV-2-positive test results relative to those with SARS-CoV-2-negative test results. Design, Setting, and Participants: This cohort study randomly selected Dutch households with at least 1 child younger than 18 years. A total of 1209 children and adults from 307 households were prospectively followed up between August 25, 2020, and July 29, 2021, covering the second and third waves of the COVID-19 pandemic. Participation included SARS-CoV-2 screening at 4- to 6-week intervals during the first 23 weeks of participation (core study period; August 25, 2020, to July 29, 2021). Participants in all households finishing the core study before July 1, 2021, were invited to participate in the extended follow-up and to actively report respiratory symptoms using an interactive app until July 1, 2021. At new onset of respiratory symptoms or a SARS-CoV-2 positive test result, a household outbreak study was initiated, which included daily symptom recording, repeated polymerase chain reaction testing (nose-throat swabs and saliva and fecal samples), and SARS-CoV-2 antibody measurement (paired dried blood spots) in all household members. Outbreaks, households, and episodes of respiratory illness were described as positive or negative depending on SARS-CoV-2 test results. Data on participant race and ethnicity were not reported because they were not uniformly collected in the original cohorts and were therefore not representative or informative. Exposures: SARS-CoV-2-positive and SARS-CoV-2-negative respiratory illness episodes. Main Outcomes and Measures: Age-stratified incidence rates, symptoms, and symptom severity for SARS-CoV-2-positive and SARS-CoV-2-negative respiratory illness episodes. Results: Among 307 households including 1209 participants (638 female [52.8%]; 403 [33.3%] aged <12 years, 179 [14.8%] aged 12-17 years, and 627 [51.9%] aged ≥18 years), 183 household outbreaks of respiratory illness were observed during the core study and extended follow-up period, of which 63 (34.4%) were SARS-CoV-2 positive (59 outbreaks [32.2%] during the core study and 4 outbreaks [2.2%] during follow-up). SARS-CoV-2 incidence was similar across all ages (0.24/person-year [PY]; 95% CI, 0.21-0.28/PY). Overall, 33 of 134 confirmed SARS-CoV-2 episodes (24.6%) were asymptomatic. The incidence of SARS-CoV-2-negative respiratory illness episodes was highest in children younger than 12 years (0.94/PY; 95% CI, 0.89-0.97/PY). When comparing SARS-CoV-2-positive vs SARS-CoV-2-negative respiratory illness episodes in children younger than 12 years, no differences were observed in number of symptoms (median [IQR], 2 [2-4] for both groups), symptom severity (median [IQR] maximum symptom severity score, 6 [4-9] vs 7 [6-13]), or symptom duration (median [IQR], 6 [5-12] days vs 8 [4-13] days). However, among adults, SARS-CoV-2-positive episodes had a significantly higher number (median [IQR], 6 [4-8] vs 3 [2-4]), severity (median [IQR] maximum symptom severity score, 15 [9-19] vs 7 [6-11]), and duration (median [IQR] 13 [8-29] days vs 5 [3-11] days; P < .001 for all comparisons) of symptoms vs SARS-CoV-2-negative episodes. Conclusions and Relevance: In this cohort study, during the first pandemic year when mostly partial or full in-person learning occurred, the SARS-CoV-2 incidence rate in children was substantially higher than estimated from routine testing or seroprevalence data and was similar to that of adult household members. Unlike in unvaccinated adults, SARS-CoV-2 symptoms and symptom severity in children were similar to other common respiratory illnesses. These findings may prove useful when developing pediatric COVID-19 vaccine recommendations.

Diet quality in childhood: the Generation R Study.

PURPOSE: We aimed to evaluate diet quality of 8-year-old children in the Netherlands, to identify sociodemographic and lifestyle correlates of child diet quality, and to examine tracking of diet quality from early to mid-childhood. METHODS: For 4733 children participating in a population-based cohort, we assessed dietary intake using a validated food-frequency questionnaire at a median age of 8.1 years (interquartile range 8.0-8.2) (2011-2014). Based on dietary guidelines, we developed and validated a food-based diet quality score for children consisting of ten components (score 0-10): sufficient intake of vegetables; fruit; whole grains; fish; legumes; nuts; dairy; oils and soft fats; and low intake of sugar-containing-beverages; and high-fat and processed meat. RESULTS: We observed a mean (± SD) diet quality score of 4.5 (± 1.2) out of a maximum of 10. On average, intake of legumes, nuts, and oils or soft fats was below recommendations, whereas intake of sugar-containing beverages and high-fat or processed meat was higher than recommended. The main factors associated with higher diet quality were higher maternal educational level (ß = 0.29, 95% CI 0.21, 0.37 versus low education), higher household income (ß = 0.15, 95% CI 0.05, 0.25 versus low income), no maternal smoking (ß = 0.13, 95% CI 0.02, 0.25 versus current smoking), and less screen time (ß = 0.31, 95% CI 0.24, 0.38)-all independent of each other. For children with available dietary data at age 1 year (n = 2608), we observed only weak tracking of diet quality from early to mid-childhood (Pearson's r = 0.19, k = 0.11 for extreme quartiles). CONCLUSION: Overall diet quality of 8-year-old children did not conform to dietary guidelines, especially for children having more screen time, children of lower educated or smoking mothers, or from lower-income households.

Income inequality and social gradients in children's height: a comparison of cohort studies from five high-income countries.

BACKGROUND: Health and well-being are better, on average, in countries that are more equal, but less is known about how this benefit is distributed across society. Height is a widely used, objective indicator of child health and predictor of lifelong well-being. We compared the level and slope of social gradients in children's height in high-income countries with different levels of income inequality, in order to investigate whether children growing up in all socioeconomic circumstances are healthier in more equal countries. METHODS: We conducted a coordinated analysis of data from five cohort studies from countries selected to represent different levels of income inequality (the USA, UK, Australia, the Netherlands and Sweden). We used standardised methods to compare social gradients in children's height at age 4-6 years, by parent education status and household income. We used linear regression models and predicted height for children with the same age, sex and socioeconomic circumstances in each cohort. RESULTS: The total analytic sample was 37 063 children aged 4-6 years. Gradients by parent education and household income varied between cohorts and outcomes. After adjusting for differences in age and sex, children in more equal countries (Sweden, the Netherlands) were taller at all levels of parent education and household income than children in less equal countries (USA, UK and Australia), with the greatest between-country differences among children with less educated parents and lowest household incomes. CONCLUSIONS: The study provides preliminary evidence that children across society do better in more equal countries, with greatest benefit among children from the most disadvantaged socioeconomic groups.

Ethnic background and children's television viewing trajectories: The Generation R Study.

This study, conducted in the Netherlands, evaluated the association between ethnic background and children's TV viewing time at multiple time points and its trajectory. We analyzed 4,833 children with a Dutch, Moroccan, Turkish, or Surinamese ethnic background from the Generation R Study, a population-based study in the Netherlands. Parent-reported television viewing time for children at ages 2, 3, 4, 6, and 9 years was collected by questionnaires sent from April 2004 until January 2015. Odds ratios of watching television ≥1 hour/day at each age were calculated for children from the various ethnic backgrounds. Generalized logistic mixed models (GLMMs) were used to assess the association between ethnic background and television viewing time trajectory. The effect modification by family socioeconomic status was examined in cross-sectional and longitudinal analyses. The percentage of children viewing television ≥1 hour/day increased from age 2 to 9 years for children from all ethnic backgrounds. After adjusting for maternal educational level and net household income, children from all ethnic subgroups had greater odds of watching television ≥1 hour/day at some time points compared with children with a Dutch background (Surinamese: all ages; Moroccan: at ages 4 and 6 years; Turkish: at ages 4 and 9 years). The GLMMs indicated that television viewing trajectories differed between ethnic subgroups. The associations between ethnic background and children's television viewing time were moderated by maternal educational level for child ages 4 and 6 years (p < 0.05). In longitudinal analyses, the ethnic differences in probability of watching television ≥1 hour/day were larger in children from high-educated mothers than in children from low-educated mothers. In conclusion, ethnic differences in television viewing time were present at all measuring time points. The discrepancy between children with a Dutch background and children with another background was larger in high maternal educational subgroups.

Trajectories and predictors of women's health-related quality of life during pregnancy: A large longitudinal cohort study.

The objective of this study was to identify distinct trajectories and their predictors of health-related quality of life (HRQOL) of women during pregnancy in a prospective mother and child cohort. Analyses were based on 3936 Dutch pregnant women in Rotterdam area, the Netherlands. Information on potential predictors was collected in early pregnancy by questionnaire. Latent Class Mixture Modelling and Multinomial Logistic Regression were applied to assess the trajectory and predictors of HRQOL during pregnancy. HRQOL was measured by SF-12 in early, mid- and late pregnancy; physical and mental component summary (PCS-12/MCS-12) scores were calculated. Four physical HRQOL trajectories were identified: a healthy trajectory ('healthy') in 63.3%, consistently low ('vulnerable') in 10.8%; a small increase ('recovering') in 12.8% and a large decrease ('at risk') in 13.1%. Three mental HRQOL trajectories were identified: a healthy trajectory ('healthy') in 86.1%; a large increase ('recovering') in 7.5%; and a large decrease ('at risk') in 6.4%. Compared with healthy trajectories, the likelihood of following the 'vulnerable' physical HRQOL trajectory rather than a healthy trajectory was increased by daily fatigue(OR: 4.82[2.76, 8.40]), pelvic pain (OR:4.76[2.91, 7.78]) and back pain (OR:5.29[3.21, 8.70]); pregnancy-specific anxiety increased the likelihood of following the 'at risk' mental HRQOL trajectory (OR:7.95[4.84, 13.05]). Healthy physical and mental HRQOL trajectories during pregnancy were most common. Predictors indicative of poor HRQOL trajectories included pregnancy-related symptoms and anxiety.

Determinants of organophosphate pesticide exposure in pregnant women: A population-based cohort study in the Netherlands.

BACKGROUND: In the Netherlands organophosphate (OP) pesticides are frequently used for pest control in agricultural settings. Despite concerns about the potential health impacts of low-level OP pesticides exposure, particularly in vulnerable populations, the primary sources of exposure remain unclear. The present study was designed to investigate the levels of DAP metabolites concentrations across pregnancy and to examine various determinants of DAP metabolite concentrations among an urban population of women in the Netherlands. METHOD: Urinary concentrations of six dialkyl phosphate (DAP) metabolites, the main urinary metabolites of OP pesticides, were determined at <18, 18-25, and >25 weeks of pregnancy in 784 pregnant women participating in the Generation R Study (between 2004 and 2006), a large population-based birth cohort in Rotterdam, the Netherlands. Questionnaires administered prenatally assessed demographic and lifestyle characteristics and maternal diet. Linear mixed models, with adjustment for relevant covariates, were used to estimate associations between the potential exposure determinants and DAP metabolite concentrations expressed as molar concentrations divided by creatinine levels. RESULTS: The median DAP metabolite concentration was 311 nmol/g creatinine for the first trimester, 317 nmol/g creatinine for the second trimester, and 310 nmol/g creatinine for the third trimester. Higher maternal age, married/living with a partner, underweight or normal weight (BMI of <18.5 and 18.5-<25), high education, high income, and non-smoking were associated with higher DAP metabolite concentrations, and DAP metabolite concentrations tended to be higher during the summer. Furthermore, fruit intake was associated with increased DAP metabolite concentrations. Each 100 g/d difference in fruit consumption was associated with a 7% higher total DAP metabolite concentration across pregnancy. Other food groups were not associated with higher DAP metabolite concentrations. CONCLUSIONS: The DAP metabolite concentrations measured in the urine of pregnant women in the Netherlands were higher than those in most other studies previously conducted. Fruit intake was the main dietary source of exposure to OP pesticides in young urban women in the Netherlands. The extent to which DAP metabolite concentrations reflect exposure to the active parent pesticide rather than to less toxic metabolites remains unclear. Further research will be undertaken to investigate the possible effects of this relatively high level OP pesticides exposure on offspring health.

Bisphenol and phthalate concentrations and its determinants among pregnant women in a population-based cohort in the Netherlands, 2004-5.

BACKGROUND: Exposure to bisphenols and phthalates in pregnancy may lead to adverse health effects in women themselves and their offspring. OBJECTIVE: To describe first trimester bisphenol and phthalate urine concentrations, including bisphenol and phthalate replacements, and determine nutritional, socio-demographic and lifestyle related determinants. METHODS: In a population-based prospective cohort of 1396 mothers, we measured first trimester bisphenol, phthalate and creatinine urine concentrations (samples collected in 2004-2005, median gestational age 12.9 weeks [inter-quartile range (IQR) 12.1-14.4]). We examined associations of potential determinants with log-transformed bisphenol and phthalate concentrations. Outcomes were back-transformed. Nutritional analyses were performed in a subgroup of 642 Dutch participants only, as the Food Frequency Questionnaire was aimed at Dutch food patterns. RESULTS: Bisphenol A, bisphenol S, and bisphenol F were detected in 79.2%, 67.8% and 40.2% of the population, respectively. Mono-n-butylphthalate, mono-(2-ethyl-5-hydroxyhexyl)phthalate and monobenzylphthalate were detected in > 90% of the population. Nutritional intake was not associated with bisphenol and phthalate concentrations after correction for multiple testing was applied. Obesity was associated with higher high-molecular-weight phthalate concentrations and the lack of folic acid supplement use with higher di-n-octylphthalate concentrations (respective mean differences were 46.73nmol/l [95% CI 14.56-93.72] and 1.03nmol/l [0.31-2.06]). CONCLUSION: Bisphenol S and F exposure was highly prevalent in pregnant women in the Netherlands as early as 2004-5. Although associations of dietary and other key factors with bisphenol and phthalate concentrations were limited, adverse lifestyle factors including obesity and the lack of folic acid supplement use seem to be associated with higher phthalate concentrations in pregnant women. The major limitation was the availability of only one urine sample per participant. However, since phthalates are reported to be quite stable over time, results concerning determinants of phthalate concentrations are expected to be robust.

Socioeconomic differences in children's television viewing trajectory: A population-based prospective cohort study.

We aimed to evaluate the association between family socioeconomic status and repeatedly measured child television viewing time from early childhood to the school period. We analyzed data on 3,561 Dutch children from the Generation R Study, a population-based study in the Netherlands. Parent-reported television viewing time for children aged 2, 3, 4, 6 and 9 years were collected by questionnaires sent from April 2004 until January 2015. Odds ratios of watching television ≥1 hour/day at each age were calculated for children of mothers with low, mid-low, mid-high and high (reference group) education and children from low, middle and high (reference group) income households. A generalized logistic mixed model was used to assess the association between family socioeconomic status and child television viewing time trajectory. The percentage of children watching television ≥1 hour/day increased from age 2 to 9 years for all children (24.2%-85.0% for children of low-educated mothers; 4.7%-61.4% for children of high-educated mothers; 17.2%-74.9% for children from low income households; 6.2%-65.1% for children from high income households). Independent socioeconomic effect in child television viewing time was found for maternal educational level. The interaction between net household income and child age in longitudinal analyses was significant (p = 0.01), indicating that the television viewing time trajectories were different in household income subgroups. However the interaction between maternal educational level and child age was not significant (p = 0.19). Inverse socioeconomic gradients in child television viewing time were found from the preschool period to the late school period. The educational differences between the various educational subgroups remained stable with increasing age, but the differences between household income groups changed over time. Intervention developers and healthcare practitioners need to raise awareness among non-highly educated parents that the socioeconomic gradient in television viewing time has a tracking effect starting from preschool age.

Social inequalities in children's oral health-related quality of life: the Generation R Study.

PURPOSE: Oral health-related quality of life (OHRQoL) is the most important patient-reported outcome measure in oral health research. The purpose of the present research was to study the association of family socioeconomic position (SEP) with children's OHRQoL. METHODS: This cross-sectional study was embedded in the Generation R Study, a population-based cohort study conducted in Rotterdam, The Netherlands. For the present study, OHRQoL was assessed of 3871 ten-year old children. Family SEP was assessed with the following indicators: maternal/paternal education level, maternal/paternal employment status, household income, benefit dependency, and family composition. Linear regression analyses were performed to evaluate the (independent) associations of family SEP indicators with OHRQoL. RESULTS: The median (90% range) OHRQoL score of the participating children was relatively high [50.0 (43.0-53.0)]; however, OHRQoL was consistently lower in children with low family SEP. Positive associations were found for all SEP indicators (p-values <0.05) except maternal employment status and family composition. Benefit dependency, paternal employment, and household income were the most strongly associated with OHRQoL. No family SEP indicator was significantly associated with OHRQoL independent of the other indicators. CONCLUSIONS: Based on the present findings, interventions and policies promoting good oral health and oral well-being should target children from low socioeconomic position. More research is needed, however, to understand the pathways of social inequalities in children's OHRQoL especially for the effects of material resources on subjective oral health measures.

Social inequalities and dental caries in six-year-old children from the Netherlands.

OBJECTIVES: The purpose of our study was to investigate the association of different socioeconomic and sociodemographic factors with dental caries in six-year-old children. Furthermore, we applied a district based approach to explore the distribution of dental caries among districts of low and high socioeconomic position (SEP). METHODS: In our cross-sectional study 5189 six-year-olds were included. This study was embedded in a prospective population-based birth cohort study in Rotterdam, the Netherlands, the Generation R Study. Parental education level, parental employment status, net household income, single parenting, and teenage pregnancy were considered as indicators for SEP. Dental caries was scored on intraoral photographs by using the decayed, missing, and filled teeth (dmft) index. We compared children without caries (dmft=0) to children with mild caries (dmft=1-3) or severe caries (dmft >3). Multinomial logistic regression analyses and binary logistic regression analyses were performed to study the association between SEP and caries, and between district and caries, respectively. RESULTS: Only maternal education level remained significantly associated with mild caries after adjusting for all other SEP-indicators. Paternal educational level, parental employment status, and household income additionally served as independent indicators of SEP in children with severe caries. Furthermore, living in more disadvantaged districts was significantly associated with higher odds of dental caries. CONCLUSION: Dental caries is more prevalent among six-year-old children with a low SEP, which is also visible at the district level. Maternal educational level is the most important indicator of SEP in the association with caries. CLINICAL SIGNIFICANCE: Our results should raise concerns about the existing social inequalities in dental caries and should encourage development of dental caries prevention strategies. New knowledge about the distribution of oral health inequalities between districts should be used to target the right audience for these strategies.

Associations of maternal folic acid supplementation and folate concentrations during pregnancy with foetal and child head growth: the Generation R Study.

PURPOSE: Folic acid supplementation during pregnancy has been associated with a reduced risk of common neurodevelopmental delays in the offspring. However, it is unclear whether low folate status has effects on the developing brain. We evaluated the associations of maternal folic acid supplementation and folate concentrations during pregnancy with repeatedly measured prenatal and postnatal head circumference in the offspring. METHODS: Within a population-based prospective cohort, we measured maternal plasma folate concentrations at approximately 13 weeks of gestation (90 % range 10.5-17.2) and assessed folic acid supplementation by questionnaire (2001-2005). Up to 11 repeated measures of head circumference were obtained during foetal life (20 and 30 weeks of gestation) and childhood (between birth and age 6 years) in 5866 children (2002-2012). RESULTS: In unadjusted models, foetal head growth was 0.006 SD (95 % CI 0.003; 0.009, P < 0.001) faster per week per 1-SD higher maternal folate concentration. After adjustment for confounders, this association was attenuated to 0.004 SD per week (95 % CI 0.000; 0.007, P = 0.02; estimated absolute difference at birth of 2.7 mm). The association was independent of overall foetal growth. No associations were found between maternal folate concentrations and child postnatal head growth. Preconceptional start of folic acid supplementation was associated with larger prenatal head size, but not with prenatal or postnatal head growth. CONCLUSIONS: Our results suggest an independent, modest association between maternal folate concentrations in early pregnancy and foetal head growth. More research is needed to identify whether specific brain regions are affected and whether effects of folate on foetal head growth influence children's long-term functioning.

Ethnic differences in prevalence and risk factors for hypertension in the Suriname Health Study: a cross sectional population study.

BACKGROUND: Limited information is available about the prevalence, ethnic disparities, and risk factors of hypertension within developing countries. We used data from a nationwide study on non-communicable disease (NCD) risk factors to estimate, explore, and compare the prevalence of hypertension overall and in subgroups of risk factors among different ethnic groups in Suriname. METHOD: The Suriname Health Study used the World Health Organization Steps design to select respondents with a stratified multistage cluster sample of households. The overall and ethnic specific prevalences of hypertension were calculated in general and in subgroups of sex, age, marital status, educational level, income status, employment, smoking status, residence, physical activity, body mass index (BMI), and waist circumference (WC). Differences in the prevalence between ethnic subgroups were assessed using the Chi-square test. We used several adjustment models to explore whether the observed ethnic differences were explained by biological, demographic, lifestyle, or anthropometric risk factors. RESULTS: The prevalence of hypertension was 26.2 % (95 % confidence interval 25.1 %-27.4 %). Men had higher mean values for systolic and diastolic blood pressure compared to women. Blood pressure increased with age. The prevalence was highest for Creole, Hindustani, and Javanese and lowest for Amerindians, Mixed, and Maroons. Differences between ethnic groups were measured in the prevalence of hypertension in subcategories of sex, marital status, education, income, smoking, physical activity, and BMI. The major difference in association of ethnic groups with hypertension was between Hindustani and Amerindians. CONCLUSION: The prevalence of hypertension in Suriname was in the range of developing countries. The highest prevalence was found in Creoles, Hindustani, and Javanese. Differences in the prevalence of hypertension were observed between ethnic subgroups with biological, demographic, lifestyle, and anthropometric risk factors. These findings emphasize the need for ethnic-specific research and prevention and intervention programs.

Ethnic differences in prediabetes and diabetes in the Suriname Health Study.

BACKGROUND: Diabetes is increasing worldwide, and information on risk factors to develop targeted interventions is limited. Therefore, we analyzed data of the Suriname Health Study to estimate the prevalence of prediabetes and diabetes. We also explored whether ethnic differences in prediabetes or diabetes risk could be explained by biological, demographic, lifestyle, anthropometric, and metabolic risk factors. METHOD: The study was designed according to the WHO Steps guidelines. Fasting blood glucose levels were measured in 3393 respondents, aged 15-65 years, from an Amerindian, Creole, Hindustani, Javanese, Maroon or Mixed ethnic background. Prediabetes was defined by fasting blood glucose levels between 6.1 and 7.0 mmol/L and diabetes by fasting blood glucose levels ≥7.0 mmol/L or 'self-reported diabetes medication use.' For all ethnicities, we analyzed sex, age, marital status, educational level, income status, employment, smoking status, residence, physical activity, body mass index, waist circumference, hypertension, and the levels of triglyceride, total cholesterol, high-density lipoprotein-cholesterol and low-density lipoprotein-cholesterol. RESULTS: The prevalence of prediabetes was 7.4%, while that of diabetes was 13 0%. From these diabetes cases, 39.6% were not diagnosed previously. No ethnic differences were observed in the prevalence of prediabetes. For diabetes, Hindustanis (23.3%) had twice the prevalence compared to other ethnic groups (4.7-14.2%). The associations of the risk factors with prediabetes or diabetes varied among the ethnic groups. The differences in the associations of ethnic groups with prediabetes or diabetes were partly explained by these risk factors. CONCLUSIONS: The prevalence of diabetes in Suriname is high and most elevated in Hindustanis. The observed variations in risk factors among ethnic groups might explain the ethnic differences between these groups, but follow-up studies are needed to explore this in more depth.

Splitting hair for cortisol? Associations of socio-economic status, ethnicity, hair color, gender and other child characteristics with hair cortisol and cortisone.

The aim of this study was to examine associations of SES and ethnicity with hair cortisol and cortisone and to identify potential child and family characteristics that can assist in choosing covariates and potential confounders for analyses involving hair cortisol and cortisone concentrations. Hair samples were collected in 2484 6-year-old children from the Generation R Study, a prospective cohort in Rotterdam, the Netherlands. Measurements for cortisol and cortisone were used as the outcome in regression analyses. Predictors were SES, ethnicity, hair color and child characteristics such as birthweight, gestational age at birth, BMI, disease, allergy, and medication use. Lower family income, more children to be supported by this income, higher BMI and darker hair color were associated with higher hair cortisol and cortisone levels. Boys also showed higher levels. Ethnicity (Dutch and North European descent) was related to lower levels. High amounts of sun in the month of hair collection was related to higher levels of cortisone only. More recent hair washing was related to lower levels of cortisol and cortisone. Gestational age at birth, birth weight, age, medication use, hair washing frequency, educational level of the mother, marital status of the mother, disease and allergy were not associated with cortisol or cortisone levels. Our results serve as a starting point for choosing covariates and confounders in studies of substantive predictors or outcomes. Gender, BMI, income, the number of persons in a household, ethnicity, hair color and recency of hair washing are strongly suggested to take into account.

BMD Loci Contribute to Ethnic and Developmental Differences in Skeletal Fragility across Populations: Assessment of Evolutionary Selection Pressures.

Bone mineral density (BMD) is a highly heritable trait used both for the diagnosis of osteoporosis in adults and to assess bone health in children. Ethnic differences in BMD have been documented, with markedly higher levels in individuals of African descent, which partially explain disparity in osteoporosis risk across populations. To date, 63 independent genetic variants have been associated with BMD in adults of Northern-European ancestry. Here, we demonstrate that at least 61 of these variants are predictive of BMD early in life by studying their compound effect within two multiethnic pediatric cohorts. Furthermore, we show that within these cohorts and across populations worldwide the frequency of those alleles associated with increased BMD is systematically elevated in individuals of Sub-Saharan African ancestry. The amount of differentiation in the BMD genetic scores among Sub-Saharan and non-Sub-Saharan populations together with neutrality tests, suggest that these allelic differences are compatible with the hypothesis of selective pressures acting on the genetic determinants of BMD. These findings constitute an explorative contribution to the role of selection on ethnic BMD differences and likely a new example of polygenic adaptation acting on a human trait.

Ethnic disparities in maternal obesity and weight gain during pregnancy. The Generation R Study.

OBJECTIVE: To examine ethnic disparities in maternal prepregnancy obesity and gestational weight gain, and to examine to which extent these differences can be explained by socio-demographic, lifestyle and pregnancy related characteristics. METHODS: In a multi-ethnic population-based prospective cohort study among 6444 pregnant women in Rotterdam, the Netherlands, maternal anthropometrics were repeatedly measured throughout pregnancy. Ethnicity, socio-demographic, lifestyle and pregnancy related characteristics were assessed by physical examinations and questionnaires. RESULTS: The prevalence of prepregnancy overweight and obesity was 23.1% among Dutch-origin women. Statistically higher prevalences were observed among Dutch Antillean-origin (40.8%), Moroccan-origin (49.9%), Surinamese-Creole-origin (38.6%) and Turkish-origin (41.1%) women (all p-values <0.05). Only Dutch Antillean-origin, Moroccan-origin, Surinamese-Creole-origin and Turkish-origin women had higher risks of maternal prepregnancy overweight and obesity as compared to Dutch-origin women (p-values <0.05). Socio-demographic and lifestyle related characteristics explained up to 45% of the ethnic differences in body mass index. Compared to Dutch-origin women, total gestational weight gain was lower in all ethnic minority groups, except for Cape Verdean-origin and Surinamese-Creole-origin women (p-values <0.05). Lifestyle and pregnancy related characteristics explained up to 33% and 40% of these associations, respectively. The largest ethnic differences in gestational weight gain were observed in late pregnancy. CONCLUSION: We observed moderate ethnic differences in maternal prepregnancy overweight, obesity and gestational weight gain. Socio-demographic, lifestyle and pregnancy related characteristics partly explained these differences. Whether these differences also lead to ethnic differences in maternal and childhood outcomes should be further studied.

Social Inequalities in Young Children's Meal Skipping Behaviors: The Generation R Study.

BACKGROUND: Regular meal consumption is considered an important aspect of a healthy diet. While ample evidence shows social inequalities in breakfast skipping among adolescents, little is known about social inequalities in breakfast skipping and skipping of other meals among young school-aged children. Such information is crucial in targeting interventions aimed to promote a healthy diet in children. METHODS: We examined data from 4704 ethnically diverse children participating in the Generation R Study, a population-based prospective cohort study in Rotterdam, the Netherlands. Information on family socioeconomic position (SEP), ethnic background, and meal skipping behaviors was assessed by parent-reported questionnaire when the child was 6 years old. Multiple logistic regression analyses were performed to assess the associations of family SEP (educational level, household income, employment status, family composition) and ethnic background with meal skipping behaviors, using high SEP children and native Dutch children as reference groups. RESULTS: Meal skipping prevalence ranged from 3% (dinner) to 11% (lunch). The prevalence of meal skipping was higher among low SEP children and ethnic minority children. Maternal educational level was independently associated with breakfast skipping ([low maternal educational level] OR: 2.21; 95% CI: 1.24,3.94). Paternal educational level was independently associated with lunch skipping ([low paternal educational level] OR: 1.53; 95% CI: 1.06,2.20) and dinner skipping ([mid-high paternal educational level] OR: 0.39; 95% CI: 0.20,0.76). Household income was independently associated with breakfast skipping ([low income] OR: 2.43, 95% CI: 1.40,4.22) and dinner skipping ([low income] OR: 2.44; 95% CI: 1.22,4.91). In general, ethnic minority children were more likely to skip breakfast, lunch, and dinner compared with native Dutch children. Adjustment for family SEP attenuated the associations of ethnic minority background with meal skipping behaviors considerably. CONCLUSION: Low SEP children and ethnic minority children are at an increased risk of breakfast, lunch, and dinner skipping compared with high SEP children and native Dutch children, respectively. Given these inequalities, interventions aimed to promote regular meal consumption, breakfast consumption in particular, should target children from low socioeconomic groups and ethnic minority children. More qualitative research to investigate the pathways underlying social inequalities in children's meal skipping behaviors is warranted.

Reference ranges and determinants of total hCG levels during pregnancy: the Generation R Study.

Human chorionic gonadotropin (hCG) is a pregnancy hormone secreted by the placental synctiotrophoblast cell layer that has been linked to fetal growth and various placental, uterine and fetal functions. In order to investigate the effects of hCG on clinical endpoints, knowledge on reference range (RR) methodology and determinants of gestational hCG levels is crucial. Moreover, a better understanding of gestational hCG physiology can improve current screening programs and future clinical management. Serum total hCG levels were determined in 8195 women participating in the Generation R Study. Gestational age specific RRs using 'ultrasound derived gestational age' (US RRs) were calculated and compared with 'last menstrual period derived gestational age' (LMP RRs) and a model-based RR. We also investigated which pregnancy characteristics were associated with hCG levels. Compared to the US RRs, the LMP RRs were lower, most notably for the median and lower limit levels. No considerable differences were found between RRs calculated in the general population or in uncomplicated pregnancies only. Maternal smoking, BMI, parity, ethnicity, fetal gender, placental weight and hyperemesis gravidarum symptoms were associated with total hCG. We provide gestational RRs for total hCG and show that total hCG values and RR cut-offs during pregnancy vary depending on pregnancy dating methodology. This is likely due to the influence of hCG on embryonic growth, suggesting that ultrasound based pregnancy dating might be less reliable in women with high/low hCG levels. Furthermore, we identify different pregnancy characteristics that influence total hCG levels considerably and should therefore be accounted for in clinical studies.

First-trimester maternal protein intake and childhood kidney outcomes: the Generation R Study.

BACKGROUND: Nutritional exposures during in utero development may have long-lasting consequences for postnatal renal health. Animal studies suggest that specifically maternal dietary protein intake during pregnancy influences childhood kidney function. OBJECTIVE: We examined the associations of total, animal, and vegetable maternal protein intake during pregnancy with kidney volume and function in school-aged children. DESIGN: This study was conducted in 3650 pregnant women and their children who were participating in a population-based cohort study from early life onward. First-trimester energy-adjusted maternal protein intake was assessed with a food-frequency questionnaire. At the child's age of 6 y, we assessed kidney volume, estimated glomerular filtration rate (eGFR) using serum creatinine and cystatin C concentrations, and microalbuminuria using urine albumin:creatinine ratios. RESULTS: First-trimester maternal total protein intake was associated with a higher childhood creatinine-based eGFR (difference: 0.06 mL × min(-1) × 1.73 m(-2); 95% CI: 0.01, 0.12 mL · min(-1) · 1.73 m(-2) per gram of protein intake). This association was mainly driven by vegetable protein intake (0.22 mL × min(-1) × 1.73 m(-2); 95% CI: 0.10, 0.35 mL · min(-1) · 1.73 m(-2) per gram of vegetable protein intake). These associations were not explained by protein intake in early childhood. First-trimester maternal protein intake was not significantly associated with childhood kidney volume, cystatin C-based eGFR, or the risk of microalbuminuria. CONCLUSIONS: Our findings suggest that higher total and vegetable, but not animal, maternal protein intake during the first trimester of pregnancy is associated with a higher eGFR in childhood. Further follow-up studies are needed to investigate whether maternal protein intake in early pregnancy also affects the risk of kidney diseases in later life.

Early origins of ethnic disparities in cardiovascular risk factors.

BACKGROUND: Not much is known about the ethnic differences in cardiovascular risk factors during childhood in European countries. We examined the ethnic differences in childhood cardiovascular risk factors in the Netherlands. METHODS: In a multi-ethnic population-based prospective cohort study, we measured blood pressure, left ventricular mass, and levels of cholesterol, triglyceride and insulin at the median age of 6.2years. RESULTS: As compared to Dutch children, Cape Verdean and Turkish children had a higher blood pressure, whereas Cape Verdean, Surinamese-Creole and Turkish children had higher total-cholesterol levels (p-values<0.05). Turkish children had higher triglyceride levels, but lower insulin levels than Dutch children (p-values<0.05). As compared to Dutch children, only Turkish children had an increased risk of clustering of cardiovascular risk factors (odds ratio: 2.45 (95% confidence interval 1.18, 3.37)). Parental pre-pregnancy factors explained up to 50% of the ethnic differences in childhood risk factors. In addition to these factors, pregnancy and childhood factors and childhood BMI explained up to 50%, 12.5% and 61.1%, respectively. CONCLUSIONS: Our results suggest that compared to Dutch children, Cape Verdean, Surinamese-Creole and Turkish children have an adverse cardiovascular profile. These differences are largely explained by parental pre-pregnancy factors, pregnancy factors and childhood BMI.