Obstetric Interventions Among Native and Migrant Women: The (Over)use of Episiotomy in Portugal.

Objective: Episiotomy, defined as the incision of the perineum to enlarge the vaginal opening during childbirth, is one of the most commonly performed surgical interventions in the world. We aimed to determine if migrant status is associated with episiotomy, and if individual characteristics mediate this association. Methods: We analyzed data from the Bambino study, a national, prospective cohort of migrant and native women giving birth at a public hospital in mainland Portugal between 2017 and 2019. We included all women with vaginal delivery. The association between migrant status and episiotomy was assessed using multivariable multilevel random-effect logistic regression models. We used path analysis to quantify the direct, indirect and total effects of migrant status on episiotomy. Results: Among 3,583 women with spontaneous delivery, migrant parturients had decreased odds of episiotomy, especially those born in Africa, compared to native Portuguese women. Conversely, with instrumental delivery, migrant women had higher odds of episiotomy. Disparities in episiotomy were largely explained by maternity units' factors, and little by maternal and fetal characteristics. Conclusion: Our results suggest non-medically justified differential episiotomy use during childbirth and highlight the importance of developing evidence-based recommendations for episiotomy use in a country with a high frequency of medical interventions during delivery.

Prevalence of Parental Violent Discipline Toward Children: Findings From A Portuguese Population.

Despite recognizing the detrimental impact of parental violence on children's mental and physical health throughout their lives, violence remains an all-too-real part of life for many children around the globe. However, data on the child-reported prevalence of experienced family violence are scarce and primarily based on parental reports. This study aimed to broaden the body of evidence and measure the lifetime prevalence of child-reported experience of violent disciplinary practices perpetrated by parents and to identify its associated sociodemographic and economic factors. We conducted a cross-sectional study using data from 5,281 Generation XXI participants recruited from 2005 to 2006 in Porto, Portugal. Parental disciplinary practices were reported by 7-year-old children using the Parent-Child Conflict Tactics Scale. Pearson's Chi-squared test was used to compare differences in child-reported frequencies of violent disciplinary practices by sociodemographic variables. We observed statistically significant differences in rates of violent disciplinary practices according to the child's and parent's gender. Specifically, fathers exhibited a higher likelihood than mothers to engage in psychological aggression and corporal punishment, while mothers were more prone to engage in severe and very severe physical assault. When fathers were the perpetrators, boys were more inclined than girls to report all forms of violent disciplinary measures, and when mothers were the perpetrators, boys were particularly susceptible to severe and very severe physical assault compared to girls. In our study, children reported being frequently subjected to violent parental disciplinary practices, independently of family socioeconomic background. Children were more likely to experience psychological aggression and corporal punishment if they were born into high-income families, while severe and very severe physical assaults were more common among children whose parents had lower educational levels. National public awareness of the negative effects of violent disciplinary practices is urgently needed, promoting child-friendly and nonviolent approaches to discipline.

Parental infertility and offspring cardiometabolic trajectories: a pooled analysis of three European cohorts.

OBJECTIVE: To assess whether parental infertility is associated with differences in cardiometabolic trajectories in offspring. DESIGN: Pooled observational analysis in three prospective cohorts. SETTING: Three nationwide pregnancy cohorts. PATIENTS: A total of 14,609 singletons from the UK Avon Longitudinal Study of Parents and Children, the Portuguese Geraçao 21, and the Amsterdam Born Children and Their Development study. Each cohort contributed data up to ages 26, 12, and 13 years, respectively. INTERVENTION: Parental infertility is defined as time-to-pregnancy of ≥12 months (n = 1,392, 9.5%). MAIN OUTCOME MEASURES: Trajectories of body mass index (BMI), waist circumference, systolic blood pressure, diastolic blood pressure, low-density lipoprotein cholesterol (LDL-C) level, high-density lipoprotein cholesterol (HDL-C) level, triglycerides level, and glucose level were compared in the offspring of couples with and without infertility. Trajectories were modeled using mixed-effects models with natural cubic splines adjusting for cohort, sex of the offspring, and maternal factors (age, BMI, smoking, educational level, parity, and ethnicity). Predicted levels of cardiometabolic traits up to 25 years of age were compared with parental infertility. RESULTS: Offspring of couples with infertility had increasingly higher BMI (difference in mean predicted levels by age 25 years: 1.09 kg/m2, 95% confidence interval [0.68-1.50]) and suggestively higher diastolic blood pressure at age 25 years (1.21 mmHg [-0.003 to 2.43]). Their LDL-C tended to be higher, and their HDL-C values tended to be lower over time (age: 25 years, LDL-C: 4.07% [-0.79 to 8.93]; HDL-C: -2.78% [-6.99 to 1.43]). At age 17 years, offspring of couples with infertility had higher waist circumference (1.05 cm [0.11-1.99]) and systolic blood pressure (age: 17 years; 0.93 mmHg [0.044-1.81]), but these differences attenuated at later ages. No intergroup differences in triglyceride and glucose level trajectories were observed. Further adjustment for paternal age, BMI, smoking, and educational level, and both parents' histories of diabetes and hypertension in the cohort with this information available (Avon Longitudinal Study of Parents and Children) did not attenuate intergroup differences. CONCLUSION: Offspring of couples with infertility relative to those of fertile couples have increasingly higher BMI over the years, suggestively higher blood pressure levels, and tend to have greater values of LDL-C and lower values of HDL-C with age.

Variation in follow-up for children born very preterm in Europe.

BACKGROUND: Children born very preterm (<32 weeks of gestation) face high risks of neurodevelopmental and health difficulties compared with children born at term. Follow-up after discharge from the neonatal intensive care unit is essential to ensure early detection and intervention, but data on policy approaches are sparse. METHODS: We investigated the characteristics of follow-up policy and programmes in 11 European countries from 2011 to 2022 using healthcare informant questionnaires and the published/grey literature. We further explored how one aspect of follow-up, its recommended duration, may be reflected in the percent of parents reporting that their children are receiving follow-up services at 5 years of age in these countries using data from an area-based cohort of very preterm births in 2011/12 (N = 3635). RESULTS: Between 2011/12 and 22, the number of countries with follow-up policies or programmes increased from 6 to 11. The policies and programmes were heterogeneous in eligibility criteria, duration and content. In countries that recommended longer follow-up, parent-reported follow-up rates at 5 years of age were higher, especially among the highest risk children, born <28 weeks' gestation or with birthweight <1000 g: between 42.1% and 70.1%, vs. <20% in most countries without recommendations. CONCLUSIONS: Large variations exist in follow-up policies and programmes for children born very preterm in Europe; differences in recommended duration translate into cross-country disparities in reported follow-up at 5 years of age.

Prediction of movement difficulties at 5 years from parent report at 2 years in children born extremely preterm.

AIM: To assess the predictive validity of parent-reported gross motor impairment (GMI) at age 2 years to detect significant movement difficulties at age 5 years in children born extremely preterm. METHOD: Data were from 556 children (270 males, 286 females) born at less than 28 weeks' gestation in 2011 to 2012 in 10 European countries. Parent report of moderate/severe GMI was defined as walking unsteadily or unable to walk unassisted at 2 years corrected age. Examiners assessed significant movement difficulties (score ≤ 5th centile on the Movement Assessment Battery for Children, Second Edition) and diagnoses of cerebral palsy (CP) were collected by parent report at 5 years chronological age. RESULTS: At 2 years, 66 (11.9%) children had moderate/severe GMI. At 5 years, 212 (38.1%) had significant movement difficulties. Parent reports of GMI at age 2 years accurately classified CP at age 5 years in 91.0% to 93.2% of children. Classification of moderate/severe GMI at age 2 years had high specificity (96.2%; 95% confidence interval 93.6-98.0) and positive predictive value (80.3%; 68.7-89.1) for significant movement difficulties at age 5 years. However, 74.5% of children with significant movement difficulties at 5 years were not identified with moderate/severe GMI at age 2 years, resulting in low sensitivity (25.1%; 19.4-31.5). INTERPRETATION: This questionnaire may be used to identify children born extremely preterm who at age 2 years have a diagnosis of CP or movement difficulties that are likely to have a significant impact on their functional outcomes at age 5 years.

Component-resolved diagnosis in childhood and prediction of asthma in early adolescence: A birth cohort study.

INTRODUCTION: Component-resolved diagnosis (CRD) has been decisive in exploring the mechanisms of IgE sensitization, but the predictive ability to detect asthma has not been addressed. We aim to develop and evaluate the performance of a personalized predictive algorithm for asthma that integrates information on allergic sensitization using CRD. METHODS: One thousand one hundred one twenty-five children from the Generation XXI birth cohort were randomly selected to perform a screening test for allergic sensitization and a subsample was characterized using CRD against 112 allergen components. Allergen components were analyzed using volcano plots and partial least squares (PLS) analysis. Logistic regression was performed to assess the associations between the obtained latent components (LC) and allergic outcomes (asthma, rhinitis, eczema) including other potential predictors used in previous asthma risk scores. The accuracy of the model in predicting asthma was assessed using Receiver Operating Characteristic (ROC) curve statistics. RESULTS: In the PLS, the first LC was positively associated with asthma, rhinitis, and eczema. This LC was mainly driven by positive weights for Der p 1/2/23, Der f 1/2, and Fel d 1. The main components in the second LC were pollen and food allergens. History of early wheezing and parental allergy were included in the predictive model and the area under the curve improved to 0.82. CONCLUSIONS: This is the first approach to improve the clinical applicability of CRD by combining CRD and clinical data to predict asthma at 13 years. Sensitization to distinct allergen molecules seems relevant to improve the accuracy of asthma prediction models.

Incarceration history is associated with HIV infection among community-recruited people who inject drugs in Europe: A propensity-score matched analysis of cross-sectional studies.

AIMS: We measured the association between a history of incarceration and HIV positivity among people who inject drugs (PWID) across Europe. DESIGN, SETTING AND PARTICIPANTS: This was a cross-sectional, multi-site, multi-year propensity-score matched analysis conducted in Europe. Participants comprised community-recruited PWID who reported a recent injection (within the last 12 months). MEASUREMENTS: Data on incarceration history, demographics, substance use, sexual behavior and harm reduction service use originated from cross-sectional studies among PWID in Europe. Our primary outcome was HIV status. Generalized linear mixed models and propensity-score matching were used to compare HIV status between ever- and never-incarcerated PWID. FINDINGS: Among 43 807 PWID from 82 studies surveyed (in 22 sites and 13 countries), 58.7% reported having ever been in prison and 7.16% (n = 3099) tested HIV-positive. Incarceration was associated with 30% higher odds of HIV infection [adjusted odds ratio (aOR) = 1.32, 95% confidence interval (CI) = 1.09-1.59]; the association between a history of incarceration and HIV infection was strongest among PWID, with the lowest estimated propensity-score for having a history of incarceration (aOR = 1.78, 95% CI = 1.47-2.16). Additionally, mainly injecting cocaine and/or opioids (aOR = 2.16, 95% CI = 1.33-3.53), increased duration of injecting drugs (per 8 years aOR = 1.31, 95% CI = 1.16-1.48), ever sharing needles/syringes (aOR = 1.91, 95% CI = 1.59-2.28) and increased income inequality among the general population (measured by the Gini index, aOR = 1.34, 95% CI = 1.18-1.51) were associated with a higher odds of HIV infection. Older age (per 8 years aOR = 0.84, 95% CI = 0.76-0.94), male sex (aOR = 0.77, 95% CI = 0.65-0.91) and reporting pharmacies as the main source of clean syringes (aOR = 0.72, 95% CI = 0.59-0.88) were associated with lower odds of HIV positivity. CONCLUSIONS: A history of incarceration appears to be independently associated with HIV infection among people who inject drugs (PWID) in Europe, with a stronger effect among PWID with lower probability of incarceration.

The influence of the Great Recession on perinatal health-an ecological study on the trend changes and regional differences in Portugal.

Background: Few studies examine the relationship between socioeconomic factors and trends in mortality in high-income European countries. Due to the lack of regional-level data, most recent studies on social inequality in Portugal do not investigate regional differences. This study analyses time trends and regional disparities in the evolution of perinatal mortality (PMR) and infant mortality (IMR) associated with demographic and socioeconomic indicators following Portugal's 2008 economic and financial crisis. Methods: Associations were assessed using generalised linear models. A Poisson joinpoint regression model was applied to identify relevant PMR and IMR changes between 2000 and 2018. Country regional disparities were analysed using Mixed Effect Multilevel models. Findings: IMR and PMR significantly decreased in the pre-crisis period but not in the post-crisis period. The significant differences between regions in IMR and PMR in 2000 were followed by a different evolution of regional IMR after 2008. PMR and IMR were not significantly associated with socioeconomic indicators. A significant positive association with maternal age at first birth was identified. Interpretation: Results confirm the influence of the crisis on PMR and IMR trends in Portugal, taking into account recurring associations between macroeconomic cycles, variations in mortality trends, macroeconomic volatility, and stagnation of IMR and PMR. Regional inequalities confirm the internal variability of the crisis influence and persistent spatial inequalities affecting IMR patterns. Funding: FCT, under the Institute of Public Health of the University of Porto (ISPUP)-EPIUnit (UIDB/04750/2020) and ITR (LA/P/0064/2020), Maastricht University's external PhD programme under the Care and Public Health Research Institute (CAPHRI), and the RECAP preterm project (grant agreement no 733280).

Development and validation of predictive equations for spirometry in Portuguese children.

Background: There are no data on lung function reference values for Portuguese children, and the contribution from the Portuguese data set in the Global Lung Function Initiative (GLI) is scant. Objectives: We aimed to estimate new up-to-date reference values for Portuguese children by fitting a multivariable regression model to a general population sample. Further, we intended to assess the external validity of the obtained reference values and to compare them to the GLI reference values. Methods: A random sample of 858 children from 20 primary schools were screened by health questionnaire, physical examination, and spirometry. Spirometric parameters recorded were FVC, FEV1, and FEF25-75. Multiple regression models were used to derive reference equations. Results: Overall, 481 children, aged between 7 and 12 years, 267 boys (55.5%), were included. Boys had higher values for FVC and FEV1 than girls (P < .05). The strongest correlation was found for FVC with height (r = 0.71 for boys and 0.70 for girls), while the lowest correlation was observed in both sexes for FEF25-75 with age (r = 0.23). Height was the most significant predictor of FVC, FEV1, and FEF25-75 in our models. Weight and body mass index were not significant predictors for boys but had a significant effect on girls' equations for all spirometry parameters. Compared to obtained reference equations with GLI, they performed better for FVC in boys, FEV1 in girls, and FEF25-75 in both boys and girls. Conclusion: We offer up-to-date reference values of spirometry for Portuguese children that can be used in clinical practice and research.

The Association between Childhood Obesity and Cardiovascular Changes in 10 Years Using Special Data Science Analysis.

The increasing prevalence of overweight and obesity is a worldwide problem, with several well-known consequences that might start to develop early in life during childhood. The present research based on data from children that have been followed since birth in a previously established cohort study (Generation XXI, Porto, Portugal), taking advantage of State-of-the-Art (SoA) data science techniques and methods, including Neural Architecture Search (NAS), explainable Artificial Intelligence (XAI), and Deep Learning (DL), aimed to explore the hidden value of data, namely on electrocardiogram (ECG) records performed during follow-up visits. The combination of these techniques allowed us to clarify subtle cardiovascular changes already present at 10 years of age, which are evident from ECG analysis and probably induced by the presence of obesity. The proposed novel combination of new methodologies and techniques is discussed, as well as their applicability in other health domains.

A double-edged sword: Residents' views on the health consequences of gentrification in Porto, Portugal.

Gentrification is currently shaping the urban environment in important ways. It also contributes to shaping the health of the inhabitants of gentrifying cities, although it is still unclear how. Gentrification processes are often linked to different drivers and have specific local translations, further complicating the study of the relationship between gentrification and health. We investigated this relationship in Porto, Portugal, a southern European city undergoing rampant transnational gentrification. In order to study how gentrification impacts health from the point of view of that city's residents, we conducted a study using photovoice with a sample of participants recruited from a population-based cohort, which was divided into three different groups: one from gentrifying areas of Porto, another from deprived non-gentrifying areas, and the other from affluent areas. The thematic analysis of data generated six themes, each referring to a change, or a set of connected changes, related to gentrification: increasing floating population, lack of housing access and displacement, construction and rehabilitation, changing local commerce, loss of place, and broader socioeconomic change. According to the accounts from participants, these changes affect health in different ways, both beneficial and harmful. Participants also reflected on how to act on this issue. This research adds to the knowledge about the relationship between gentrification and health by providing detailed and nuanced views about this relationship considering its city-wide impacts.

The contribution to policies of an exposome-based approach to childhood obesity.

Childhood obesity is an increasingly severe public health problem, with a prospective impact on health. We propose an exposome approach to identify actionable risk factors for this condition. Our assumption is that relationships between external exposures and outcomes such as rapid growth, overweight, or obesity in children can be better understood through a "meet-in-the-middle" model. This is based on a combination of external and internal exposome-based approaches, that is, the study of multiple exposures (in our case, dietary patterns) and molecular pathways (metabolomics and epigenetics). This may strengthen causal reasoning by identifying intermediate markers that are associated with both exposures and outcomes. Our biomarker-based studies in the STOP consortium suggest (in several ways, including mediation analysis) that branched-chain amino acids (BCAAs) could be mediators of the effect of dietary risk factors on childhood overweight/obesity. This is consistent with intervention and animal studies showing that higher intake of BCAAs has a positive impact on body composition, glycemia, and satiety. Concerning food, of particular concern is the trend of increasing intake of ultra-processed food (UPF), including among children. Several mechanisms have been proposed to explain the impact of UPF on obesity and overweight, including nutrient intake (particularly proteins), changes in appetite, or the role of additives. Research from the Avon Longitudinal Study of Parents and Children cohort has shown a relationship between UPF intake and trajectories in childhood adiposity, while UPF was related to lower blood levels of BCAAs. We suggest that an exposome-based approach can help strengthening causal reasoning and support policies. Intake of UPF in children should be restricted to prevent obesity.

Measuring the clustering effect of the SARS-CoV-2 transmission in a school population: a cross-sectional study in a high incidence region.

Since the beginning of the pandemic, there has been a great deal of controversy regarding the role of schools in the spread of SARS-CoV-2 infection, and the relative contribution of students, teachers, and others. To quantify the clustering effect of SARS-CoV-2 infection within classes and schools considering the seroprevalence of specific antibodies among students and school staff (teachers and non-teachers) evaluated in schools located in the Northern region of Portugal. 1517 individuals (1307 students and 210 school staff) from 4 public and 2 private schools, comprising daycare to secondary levels, were evaluated. A rapid point-of-care test for SARS-CoV-2 specific IgM and IgG antibodies was performed and a questionnaire was completed providing sociodemographic and clinical information. We calculated the seroprevalence of IgM and IgG antibodies and estimated the Median Odds Ratio (OR) and 95% confidence interval (CI) to assess the clustering effect, using a multilevel (school and class) logistic regression. SARS-CoV-2 seroprevalence (IgM or IgG) was 21.8% and 23.8% (p = 0.575) in students and school staff, respectively. A total of 84 (8.6%) students and 35 (16.7%) school staff reported a previous molecular diagnosis. Among students, those who reported high-risk contacts only at school (OR = 1.13; 95% CI 0.72-1.78) had a seroprevalence similar to those without high-risk contacts; however, seroprevalence was significantly higher among those who only reported a high-risk contact outside the school (OR = 6.56; 95% CI 3.68-11.72), or in both places (OR = 7.83; 95% CI 5.14-11.93). Similar associations were found for school staff. The median OR was 1.00 (95% CI 1.00, 1.38) at the school-level and 1.78 (95% CI 1.40, 2.06) at the class-level. SARS-CoV-2 seroprevalence was similar between students and staff, without a clustering effect observed at the school level, and only a moderate clustering effect documented within classes. These results indicate that the mitigation measures in the school environment can prevent the spread of class outbreaks to the remaining school community.

Sensitization trajectories to multiple allergen components in a population-based birth-cohort.

BACKGROUND: The characteristics of allergic sensitization profiles can differ between populations and geographic regions, contributing differently to the association with allergic diseases. Consequently, the sensitization trajectories found in previous studies conducted in Northern Europe may not apply in Southern European countries. OBJECTIVE: To identify trajectories of allergic sensitization profiles during childhood and evaluate the association with allergic outcomes, using data from a Portuguese birth cohort. METHODS: A random sample from Generation XXI was screened for allergic sensitization at 10 years of age. Among 452 allergic sensitized children, 186 were tested with ImmunoCAP™ ISAC multiplex array that detects 112 molecular components, at three follow-ups (4, 7, and 10 years old). Information on allergic outcomes (asthma, rhinitis, atopic dermatitis) was obtained at the 13-year-old follow-up. Latent class analysis (LCA) was used to identify clusters of participants with similar sensitization profiles. Then, sensitization trajectories were defined based on the most prevalent transitions between clusters over time. Logistic regression was applied to estimate the association between sensitization trajectories and allergic diseases. RESULTS: Five trajectories were proposed: "no/few sensitizations," "early persistent house dust mites (HDM)," "early HDM and persistent/late grass pollen," "late grass pollen," and "late HDM." The "early HDM and persistent/late grass pollen" trajectory was associated with rhinitis and "early persistent HDM" with asthma and rhinitis. CONCLUSION: Distinct sensitization trajectories pose different risks in the development of allergic diseases. These trajectories present some differences from those in Northern European countries and are important for planning adequate prevention health plans.

Using Digital Tools to Study the Health of Adults Born Preterm at a Large Scale: e-Cohort Pilot Study.

BACKGROUND: Preterm birth is a global health concern. Its adverse consequences may persist throughout the life course, exerting a potentially heavy burden on families, health systems, and societies. In high-income countries, the first children who benefited from improved care are now adults entering middle age. However, there is a clear gap in the knowledge regarding the long-term outcomes of individuals born preterm. OBJECTIVE: This study aimed to assess the feasibility of recruiting and following up an e-cohort of adults born preterm worldwide and provide estimations of participation, characteristics of participants, the acceptability of questions, and the quality of data collected. METHODS: We implemented a prospective, open, observational, and international e-cohort pilot study (Health of Adult People Born Preterm-an e-Cohort Pilot Study [HAPP-e]). Inclusion criteria were being an adult (aged ≥18 years), born preterm (<37 weeks of gestation), having internet access and an email address, and understanding at least 1 of the available languages. A large, multifaceted, and multilingual communication strategy was established. Between December 2019 and June 2021, inclusion and repeated data collection were performed using a secured web platform. We provided descriptive statistics regarding participation in the e-cohort, namely, the number of persons who registered on the platform, signed the consent form, initiated and completed the baseline questionnaire, and initiated and completed the follow-up questionnaire. We also described the main characteristics of the HAPP-e participants and provided an assessment of the quality of the data and the acceptability of sensitive questions. RESULTS: As of December 31, 2020, a total of 1004 persons had registered on the platform, leading to 527 accounts with a confirmed email and 333 signed consent forms. A total of 333 participants initiated the baseline questionnaire. All participants were invited to follow-up, and 35.7% (119/333) consented to participate, of whom 97.5% (116/119) initiated the follow-up questionnaire. Completion rates were very high both at baseline (296/333, 88.9%) and at follow-up (112/116, 96.6%). This sample of adults born preterm in 34 countries covered a wide range of sociodemographic and health characteristics. The gestational age at birth ranged from 23+6 to 36+6 weeks (median 32, IQR 29-35 weeks). Only 2.1% (7/333) of the participants had previously participated in a cohort of individuals born preterm. Women (252/333, 75.7%) and highly educated participants (235/327, 71.9%) were also overrepresented. Good quality data were collected thanks to validation controls implemented on the web platform. The acceptability of potentially sensitive questions was excellent, as very few participants chose the "I prefer not to say" option when available. CONCLUSIONS: Although we identified room for improvement in specific procedures, this pilot study confirmed the great potential for recruiting a large and diverse sample of adults born preterm worldwide, thereby advancing research on adults born preterm.

Towards a consensus definition of allostatic load: a multi-cohort, multi-system, multi-biomarker individual participant data (IPD) meta-analysis.

BACKGROUND: Allostatic load (AL) is a multi-system composite index for quantifying physiological dysregulation caused by life course stressors. For over 30 years, an extensive body of research has drawn on the AL framework but has been hampered by the lack of a consistent definition. METHODS: This study analyses data for 67,126 individuals aged 40-111 years participating in 13 different cohort studies and 40 biomarkers across 12 physiological systems: hypothalamic-pituitary-adrenal (HPA) axis, sympathetic-adrenal-medullary (SAM) axis, parasympathetic nervous system functioning, oxidative stress, immunological/inflammatory, cardiovascular, respiratory, lipidemia, anthropometric, glucose metabolism, kidney, and liver. We use individual-participant-data meta-analysis and exploit natural heterogeneity in the number and type of biomarkers that have been used across studies, but a common set of health outcomes (grip strength, walking speed, and self-rated health), to determine the optimal configuration of parameters to define the concept. RESULTS: There was at least one biomarker within 9/12 physiological systems that was reliably and consistently associated in the hypothesised direction with the three health outcomes in the meta-analysis of these cohorts: dehydroepiandrosterone sulfate (DHEAS), low frequency-heart rate variability (LF-HRV), C-reactive protein (CRP), resting heart rate (RHR), peak expiratory flow (PEF), high density lipoprotein cholesterol (HDL-C), waist-to-height ratio (WtHR), HbA1c, and cystatin C. An index based on five biomarkers (CRP, RHR, HDL-C, WtHR and HbA1c) available in every study was found to predict an independent outcome - mortality - as well or better than more elaborate sets of biomarkers. DISCUSSION: This study has identified a brief 5-item measure of AL that arguably represents a universal and efficient set of biomarkers for capturing physiological 'wear and tear' and a further biomarker (PEF) that could usefully be included in future data collection.

Correction: Gestational age at birth and body size from infancy through adolescence: An individual participant data meta-analysis on 253,810 singletons in 16 birth cohort studies.

[This corrects the article DOI: 10.1371/journal.pmed.1004036.].

Sleep patterns in childhood: a longitudinal assessment from the Generation XXI birth cohort.

OBJECTIVE: To describe sleep-wake patterns in young children, based on sleep characteristics in early infancy and preschool ages, identifying their main sociodemographic characteristics, and to assess the association between different sleep characteristics at both ages. METHOD: We included 1092 children from the Generation XXI birth cohort, evaluated at six months and four years of age, by face-to-face interviews. Sleep patterns were constructed through latent class analysis and structured equation modeling, including data on wake-up time and bedtime, afternoon naps, locale of nighttime sleep and night awakenings. To estimate the association between sociodemographic characteristics and sleep patterns, odds ratios and 95% confidence intervals were computed using logistic regression. RESULTS: Two sleep patterns were identified through latent class analysis: pattern 1 was characterized by earlier bedtime and wake-up times, while pattern 2 was defined by later times. When compared with pattern 1, pattern 2 was more frequent among children whose mothers had changed from partnered to not partnered until preschool age and those who did not stay at the kindergarten, and was less common among those with siblings. Through structured equation modeling, an aggregating factor was identified at preschool age, which was mainly correlated with bedtime and wake-up time. A positive association between sleep characteristics evaluated in early infancy and in preschool ages was observed. CONCLUSIONS: Sleep patterns and circadian sleep preferences seem to be developed early in life, which highlight the importance of promoting an adequate sleep hygiene from infancy, assuming its impact on sleep quality during the life course.