Associations of birth order with early growth and adolescent height, body composition, and blood pressure: prospective birth cohort from Brazil

Sibship Composition and BMI Z-Score Among Saudi Preschoolers: A Cross-Sectional Study

Background and objective The association between sibship composition and child body mass index (BMI) has not been investigated in any Arab/Middle Eastern populations. In light of this, this study aimed to examine the association of the number of siblings, number of older siblings, and number of younger siblings with child BMI z-score (BMIz) among preschoolers in the Kingdom of Saudi Arabia (KSA). Methods A total of 209 mothers and their children were recruited from preschools in Jeddah, KSA. Mothers reported their responses to the study questionnaire via telephone. Child anthropometry was objectively measured; BMIz was calculated based on age- and sex-specific World Health Organization (WHO) growth standards and reference data. We used hierarchical multiple linear regression to examine the association between sibship composition variables and child BMIz, independent of the effect of potential confounders, and to evaluate changes in model fit. Results The number of siblings was negatively associated with child BMIz [b = -0.18, 95% confidence interval (CI) = -0.35, -0.06, p<0.01, adjusted R2 = 0.16]. There was a negative association between the number of older siblings and child BMIz (b = -0.23, 95% CI = -0.38, -0.11, p<0.01, adjusted R2 = 0.21) as well as between the number of older sisters and child BMIz (b = -0.18, 95% CI = -0.52, -0.09, p<0.01, adjusted R2 = 0.19). However, there were no significant associations between the number of older brothers or the number of younger siblings and child BMIz. Conclusions Based on our findings, sibship composition was found to be associated with BMIz among a sample of preschoolers in KSA. More research is needed to further establish this association and to understand the underlying mechanism of the association of the greater number of older siblings and older sisters with lower BMIz.

Differential gene expression in two consecutive pregnancies between same sex siblings and implications on maternal constraint

The objective of this study was to investigate how placental gene expression differs in two consecutive pregnancies in same sex siblings, and its possible association with the "maternal constraint" hypothesis. Material was gathered from the BASIC study (Biological, Affect, Stress, Imaging, and Cognition in Pregnancy and the Puerperium), a population based prospective study that was started in 2009 in Uppsala. Over 900 specimens of placenta biopsies were collected and out of these 10 women gave birth twice, to the same sex child, and were included in this study. The total RNA was isolated and prepared from frozen villous tissue from the placenta and further analyzed by use of Ion AmpliSeq Human Transcriptome Gene Expression kit. A total of 234 genes differed significantly between the first and second pregnancy placentas, when adjusting for delivery mode, maternal BMI and gestational age. Of special interest was the down-regulated group of genes in the second pregnancy. Exemplified by Pentraxin 3, SRY-Box Transcription Factor 9, and Serum Amyloid A1, which all were associated with biological processes involved in the immune system and inflammation. Further, protein-protein interaction analysis visualized them as hub genes interacting with several of the other differentially expressed genes. How these altered gene expressions affect maternal constraint during pregnancy needs further validation in lager study cohorts and also future validation in functional assays.

A Pregnancy and Childhood Epigenetics Consortium (PACE) meta-analysis highlights potential relationships between birth order and neonatal blood DNA methylation

Higher birth order is associated with altered risk of many disease states. Changes in placentation and exposures to in utero growth factors with successive pregnancies may impact later life disease risk via persistent DNA methylation alterations. We investigated birth order with Illumina DNA methylation array data in each of 16 birth cohorts (8164 newborns) with European, African, and Latino ancestries from the Pregnancy and Childhood Epigenetics Consortium. Meta-analyzed data demonstrated systematic DNA methylation variation in 341 CpGs (FDR adjusted P < 0.05) and 1107 regions. Forty CpGs were located within known quantitative trait loci for gene expression traits in blood, and trait enrichment analysis suggested a strong association with immune-related, transcriptional control, and blood pressure regulation phenotypes. Decreasing fertility rates worldwide with the concomitant increased proportion of first-born children highlights a potential reflection of birth order-related epigenomic states on changing disease incidence trends.

Relationship between Birth Order and Postnatal Growth until 4 Years of Age: The Japan Environment and Children’s Study

Later-borns tend to be shorter than first-borns in childhood and adulthood. However, large-scale prospective studies examining growth during infancy according to birth order are limited. We aimed to investigate the relationship between birth order and growth during the first 4 years of life in a Japanese prospective birth cohort study. A total of 26,249 full-term singleton births were targeted. General linear and multivariable logistic regression models were performed and adjusted for birth weight, parents’ heights, maternal age at delivery, gestational weight gain, maternal smoking and alcohol drinking status during pregnancy, household income, breastfeeding status, and Study Areas. The multivariate adjusted mean length Z-scores in “first-borns having no sibling”, “first-borns having siblings”, “second-borns”, and “third-borns or more” were −0.026, −0.013, 0.136, and 0.120 at birth and −0.324, −0.330, −0.466, and −0.569 at 10 months, respectively. Results similar to those at 10 months were observed at 1.5, 3, and 4 years. The adjusted odds ratios (95% confidence intervals) of short stature at 4 years in “first-borns having siblings”, “second-borns”, and “third-borns or more” were 1.08 (0.84–1.39), 1.36 (1.13–1.62), and 1.50 (1.20–1.88), respectively, versus “first-borns having no sibling”. Birth order was significantly associated with postnatal growth and may be a factor predisposing to short stature in early childhood.

Is only-child status associated with a higher blood pressure in adolescence? An observational study

Growing up with siblings may affect quality of life as well as hemodynamic parameters including blood pressure. Using weighted data from the nationwide and representative German KiGGs study, we assessed the relationship between only-child status, birth order, and arterial blood pressure in a cohort of 7311 adolescents aged between 11 and 17 years. Our data showed that only-children had the highest mean arterial blood pressure (87.3 ± 8.4 mmHg) as compared to first-born (86.3 ± 8.0), middle-born (86.4 ± 8.7), and youngest-born siblings (86.6 ± 8.2; p = 0.012). The two groups of only-children and first-borns differed significantly with respect to their age- and sex-specific, z-scored data for systolic (p = 0.047), diastolic (p = 0.012), and mean arterial blood pressure (p = 0.005). Linear regression models with blood pressure recordings as dependent variable adjusted to age, migration background, and age- and sex-specific z-scores of body-mass index confirmed that only-child status was an independent predictor of a higher diastolic blood pressure (p = 0.037). A similar result was observed for mean arterial blood pressure (p = 0.033), whereas systolic blood pressure was not associated with only-children status (p = 0.258).   Conclusion: In summary, we found a significant and positive relationship between only-child status and blood pressure, with the highest recordings in only-children and the lowest in first-borns. Models adjusted for relevant clinical confounders demonstrated slightly higher blood pressure in only-children compared to first-borns, who are both in an alpha birth order. Although these blood pressure differences were statistically significant, they have limited, if any, clinical meaning in this age group. What is Known: • In children and adults, blood pressure is significantly higher in only-children compared to children with siblings. However, it is unclear whether there are also similar blood pressure differences in adolescents and between only-children and first-borns. What is New: • Among adolescents in the alpha birth order, growing up as an only-child is associated with significantly higher mean blood pressure than among first-borns living with younger siblings.

Health outcomes of only children across the life course: An investigation using Swedish register data

Only children (with no full biological siblings) are a growing subgroup in many high-income settings. Previous studies have largely focused on the short-term developmental outcomes of only children, but there is limited evidence on their health outcomes. Using Swedish population register data for cohorts born 1940-75, we compare the health of only children with that of children from multi-child sibling groups, taking into account birth order, family size, and presence of half-siblings. Only children showed lower height and fitness scores, were more likely to be overweight/obese in late adolescence, and experienced higher later-life mortality than those with one or two siblings. However, only children without half-siblings were consistently healthier than those with half-siblings, suggesting that parental disruption confers additional disadvantages. The health disadvantage was attenuated but not fully explained by adjustment for parental characteristics and after using within-family maternal cousin comparison designs.

Exploring the Associations between Single-Child Status and Childhood High Blood Pressure and the Mediation Effect of Lifestyle Behaviors

Background: This study aimed to assess the association between single-child status and childhood high blood pressure (HBP) and to explore the role of lifestyle behaviors in this relationship. Methods: This study used data from a cross-sectional survey of 50,691 children aged 7~18 years in China. Linear and logistic regression models were used to assess the relationship between single-child status and HBP, and interactions between single-child status and lifestyle behaviors were also evaluated. Mediation analysis was conducted to detect the mediation effect of lifestyle behaviors. Results: Of the participants enrolled, 67.2% were single children and 49.4% were girls. Non-single children were associated with a greater risk of HBP, especially in girls (OR = 1.11, 95%CI: 1.03~1.19). Meat consumption and sedentary behavior mediated 58.9% of the association between single-child status and HBP (p < 0.01). When stratified by sleeping duration, non-single girls of insufficient sleep and hypersomnia showed a higher risk of HBP (p < 0.05) than single-child peers, but not in those with adequate sleep. Conclusion: Findings suggest that non-single children had an increased risk of HBP, and keeping healthy lifestyle behaviors could help to mitigate the adverse impact in non-single children.

Sex Differences in the Association of Sibship Size and Position in Sibship with Lipid Profile during Adolescence: A Cross-Sectional Study

BACKGROUND

Epidemiologic studies have reported associations of sibship size and position of the child in the sibship with multiple health outcomes, including adiposity and diabetes. However, little is known about sibling effects on lipids. Hence, this study sought to evaluate associations of the number of total, older, and younger siblings with lipid profile among adolescents.

METHODS

In a cross-sectional study among high school students aged 14 to 19 years, lipid levels were measured in capillary blood. Parents reported the number of siblings (total, older, and younger). Geometric means of lipids were calculated, and linear regression was used to estimate the ratio of geometric means (RoGM) and 95% confidence intervals (CI). Analyses were sex stratified.

RESULTS

Of the total study sample (n = 1,584), 758 (47.9%) were boys and 826 (52.1%) were girls, with median age of 16.0 years. Total cholesterol (TC) was lower by 8% (adjusted-RoGM = 0.92, 95% CI: 0.88-0.96) among boys with ≥3 older siblings compared to those with no older siblings. Similarly, boys with ≥3 younger sibling compared to those with no younger siblings had reduced TC by 7% (adjusted-RoGM = 0.93, 0.87-0.99). Moreover, an increased number of total siblings (≥4 vs. 0/1: adjusted-RoGM = 0.80, 0.67-97) and older siblings (≥3 vs. 0: adjusted-RoGM = 0.90, 0.82-0.98) were associated with reduced low-density lipoprotein cholesterol (LDL-C) among boys. Similarly, lower levels of triglycerides (TG) were seen among boys with ≥3 older siblings compared to those with no older siblings (adjusted-RoGM = 0.87, 0.78-0.96). A higher number of younger siblings was associated with increased high-density lipoprotein cholesterol (HDL-C) among boys (≥3 vs. 0: adjusted-RoGM = 1.08, 1.01-1.17). Sibship characteristics were not associated with lipids among girls.

CONCLUSIONS

Increased number of total, older, and younger siblings were associated with favorable lipid profiles among adolescent boys, but not girls. Mechanisms underlying these associations need further investigations.

Influence of Maternal Active and Secondhand Smoking during Pregnancy on Childhood Obesity at 3 Years of Age: A Nested Case-Control Study from the Japan Environment and Children's Study (JECS)

Maternal smoking during pregnancy is a risk factor for childhood obesity; however, the combined effect of secondhand smoking during pregnancy on children in the early years is unclear. We examined the effects of maternal active and secondhand smoking during pregnancy on childhood obesity in a large population-based cohort. A nested case–control study originating from the Japan Environment and Children’s Study was performed. The maternal smoking status was collected via self-administered questionnaires during mid/late pregnancy. Obesity in children was determined based on BMI measured at 3 years of age. In total, 4875 cases and 19,491 controls were included in the analyses. Conditional logistic regression models with a significance level of 5% (two-tailed test) were used to test the association. The proportion of mothers who continued smoking and who were exposed to secondhand smoking daily during pregnancy were 3.9% and 13.0% in cases and 2.9% and 10.8% in controls, respectively. Continuous maternal smoking was associated with increased odds of obesity compared to those who never smoked or quit smoking before the pregnancy (adjusted odds ratio, 1.39; 95% confidence interval, 1.01–1.92). The odds increased further when combined with secondhand smoking. The promotion of non-smoking among family members, in public and workplace could benefit pregnant women and offspring.

Linkage Between 2 Information Systems: Combined Live Births and Food and Nutrition Surveillance as a Public Health Tool for Investigation of the Determinants of Obesity Among Children and Adolescents in Southern Brazil

BACKGROUND

Childhood obesity has been growing steadily, at an earlier age, and currently comprises a public health issue. A number of studies have pointed to perinatal factors as possible determinants in the development of childhood obesity.

OBJECTIVE

To evaluate the influence of perinatal factors on the development of obesity in children and adolescents in southern Brazil.

DESIGN

Retrospective cohort study in which a linkage was made between anthropometric data of children and adolescents aged 0 to 15 years who had been registered in the Food and Nutrition Surveillance System (SISVAN) from 2008 to 2016 and their perinatal data registered in the Live Birth Information System (SINASC) from 2000 to 2014. The SINASC was used to extract maternal covariables (age, schooling, marital status), prenatal variables (parity and number of prenatal visits), and perinatal variables (type of delivery, sex, and birth weight). Variables such as age, inclusion in the Bolsa Família income transfer program, and the number of anthropometric evaluations were extracted from SISVAN.

RESULTS

The sample comprised 537 children and adolescents. The median age was 8 years (interquartile range: 2-11 years). The prevalence of obesity was 15.1%. Poisson regression revealed a higher risk of obesity in children born via cesarean delivery (relative risk [RR] = 1.48; 95% CI: 1.01-2.17), children of primiparous mothers (RR = 1.72; 95% CI: 1.16-2.53), girls (RR = 1.77; 95% CI:1.21-2.60), and those aged between 5 and 9 years (RR = 26.8; 95% CI: 3.75-191.55) and older than 10 years (RR = 20.74; 95% CI: 2.89-148.61).

CONCLUSIONS

The linkage between SINASC and SISVAN allowed identification of prenatal and perinatal risk factors for the development of childhood obesity. These findings should contribute to the development of health promotion and prevention policies.

Childhood growth of term singletons born after frozen compared with fresh embryo transfer

RESEARCH QUESTION

Is the growth of term singletons born after frozen embryo transfer (FET) comparable to those born after fresh embryo transfer and natural conception up to 5 years of age?

DESIGN

Observational cohort study in an academic medical centre and municipal child health clinics with repeated measurements carried out by medical professionals. Term singletons born after FET (n = 110) and fresh embryo transfer (n = 181) and their matched natural conception controls (n = 543) born in Oulu, Northern Finland, were included. Mean weights, lengths, heights and head circumferences at the ages of 4, 8 and 18 months and 3 and 5 years were compared. At 3 and 5 years, body mass indices were compared.

RESULTS

Childhood growth did not differ between term singletons born after FET, fresh embryo transfer and natural conception, correcting for exact age at measurement and adjusting for maternal body mass index and paternal height.

CONCLUSIONS

Similar growth between children born after FET, fresh embryo transfer and natural conception offers reassurance of the safety and feasibility of the steadily increasing use of embryo cryopreservation in assisted reproduction.

Inequity in health care utilization for common childhood illnesses in India: measurement and decomposition analysis using the India demographic and health survey 2015-16

BACKGROUND

Though child mortality has dropped remarkably, it is considerably high in South Asia. Across the globe, 5.2 million children under 5 years of age died in 2019, and India accounts for a significant portion of these deaths. Common childhood illnesses are the leading cause of these deaths. Seeking care from formal providers can reduce these avoidable deaths. Inequity is a crucial blockage in optimum utilization of medical treatment for children. Hence, the present study analyzes the inequalities and horizontal inequities in utilizing the medical treatment for diarrhea, fever, acute respiratory infection (ARI), and any of these common childhood illnesses in India and across the Indian states. The study also attempts to locate significant contributors to these inequalities.

METHODS

The study used 0 to 59 months children's data sourced from the Demographic and Health Survey, India (2015-16). Concentration Index (CI) and Erreygers Corrected Concentration Index (EI) were used to measure the inequalities. The Horizontal Inequity Index (HII) was deployed to estimate inequity. The decomposition method introduced by Erreygers was applied to determine the significant contributors of inequalities.

RESULTS

The EI in medical treatment-seeking for common childhood illnesses was 0.16, while the HII was 0.15. The highest inequality was perceived in the utilization of medical treatment for ARI (0.17). The primary contributing factors of these inequalities were continuum of maternal care (18.7%), media exposure (12%), affordability (9.3%), place of residence (9.1%), mother's education (8.5%), and state groups (8.8%). The North-Eastern states showed the highest level of inequality across the Indian states.

CONCLUSION

The study reveals that the horizontal inequity in medical treatment utilization for children in India is pro-rich. The findings of the study suggest that attuning the efforts of existing maternal and child health programs into one seamless chain of care can bring the inequalities down and improve the utilization of child health care services. The spread of health education through different media sources, reaching out to rural and remote places with adequate health personnel, and easing out the financial hardship in accessing medical treatment could be the cornerstone in accelerating the utilization level amongst the impoverished children.

Birth order, parental health investment, and health in childhood

We analyze the relationship between birth order, parental health investment and children's health using administrative data from Austria. We show that later-born children have better health endowments at birth. They are less likely born preterm or with a low birth weight, and less likely hospitalized for perinatal conditions. We also find significant birth order differences in parental health investment in early childhood. Later-born children are less likely to participate in preventive medical screenings and their vaccine uptake rates are lower. Our analysis indicates that these birth order differences in parental health investments are not driven by children's health endowments. Thus, we do not find evidence for compensatory behavior of parents. We discuss alternative explanations, such as the role of resource constraints. Furthermore, we show, that the initial health inequalities extend into middle childhood. Later-born children show a better health status in school health checks, they consume less medication and are less often hospitalized.

Birth order is associated with an increased risk of obesity in young adults in Thailand

BACKGROUND

There is a growing body of evidence showing that early life events are associated with increased risk of cardiovascular and metabolic diseases later in adult life. However, there is a paucity of data in this field from Asian populations. In this study, we examined the association of birth order with obesity risk and cardiometabolic outcomes in young adults in Thailand.

METHODS

Participants were the offspring from a birth cohort study in Chiang Mai (northern Thailand), who were followed up at ~20.5 years of age. Clinical assessments included anthropometry, blood pressure, fasting blood samples and carotid intima-media thickness. Insulin sensitivity was estimated using homeostatic model assessment of insulin resistance (HOMA-IR). Participants were stratified into two groups: first-borns and later-borns. Health outcomes between groups were compared using multivariable models adjusting for important confounders, in particular maternal body mass index (BMI).

RESULTS

A total of 559 participants were studied: 316 first-borns (46% males) and 243 later-borns (47% males). Adjusted models showed anthropometric differences, with first-borns being 2.3 kg heavier (p=0.023) with a BMI 0.86 kg/m² greater (p=0.019) than later-borns. Thus, rates of obesity were higher in first-borns than in later-borns (6.6% vs 2.9%), so that first-borns had an adjusted relative risk of obesity 3.3 times greater than later-borns [95% CI 1.42 to 7.88; p=0.006]. There were no observed differences in cardiovascular or metabolic parameters assessed, including HOMA-IR.

CONCLUSION

As observed in other populations, first-borns in Thailand had greater BMI and an increased risk of obesity in young adulthood. However, we observed no other cardiometabolic differences between first- and later-borns.

Association of number of siblings, birth order, and thinness in 3- to 12-year-old children: a population-based cross-sectional study in Shanghai, China

Background

Sibship size and structure have a significant association with overweight and obesity in children, but the relationship with thinness has not been fully studied and understood, especially in Asia. This study evaluated the associations among number of siblings, birth order, and childhood thinness and investigated the association of number of younger or older siblings with childhood thinness.

Methods

In this study, we performed a population-based cross-sectional study among 84,075 3- to 12-year-old children in Shanghai using multistage stratified cluster random sampling. We defined grades 1, 2, and 3 thinness according to the body mass index cutoff points set by the International Obesity Task Force and used multinomial logistic regression models to estimate the odds ratio (OR) and 95% confidence interval (95% CI).

Results

Compared with only children, for boys, children with two or more siblings were more likely to suffer from grade 2 (OR = 1.29, 95% CI 1.02, 1.64) and grade 3 thinness (OR = 1.60, 95% CI 1.07, 2.40); and the youngest child faced a higher risk of grade 2 (OR = 1.44, 95% CI 1.09, 1.90) and grade 3 thinness (OR = 1.53, 95% CI 1.01, 2.33). For girls, children with one sibling were more likely to suffer from grade 1 thinness (OR = 1.22, 95% CI 1.05, 1.42); the oldest child, middle child, and youngest child faced a higher risk of grade 1 (OR = 1.42, 95% CI 1.09, 1.84), grade 2 (OR = 1.26, 95% CI 1.03, 1.54), and grade 1 thinness (OR = 1.87, 95% CI 1.21, 2.88) respectively. There was no statistically significant relationship, however, between a larger number of younger or older siblings and childhood thinness.

Conclusions

Regardless of sex, having either siblings or a higher birth order was positively associated with childhood thinness. The present study has suggested that future interventions to prevent childhood thinness should consider family background as an important factor, especially in multi-child-families.

[Family functioning, parental rearing and its relationship to nutritional status in preschoolers]

Objetivo

Analizar la asociación entre funcionalidad familiar, crianza parental y estado nutricional en preescolares.

Diseño

Estudio cuantitativo, descriptivo correlacional y transversal.

Emplazamiento

Instituciones públicas de educación preescolar en el estado de Nuevo León, México. Atención Primaria.

Participantes

Muestra compuesta por 228 diadas (madre o padre y preescolar); se tomó como único criterio de inclusión ser el responsable principal de la crianza del preescolar.

Mediciones principales

Se empleó un cuaderno de recogida datos sociodemográficos, el estado nutricional se determinó basándose en recomendaciones de la Organización Mundial de la Salud, se utilizaron la Escala de Evaluación de la Cohesión y la Adaptabilidad Familiar y el cuestionario de Estilos de Crianza Parental. Se obtuvo estadística descriptiva y el coeficiente de correlación de Spearman.

Resultados

El promedio de edad de los padres fue de 32,09 años, el 60,5% de las madres se dedican al hogar y el 100% de los padres trabaja; la media de escolaridad en años fue de 12,16; el 68,9% de los participantes son casados; referente a los preescolares, el 29,4% presentó sobrepeso u obesidad. En cuanto a la funcionalidad familiar, se identificó que en la dimensión de cohesión es semirrelacionada el 44,3%. El estilo de crianza parental que predominó en los padres fue el permisivo con el 62,3%.

Conclusiones

La mayoría de los padres de familia presentaron desequilibrio en la funcionalidad familiar. No se encontró significación estadística entre funcionalidad familiar y crianza parental con estado nutricional en preescolares (p < 0,05).

Campylobacter infection and household factors are associated with childhood growth in urban Bangladesh: An analysis of the MAL-ED study

The dual burden of enteric infection and childhood malnutrition continues to be a global health concern and a leading cause of morbidity and death among children. Campylobacter infection, in particular, is highly prevalent in low- and middle-income countries, including Bangladesh. We examined longitudinal data to evaluate the trajectories of change in child growth, and to identify associations with Campylobacter infection and household factors. The study analyzed data from 265 children participating in the MAL-ED Study in Mirpur, Bangladesh. We applied latent growth curve modelling to evaluate the trajectories of change in children's height, as measured by length-for-age z-score (LAZ), from age 0-24 months. Asymptomatic and symptomatic Campylobacter infections were included as 3- and 6-month lagged time-varying covariates, while household risk factors were included as time-invariant covariates. Maternal height and birth order were positively associated with LAZ at birth. An inverse association was found between increasing age and LAZ. Campylobacter infection prevalence increased with age, with over 70% of children 18-24 months of age testing positive for infection. In the final model, Campylobacter infection in the preceding 3-month interval was negatively associated with LAZ at 12, 15, and 18 months of age; similarly, infection in the preceding 6-month interval was negatively associated with LAZ at 15, 18, and 21 months of age. Duration of antibiotic use and access to treated drinking water were negatively associated with Campylobacter infection, with the strength of the latter effect increasing with children's age. Campylobacter infection had a significant negative effect on child's growth and this effect was most powerful between 12 and 21 months. The treatment of drinking water and increased antibiotic use have a positive indirect effect on linear child growth trajectory, acting via their association with Campylobacter infection.

Developmental plasticity as adaptation: adjusting to the external environment under the imprint of maternal capital

Plasticity is assumed to enable beneficial adjustment to the environment. In this context, developmental plasticity is generally approached within a two-stage framework, whereby adjustments to ecological cues in stage 1 are exposed to selection in stage 2. This conceptual approach may have limitations, because in species providing parental investment, particularly placental mammals such as humans, initial adjustments are not to the environment directly, but rather to the niche generated by parental phenotype (in mammals, primarily that of the mother). Only as maternal investment is withdrawn is the developing organism exposed directly to prevailing ecological conditions. A three-stage model may therefore be preferable, where developmental trajectory first adjusts to maternal investment, then to the external environment. Each offspring experiences a trade-off, benefitting from maternal investment during the most vulnerable stages of development, at the cost of exposure to investment strategies that maximize maternal fitness. Maternal life-history trade-offs impact the magnitude and schedule of her investment in her offspring, generating lifelong effects on traits related to health outcomes. Understanding the imprint of maternal capital on offspring is particularly important in species demonstrating social hierarchy. Interventions targeting maternal capital might offer new opportunities to improve health outcomes of both mother and offspring. This article is part of the theme issue 'Developing differences: early-life effects and evolutionary medicine'.

Associations of fat mass and fat-free mass accretion in infancy with body composition and cardiometabolic risk markers at 5 years: The Ethiopian iABC birth cohort study

BACKGROUND

Accelerated growth in early childhood is an established risk factor for later obesity and cardiometabolic disease, but the relative importance of fat mass (FM) and fat-free mass (FFM) accretion is not well understood. We aimed to study how FM and FFM at birth and their accretion during infancy were associated with body composition and cardiometabolic risk markers at 5 years.

METHODS AND FINDINGS

Healthy children born at term were enrolled in the Infant Anthropometry and Body Composition (iABC) birth cohort between December 2008 and October 2012 at Jimma University Specialized Hospital in the city of Jimma, Ethiopia. FM and FFM were assessed using air displacement plethysmography a median of 6 times between birth and 6 months of age. In 507 children, we estimated individual FM and FFM at birth and their accretion over 0-3 and 3-6 months of age using linear-spline mixed-effects modelling. We analysed associations of FM and FFM at birth and their accretion in infancy with height, waist circumference, FM, FFM, and cardiometabolic risk markers at 5 years using multiple linear regression analysis. A total of 340 children were studied at the 5-year follow-up (mean age: 60.0 months; girls: 50.3%; mean wealth index: 45.5 out of 100; breastfeeding status at 4.5 to 6 months post-partum: 12.5% exclusive, 21.4% almost exclusive, 60.6% predominant, 5.5% partial/none). Higher FM accretion in infancy was associated with higher FM and waist circumference at 5 years. For instance, 100-g/month higher FM accretion in the periods 0-3 and 3-6 months was associated with 339 g (95% CI: 243-435 g, p < 0.001) and 367 g (95% CI: 250-484 g, p < 0.001) greater FM at 5 years, respectively. Higher FM at birth and FM accretion from 0 to 3 months were associated with higher FFM and cholesterol concentrations at 5 years. Associations for cholesterol were strongest for low-density lipoprotein (LDL)-cholesterol, and remained significant after adjusting for current FM. A 100-g higher FM at birth and 100-g/month higher FM accretion from 0 to 3 months were associated with 0.16 mmol/l (95% CI: 0.05-0.26 mmol/l, p = 0.005) and 0.06 mmol/l (95% CI: 0.01-0.12 mmol/l, p = 0.016) higher LDL-cholesterol at 5 years, respectively. Higher FFM at birth and FFM accretion in infancy were associated with higher FM, FFM, waist circumference, and height at 5 years. For instance, 100-g/month higher FFM accretion in the periods 0-3 and 3-6 months was associated with 1,002 g (95% CI: 815-1,189 g, p < 0.001) and 624 g (95% CI: 419-829 g, p < 0.001) greater FFM at 5 years, respectively. We found no associations of FM and FFM growth with any of the other studied cardiometabolic markers including glucose, HbA1c, insulin, C-peptide, HOMA-IR, triglycerides, and blood pressure. Non-attendance at the 5-year follow-up visit was the main limitation of this study, which may have introduced selection bias and limited the power of the regression analyses.

CONCLUSIONS

FM accretion in early life was positively associated with markers of adiposity and lipid metabolism, but not with blood pressure and cardiometabolic markers related to glucose homeostasis. FFM accretion was primarily related to linear growth and FFM at 5 years.

The differences of lipid profiles between only children and children with siblings: A national survey in China

With the increasing number of the one-child family, it is important to investigate whether the only-child status is associated with dyslipidemia. Among a national sample of 65,347 Chinese children aged 6–17 years, 16,100 lipid profiles were available. Children’s height, weight, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured. In comparison to children with siblings, only children (OC) were more likely to be boys and live in urban areas. OC had less physical activity, less fried food intake, but more meat and dairy intakes. OC had significantly higher levels of TC (3.97 ± 0.78 vs. 3.89 ± 0.77) and LDL-C (2.12 ± 0.65 vs. 2.06 ± 0.64) in the overall group, and also in the subgroups of rural boys and girls. The prevalence of hyper-TC (5.48% vs. 4.43%) and hyper-LDL-C (3.97% vs. 2.96%) were significantly higher in OC than their counterparts. Furthermore, we found higher odds of hyper-LDL-C [1.43 (1.12, 1.83)] in OC after adjustments. In the subgroup analysis, only-child status was associated with increased risk of hyper-TC [1.86 (1.06, 3.26)] and hyper-LDL-C [2.65 (1.14, 6.16)] among rural boys, and hyper-LDL-C among rural girls [2.20 (1.14, 4.22)]. In conclusion, higher levels of TC and LDL-C were found in OC especially for rural children. Being an only-child was associated with increased risk of hyper-LDL-C.

Correlates of elevated blood pressure in healthy children: a systematic review

The prevalence of hypertension in children is increasing globally. Addressing this will require a robust understanding of associated risk factors. To this end, we conducted a systematic review to identify correlates of elevated blood pressure (BP) in children. Literature searches were conducted using pre-defined search terms from three academic databases. The abstract and full text of identified studies were screened for eligibility by two independent reviewers. A total of 100 studies were included in this systematic review. An assessment tool was first used to assess study quality; a narrative synthesis was then performed. We found a broad range of physiological, social and behavioural factors associated with elevated BP in children. The most common correlate observed was adiposity, suggesting that childhood obesity may be implicated in the increased prevalence of hypertension observed in children. However, the broad range of other factors identified underscores the multi-factorial aetiology of hypertension. Data from a broad range of studies showed that the correlates of hypertension in children are multi-factorial. Therefore, approaches aimed at preventing hypertension must in turn be multi-factorial to ensure that the burden of hypertension in childhood is addressed.

Body composition during early infancy and its relation with body composition at 4 years of age in Jimma, an Ethiopian prospective cohort study

BACKGROUND/OBJECTIVES

Low and high birth weight and rapid weight gain during infancy are associated with childhood obesity. Associations of birth and infancy body composition (BC) growth with childhood BC remain unknown in low-income countries. We aimed to investigate the associations of fat mass (FM) and fat-free mass (FFM) at birth and its accretion during early infancy with FM and FFM at the age of 4 years.

METHODS

In the infant Anthropometry and Body Composition (iABC) cohort, BC was assessed at six consecutive time points from birth to 6 months and at 4 years of age by air displacement plethysmography. Multiple linear regression models were used to determine the association between FM and FFM at birth and their accretion rates during infancy and FM index (FMI) and FFM index (FFMI) at 4 years in 314 children.

RESULTS

One kilogram higher FFM at birth was associated with a 1.07 kg/m2 higher FFMI (95% CI 0.60, 1.55) at 4 years while a one SD increment in FFM accretion rate from 0 to 6 months was associated with a 0.24 kg/m2 increment in FFMI (95% CI 0.11, 0.36) and with a 0.20 kg/m2 higher FMI at 4 years (β = 0.20; 95% CI 0.04, 0.37). FFM at birth did not predict FMI at 4 years. FM at birth was associated with 1.17 kg/m2 higher FMI at 4 years (95% CI 0.13, 2.22) whereas FM accretion from 0 to 4 months was associated with an increase in FMI of 0.30 kg/m2 (95% CI 0.12, 0.47). FM at birth did not predict FFMI at 4 years, and neither did FM accretion from 0 to 4 months.

CONCLUSIONS

A higher FFM in early infancy predicted higher FFMI at 4 years while a higher FM accretion during early infancy predicted higher FMI at 4 years. Follow-up studies are merited to explore associations of childhood BC with cardio-metabolic risk later in life.

Associations of stunting at 2 years with body composition and blood pressure at 8 years of age: longitudinal cohort analysis from lowland Nepal

BACKGROUND

Stunting remains a very common form of child malnutrition worldwide, particularly in South Asian populations. There is poor understanding of how it develops and how it is associated with subsequent phenotype.

SUBJECTS/METHODS

We used data from a longitudinal cohort of children (n = 841) in lowland Nepal to investigate associations of stunting at 2 years with maternal traits and early growth patterns, and with body size and composition, kidney dimensions by ultrasound, lung function by spirometry and blood pressure (BP) at 8 years.

RESULTS

Compared to non-stunted children, children stunted at 2 years came from poorer families and had shorter, lighter mothers. They tended to have higher birth order, were born smaller, and remained shorter, lighter and thinner at 8 years. They had lower leg length, lean and fat masses, smaller kidneys, and reduced lung function (all p < 0.0001). These differences persisted with smaller magnitude after adjusting for current height, maternal height and education, family assets and birth order. Stunting was not associated with BP.

DISCUSSION

Stunting developed on an inter-generational timescale in this population and its risk increased with birth order. At 8 years, children stunted at 2 years had deficits in tissue masses and some aspects of physical function that were only partially attributable to their persisting short height and maternal phenotype. This suggests that the early stunting is associated with greater deficits in long-term outcomes than would be expected from the persistent short stature alone.

Adjustment for time-invariant and time-varying confounders in 'unexplained residuals' models for longitudinal data within a causal framework and associated challenges

‘Unexplained residuals’ models have been used within lifecourse epidemiology to model an exposure measured longitudinally at several time points in relation to a distal outcome. It has been claimed that these models have several advantages, including: the ability to estimate multiple total causal effects in a single model, and additional insight into the effect on the outcome of greater-than-expected increases in the exposure compared to traditional regression methods. We evaluate these properties and prove mathematically how adjustment for confounding variables must be made within this modelling framework. Importantly, we explicitly place unexplained residual models in a causal framework using directed acyclic graphs. This allows for theoretical justification of appropriate confounder adjustment and provides a framework for extending our results to more complex scenarios than those examined in this paper. We also discuss several interpretational issues relating to unexplained residual models within a causal framework. We argue that unexplained residual models offer no additional insights compared to traditional regression methods, and, in fact, are more challenging to implement; moreover, they artificially reduce estimated standard errors. Consequently, we conclude that unexplained residual models, if used, must be implemented with great care.

Does planning of births affect childhood undernutrition? Evidence from demographic and health surveys of selected South Asian countries

OBJECTIVE

The prevalence of child undernutrition in South Asia is high, as is also the unmet need for family planning. In previous literature, the biodemographic relationship of family planning, particularly birth order and birth spacing, and nutritional status of children have been assessed separately. The aim of this study was to work on the hypothesis that the planning of births comprising timing, spacing, and number of births improves child undernutrition, especially in the areas with high prevalence of stunting and underweight.

METHODS

We used recent Demographic and Health Survey data from four selected South Asian countries. Binary logistic regression models were applied to estimate the adjusted percentage of stunting and underweight by identified independent factors.

RESULTS

Findings suggested that after controlling for other socioeconomic factors, children in the first birth order with >24 mo of interval between marriage and first birth have a lower risk for stunting (20%; p <0.01) and underweight (14%; p <0.05), respectively, than other scenarios of the planning of births. The probability of child undernutrition is lower among children born with >24 mo of birth spacing than its counterpart in all birth orders, but the significance of birth spacing reduces with increasing birth orders.

CONCLUSION

Appropriate planning of births using family planning methods in countries with high birth rates has the potential to reduce childhood undernutrition. Thus, the planning of births emerges as an important biodemographic approach to eradicate childhood undernutrition especially in developing regions like South Asia and thereby to achieve sustainable development goals by 2030.

Who is more likely to be obese or overweight among siblings? A nationally representative study in rural China

Background

The aims of this study were to determine the association between sibling rank and childhood obesity among children ≤ 5 years of age in rural China, and to investigate the effect of child gender and the obesity status of other siblings on this association.

Methods

Data from the China Family Panel Studies, a nationally representative survey, was used for the analysis. Sibling rank was defined as the birth order of all children with the same biological mother. A total of 1116 children ≤ 5 years of age were divided into four groups: children without siblings, first-born children, second-born children, and third-born or younger children. For each child, the body mass index and standard deviation (BMI z score) was calculated according to WHO standards; children with BMI z scores > 2 were classified as obese or overweight (ObOw). Logistic regression models were used to estimate the association between sibling rank and ObOw status, and the possible influence of gender and ObOw status among other siblings.

Results

The second and third-born or younger children had a significantly higher risk of becoming ObOw than children without siblings (odds ratio [OR]: 1.32, 95% confidence interval [CI]: 1.07–1.63 and OR:1.38, 95% CI: 1.17–1.63, respectively). Specifically, female second-born children and male third-born or younger children had a significantly higher risk of ObOw (OR: 1.50, 95% CI: 1.11–2.01 and OR: 1.57, 95% CI: 1.07–2.32, respectively). Having an ObOw sibling increased the probability of being ObOw and the magnitude of the effect was larger if siblings were younger.

Conclusions

Sibling rank was shown to be associated with ObOw status among children 0–5 years of age in rural China. Our findings can help healthcare practitioners and authorities to identify children at risk of obesity. Future studies should focus on the mechanisms of this association.

Malnutrition and birth related determinants among children in Qazvin, Iran

Background

Little is known about the effect of birth weight, birth order and number of siblings on the nutritional status in children in Iran, especially in Qazvin province. The aim of this study was to provide the current data on malnutrition and birth related determinants among children in Qazvin, Iran. This study was conducted in six cities of Qazvin province (Iran), during December 2009-December 2010. Data on age, weight and height were taken and birth weight, number of children in family, birth order, parental career and educational state and family caretaker were collected by a questionnaire that a trained team filled in. Sample size was1351, almost 225 children under 6-years-old from each city participated in the study (692 boys and 659 girls). In each city, subjects were randomly selected among children who had profiles at health centers. The overall prevalence of wasting, stunting and underweight was 10.3%, 5.8% and 4.8% respectively. There was association between 'birth weight' and wasting ( P = 0.022), stunting ( P = 0.032) and underweight ( P < 0.001). A non-significant association was obtained between factors 'number of children at home' and 'birth order' with wasting, stunting and underweight. These data suggest that birth weight can influence malnutrition indicators; therefore, knowing risk factors of malnutrition in population subgroups is important for planners in country because it helps the future studies concentrate on the most determining ones.

Healthy(?), wealthy, and wise: Birth order and adult health

While recent research has found that birth order affects outcomes such as education and earnings, the evidence for effects on health is more limited. This paper uses a large Norwegian dataset to focus on the relationship between birth order and a range of health and health-related behaviors, outcomes not previously available in datasets of this magnitude. Interestingly, we find complicated effects of birth order. First-borns are more likely to be overweight, to be obese, and to have high blood pressure and high triglycerides. For example, compared to fifth-borns, first-borns are about 5% points more likely to be obese and 7% points more likely to have high blood pressure. So, unlike education or earnings, there is no clear first-born advantage in health. However, first-borns are about 13% points less likely to smoke daily than fifth-borns and are more likely to report good physical and mental health. Later-borns also score lower on well-being with fifth-borns being about 9% points less likely than first-borns to report that they are happy. Our findings are generally monotonic with middle-borns having outcomes that are intermediate between first- and fifth-borns. We find that these effects are largely unaffected by conditioning on education and earnings, suggesting that these are not the only important pathways to health differentials by birth order. When we explore possible mechanisms, we find that early maternal investment may play a role in birth order effects on health.

Body composition and the monitoring of non-communicable chronic disease risk

There is a need for simple proxies of health status, in order to improve monitoring of chronic disease risk within and between populations, and to assess the efficacy of public health interventions as well as clinical management. This review discusses how, building on recent research findings, body composition outcomes may contribute to this effort. Traditionally, body mass index has been widely used as the primary index of nutritional status in children and adults, but it has several limitations. We propose that combining information on two generic traits, indexing both the ‘metabolic load’ that increases chronic non-communicable disease risk, and the homeostatic ‘metabolic capacity’ that protects against these diseases, offers a new opportunity to improve assessment of disease risk. Importantly, this approach may improve the ability to take into account ethnic variability in chronic disease risk. This approach could be applied using simple measurements readily carried out in the home or community, making it ideal for M-health and E-health monitoring strategies.

The effects of pre-pregnancy BMI and maternal factors on the timing of adiposity rebound in offspring

OBJECTIVE

To assess the effect of pre-pregnancy body mass index (BMI), gestational weight gain (GWG), and other maternal factors on the timing of adiposity rebound (AR).

METHODS

In this study, 594 mothers (mothers who do not have diabetes and not underweight) from the longitudinal Growth and Obesity Chilean Cohort Study self-reported their weights at the beginning and end of their pregnancies, and their heights were measured. Pre-pregnancy BMI was categorized as normal weight, overweight, or obesity, and GWG was assessed according to Institute of Medicine guidelines. For children, weight and height measurements from 0 to 3 years were retrieved from records, and they were measured from age 4 to 7 years. BMI curves from 0 to 7 years were used to estimate the age at AR, which was categorized as early (<5 years), intermediate (5-7 years), or late (>7 years). The associations between pre-pregnancy BMI and GWG and early AR were tested using logistic regression models.

RESULTS

In total, 33% of the mothers had excess pre-pregnancy weight, 31.2% exceeded Institute of Medicine recommendations, and 45% of children had early AR. The pre-pregnancy BMI and parity were associated with earlier AR (OR = 1.07, 95% CI = 1.02-1.11; OR = 0.86; 95% CI = 0.74-0.99, respectively), but GWG was unrelated.

CONCLUSIONS

These results suggest that preventive strategies for promoting normal pre-pregnancy BMI, especially in women's first pregnancies, could delay the timing of AR, with protective metabolic effects on offspring.

Associations of Birth Order with Early Adolescent Growth, Pubertal Onset, Blood Pressure and Size: Evidence from Hong Kong's "Children of 1997" Birth Cohort

Background

Birth order has been proposed as a cardiovascular risk factor, because the lower birth weight and greater infant weight gain typical of firstborns could programme metabolism detrimentally.

Methods

We examined the associations of birth order (firstborn or laterborn) with birth weight-for-gestational age, length/height and body mass index (BMI) z-scores during infancy, childhood, and puberty using generalized estimating equations, with age at pubertal onset using interval-censored regression and with age-, sex- and height-standardized blood pressure, height and BMI z-scores at 13 years using linear regression in a population-representative Chinese birth cohort: “Children of 1997” (n = 8,327).

Results

Compared with laterborns, firstborns had lower birth weight-for-gestational age (mean difference = -0.18 z-score, 95% confidence interval (CI) -0.23, -0.14), lower infant BMI (-0.09 z-score, 95% CI -0.14, -0.04), greater childhood height (0.10 z-score, 95% CI 0.05, 0.14) and BMI (0.08 z-score, 95% CI 0.03, 0.14), but not greater pubertal BMI (0.05 z-score, 95% CI -0.02, 0.11), adjusted for sex, parental age, birthplace, education and income. Firstborns had earlier onset of pubic hair (time ratio = 0.988, 95% CI 0.980, 0.996), but not breast or genitalia, development. Firstborns had greater BMI (0.07 z-score, 95% CI 0.002, 0.15), but not height (0.05 z-score, 95% CI -0.01, 0.11), at 13 years, but similar blood pressure.

Conclusions

Differences by birth order continue into early adolescence with firstborns being heavier with earlier pubic hair development, which could indicate long-term cardiovascular risk.

Association between Birth Interval and Cardiovascular Outcomes at 30 Years of Age: A Prospective Cohort Study from Brazil

Background

Birth interval is an important and potentially modifiable factor that is associated with child health. Whether an association exists with longer-term outcomes in adults is less well known.

Methods

Using the 1982 Pelotas (Brazil) Birth Cohort Study, the association of birth interval with markers of cardiovascular health at 30 years of age was examined. Multivariable linear regression was used with birth interval as a continuous variable and categorical variable, and effect modification by gender was explored.

Results

Birth interval and cardiovascular data were present for 2,239 individuals. With birth interval as a continuous variable, no association was found but stratification by gender tended to show stronger associations for girls. When compared to birth intervals of <18 months, as binary variable, longer intervals were associated with increases in height (1.6 cm; 95% CI: 0.5, 2.8) and lean mass (1.7 kg; 95% CI: 0.2, 3.2). No difference was seen with other cardiovascular outcomes.

Conclusions

An association was generally not found between birth interval and cardiovascular outcomes at 30 years of age, though some evidence existed for differences between males and females and for an association with height and lean mass for birth intervals of 18 months and longer.

Birth order and sibship composition as predictors of overweight or obesity among low-income 4- to 8-year-old children

OBJECTIVE

This study aimed to examine the association of birth order and number and sex of siblings with overweight or obesity among 4- to 8-year-olds.

METHODS

This is a cross-sectional study involving 273 low-income mother-child dyads. Questionnaires and anthropometry were completed. Multiple logistic regression was used to examine the association of birth order, having younger siblings, having older siblings, having at least one brother and having at least one sister with odds of overweight or obesity. Analyses were repeated to additionally include non-biological siblings. Models were adjusted for potential confounders and intermediate variables.

RESULTS

Prevalence of child overweight or obesity was 42.5%. Adjusting for covariates, only children and youngest siblings had higher odds of overweight or obesity compared with oldest siblings (odds ratio [OR]: 4.18, 95% confidence interval [CI]: 1.67, 10.46 and OR: 3.21, 95% CI: 1.41, 7.33, respectively). Having one or more younger siblings and having at least one brother were associated with lower odds (OR: 0.38, 95% CI: 0.21, 0.69 and OR: 0.47, 95% CI: 0.28, 0.81, respectively). Including non-biological siblings did not meaningfully change the associations.

CONCLUSION

Birth order and sibship composition are associated with overweight or obesity among 4- to 8-year-olds. Future studies identifying the underlying behavioural mechanism can help inform family-based intervention programmes.

WHO Child Growth Standards Are Often Incorrectly Applied to Children Born Preterm in Epidemiologic Research

In epidemiologic research, there is no standard approach for accounting for gestational age (GA) at birth when interpreting postnatal anthropometric data in analyses of cohorts that include children born preterm (CBP). A scoping review was conducted to describe analytical approaches to account for GA at birth when applying the WHO Growth Standards (WHO-GS) to anthropometric data in epidemiologic studies. We searched PubMed, Scopus, MEDLINE, Embase, and Web of Science for studies that applied WHO-GS, included CBP in the study population, had access to data within 1 mo of age, and were published between 2006 and 2015 in English. Of the 80 included studies that used the WHO-GS, 80% (64 of 80) included all children regardless of GA, whereas 20% (16 of 80) restricted analyses that used WHO-GS to term-born children. Among the 64 studies that included all children, 53 (83%) used chronological age and 11 (17%) used corrected age for CBP. Of the 53 studies that used chronological age, 12 (23%) excluded data that were likely contributed by CBP (e.g., very low birth weight or extremely low outlying z scores) and 19 (36%) adjusted for or stratified by GA at birth in regression analyses. In summary, researchers commonly apply WHO-GS to CBP, usually based on chronological age. Methodologic challenges of analyzing data from CBP in the application of WHO-GS were rarely explicitly addressed. Further efforts are required to establish acceptable approaches to account for heterogeneity in GA at birth in the analysis of post-term anthropometric data in epidemiologic research.

First-borns have greater BMI and are more likely to be overweight or obese: a study of sibling pairs among 26,812 Swedish women

BACKGROUND

A number of large studies have shown phenotypic differences between first-borns and later-borns among adult men. In this study, we aimed to assess whether birth order was associated with height and BMI in a large cohort of Swedish women.

METHODS

Information was obtained from antenatal clinic records from the Swedish National Birth Register over 20 years (1991-2009). Maternal anthropometric data early in pregnancy (at approximately 10-12 weeks of gestation) were analysed on 13,406 pairs of sisters who were either first-born or second-born (n=26,812).

RESULTS

Early in pregnancy, first-born women were of BMI that was 0.57 kg/m(2) (2.4%) greater than their second-born sisters (p<0.0001). In addition, first-borns had greater odds of being overweight (OR 1.29; p<0.0001) or obese (OR 1.40; p<0.0001) than second-borns. First-borns were also negligibly taller (+1.2 mm) than their second-born sisters. Of note, there was a considerable increase in BMI over the 18-year period covered by this study, with an increment of 0.11 kg/m(2) per year (p<0.0001).

CONCLUSIONS

Our study corroborates other large studies on men, and the steady reduction in family size may contribute to the observed increase in adult BMI worldwide.

FACTORS ASSOCIATED WITH CHILDREN'S HEIGHT AND BODY MASS INDEX IN LITHUANIA, 1990-2008

The aim of the study was to reveal the ethnic and socioeconomic factors associated with height and body mass index (BMI) of children during the period of political and social transition in Lithuania in 1990-2008. Data were derived from the personal health records of 1491 children (762 boys and 729 girls) born in 1990 in Vilnius city and region. Height and BMI from birth up to the age of 18 years were investigated. Children were divided into groups according to their ethnicity, place of residence, father's and mother's occupation and birth order. Height and BMI were compared between the groups; a Bonferroni correction was applied. A multiple linear regression model was used to measure the effects of the independent variables on height and BMI. Girls living in Vilnius city were significantly taller in later life at the ages of 8 and 11 years. Sons of mothers employed as office workers appeared to be significantly taller at the ages of 7, 12, 14 and 15 years compared with the sons of labourers. First-born girls were taller at the age of 7 years than later-born girls of the same age (124.48±5.11 cm and 122.92±5.14 cm, respectively, p<0.001). Later-born children of both sexes had higher BMIs at birth compared with first-borns; however, first-born girls had higher BMIs at the age of 11 years compared with their later-born peers (17.78±2.87 kg/m² and 16.79±2.14 kg/m² respectively, p<0.001). In the multiple linear regression model, the five tested independent variables explained only up to 18% of total variability. Boys were more sensitive to ethnic and socioeconomic factors: ethnicity appeared to be a significant predictor of boys' height at the age of 5 years (p<0.001), while birth order (p<0.001) predicted boys' BMI at birth. In general, ethnicity, place of residence, father's and mother's occupation and birth order were not associated with children's height and BMI in most age groups.

The influence of birth order and number of siblings on adolescent body composition: evidence from a Brazilian birth cohort study

The aim of this study was to estimate the association between birth order and number of siblings with body composition in adolescents. Data are from a birth cohort study conducted in Pelotas, Brazil. At the age of 18 years, 4563 adolescents were located, of whom 4106 were interviewed (follow-up rate 81·3 %). Of these, 3974 had complete data and were thus included in our analysis. The variables used in the analysis were measured during the perinatal period, or at 11, 15 and/or 18 years of age. Body composition at 18 years was collected by air displacement plethysmography (BOD POD^®). Crude and adjusted analyses of the association between birth order and number of siblings with body composition were performed using linear regression. All analyses were stratified by the adolescent sex. The means of BMI, fat mass index and fat-free mass index among adolescents were 23·4 (sd 4·5) kg/m², 6·1 (sd 3·9) kg/m² and 17·3 (sd 2·5) kg/m², respectively. In adjusted models, the total siblings remained inversely associated with fat mass index (β = − 0·37 z-scores, 95 % CI − 0·52, − 0·23) and BMI in boys (β = − 0·39 z-scores, 95 % CI − 0·55, − 0·22). Fat-free mass index was related to the total siblings in girls (β = 0·06 z-scores, 95 % CI − 0·04, 0·17). This research has found that number of total siblings, and not birth order, is related to the fat mass index, fat-free mass index and BMI in adolescents. It suggests the need for early prevention of obesity or fat mass accumulation in only children.

Low birthweight and postnatal weight in full-term infants under six months old, Rio de Janeiro, RJ, Brazil

This study investigated the association between low birthweight and postnatal weight in full-term infants, taking social, economic, maternal and babies characteristics into account. A cross-sectional study was conducted with infants under six months old at 27 primary healthcare units in the Rio de Janeiro municipality, Brazil, in 2007. Only singleton full-term babies were included. The association between full-term low birthweight and postnatal weight was tested using the multiple regression model adjusted for the gender and age of the baby, as well as potential confounding factors. A total of 875 babies were evaluated, of whom 4.5% were small for gestational age. Small-for-gestational-age babies weighted, on average, 977.4 grams less than those born with adequate weight for gestational age, after adjustment by gender and age, as well as marital status and parity. Girls were 426.74 grams lighter than boys; children from mothers with live-in partners were 146.2 grams heavier than those of single mothers, and the babies of primiparae weighed 204.67 grams less than the children of multiparae. Low birthweight is an unfavorable factor for postnatal weight of full-term infants. These children, particularly daughters of primipara single mothers, must be followed more frequently in relation to their postnatal growth.

Assessment of nutritional status among adolescent boys in an urban population of South India

BACKGROUND

Deficiency of calories and certain micronutrients is known to cause growth faltering in children and adolescents. It is recognized that varieties of foods need to be consumed in order to meet requirements for essential nutrients. Lack of diversity in the diets is a serious problem among poor populations in the developing world. The extent of variations in intake of nutrients occurring in a homogeneous population provides useful information.

SUBJECTS & METHODS

This study investigates the mean intake of nutrient by 1083 adolescent males, age 10-19 years, in comparison to the RDA values suggested by ICMR for Indians. Food intakes, social class and knowledge about health education were obtained by questionnaires. Descriptive statistics, non-parametric statistics, and Chi-Square tests were performed to and interpret the data, particularly hypothesis testing.

RESULTS

Mean intake of calories varied from 1512 ± 532 for pre-adolescent to 1742 ± 660 for post-adolescence, the differences in intake between pre-adolescence to adolescence was statistically significant. The intake was largely different compared to the respective RDAs including proteins which were markedly lower than the RDA. The mean intake increased linearly with the advancing stages of adolescence. Intake of calcium by boys during pre-adolescence and adolescence stage were lower by 20-30% as compared to the RDA, whereas the post-adolescent boys were found to consume a fair amount and met their RDAs. Intakes of iron and ?-carotene were highly variable, the majority of the selected boys consumed much less than the RDAs. The differences in the intakes were statistically not significant.

CONCLUSION

Mean intakes of nutrients indicate that the majority of the selected boys consumed protein, calories, iron, calcium and ? carotene in three stages of adolescent markedly lower than the respective RDAs. Family type, birth order and SES correlated with nutrient intake among selected adolescent boys.

Maternal parity, fetal and childhood growth, and cardiometabolic risk factors

We examined the associations of maternal parity with fetal and childhood growth characteristics and childhood cardiometabolic risk factors in a population-based prospective cohort study among 9031 mothers and their children. Fetal and childhood growth were repeatedly measured. We measured childhood anthropometrics, body fat distribution, left ventricular mass, blood pressure, blood lipids, and insulin levels at the age of 6 years. Compared with nulliparous mothers, multiparous mothers had children with higher third trimester fetal head circumference, length and weight growth, and lower risks of preterm birth and small-size-for-gestational-age at birth but a higher risk of large-size-for-gestational-age at birth (P<0.05). Children from multiparous mothers had lower rates of accelerated infant growth and lower levels of childhood body mass index, total fat mass percentage, and total and low-density lipoprotein cholesterol than children of nulliparous mothers (P<0.05). They also had a lower risk of childhood overweight (odds ratio, 0.75 [95% confidence interval, 0.63–0.88]). The risk of childhood clustering of cardiometabolic risk factors was not statistically significantly different (odds ratio, 0.82; 95% confidence interval, 0.64–1.05). Among children from multiparous mothers only, we observed consistent trends toward a lower risk of childhood overweight and lower cholesterol levels with increasing parity (P<0.05). In conclusion, offspring from nulliparous mothers have lower fetal but higher infant growth rates and higher risks of childhood overweight and adverse metabolic profile. Maternal nulliparity may have persistent cardiometabolic consequences for the offspring.

Association of characteristics of delivery and medical conditions during the first month of life with developmental defects of enamel

Background

Developmental defects of enamel (DDE) may be influenced by health problems and illness in children. The aim of the study was to identify the main characteristics of birth (delivery) and adverse medical conditions during the first month of life that may be related to DDE in permanent teeth.

Methods

1000 schoolchildren between the ages of 9 and 11 years were selected for this cross-sectional study by multistage randomization from four educational zones in Shiraz in 2013. Intraoral examination was used to diagnose DDE according to World Health Organization screening guidelines and the Modified DDE Index. The data on seven birth factors as well as health and nutritional conditions during the first month of life were collected by a questionnaire completed by the parents, and were analyzed with the chi-squared test, Spearman’s correlation and binary logistic regression.

Results

469 (48.2%) out of 974 schoolchildren had at least one permanent tooth with DDE. The defects were significantly related with Apgar score at birth <7 (p = 0.003) and illness during the first month (p = 0.035). The frequency of DDE was significantly lower in the third child in families compared to the first and second child (p = 0.005). However, DDE showed no significant relationship with gestational age, delivery type, birth weight, gender or type of feeding during early infancy.

Conclusions

Three associated factors were identified (birth Apgar score, illness during the first month of life, birth order) for DDE in permanent teeth. No specific illness was found to be significantly associated with DDE.

Scaling-up access to family planning may improve linear growth and child development in low and middle income countries

BACKGROUND

A large literature has indicated a robust association between birth spacing and child survival, but evidence on the association of birth timing with physical growth in low and middle income countries (LMICs) remains limited.

METHODS AND RESULTS

Data from 153 cross-sectional Demographic and Health Surveys (DHS) across 61 LMICs conducted between 1990 and 2011 were combined to assess the association of birth timing with child stunting (height-for-age z-score <-2). A total of 623,789 children of birth order 1-5 contributed to the maternal age analysis, while the birth spacing dataset consisted of 584,226 children of birth order 2 and higher. Compared to 27-34 year old mothers, maternal age under 18 years was associated with a relative stunting risk of 1.35 (95% CI: 1.29-1.40) for firstborn children, whereas the relative risk was 1.24 (95% CI: 1.19-1.29) for mothers aged 18-19 years. The association of young maternal age with stunting was significantly greater for urban residents and those in the top 50% of household wealth. Birth intervals less than 12 months and 12-23 months had relative risks for stunting of 1.09 (95% CI: 1.06-1.12) and 1.06 (95% CI: 1.05-1.06) as compared to a 24-35 month inter-pregnancy interval, respectively. The strength of both teenage pregnancy and short birth interval associations showed substantial variation across WHO region. We estimate that 8.6% (6.9-10.3%) of stunted cases in the South Asian DHS sample would have been averted by jointly eliminating teen pregnancies and birth intervals less than 24 months, while only 3.6% (1.5-5.7%) of stunting cases would have prevented in the Middle East and North Africa sample.

CONCLUSIONS

Postponing the age of first birth and increasing inter-pregnancy intervals has the potential to significantly reduce the prevalence of stunting and improve child development in LMICs.

The association of birth order with later body mass index and blood pressure: a comparison between prospective cohort studies from the United Kingdom and Brazil

Background:

Previous studies have found greater adiposity and cardiovascular risk in first born children. The causality of this association is not clear. Examining the association in diverse populations may lead to improved insight.

Methods:

We examine the association between birth order and body mass index (BMI), systolic and diastolic blood pressure (SBP/DBP) in the 2004 Pelotas cohort from southern Brazil and the Avon Longitudinal Study of Parents and Children (ALSPAC) from Bristol, south-west England, restricting analysis to families with two children in order to remove confounding by family size.

Results:

No consistent differences in BMI, SBP or DBP were observed comparing first and second born children. Within the Pelotas 2004 cohort, first born females were thinner, with lower SBP and DBP; for example, mean difference in SBP comparing first with second born was −0.979 (95% confidence interval −2.901 to 0.943). In ALSPAC, first born females had higher BMI, SBP and DBP. In both cohorts, associations tended to be in the opposite direction in males, although no statistical evidence for gender interactions was found.

Conclusions:

The findings do not support an association between birth order and BMI or blood pressure. Differences to previous studies may be explained by differences in populations and/or confounding by family size in previous studies.

Birth order progressively affects childhood height

BACKGROUND

There is evidence suggesting that first-born children and adults are anthropometrically different to later-borns. Thus, we aimed to assess whether birth order was associated with changes in growth and metabolism in childhood.

METHODS

We studied 312 healthy prepubertal children: 157 first-borns and 155 later-borns. Children were aged 3-10 years, born 37-41 weeks gestation, and of birth weight appropriate-for-gestational-age. Clinical assessments included measurement of children's height, weight, fasting lipid and hormonal profiles and DEXA-derived body composition.

RESULTS

First-borns were taller than later-borns (P < 0·0001), even when adjusted for parents' heights (0·31 vs 0·03 SDS; P = 0·001). There was an incremental height decrease with increasing birth order, so that first-borns were taller than second-borns (P < 0·001), who were in turn taller than third-borns (P = 0·007). Further, among sibling pairs both height SDS (P = 0·009) and adjusted height SDS (P < 0·0001) were lower in second- vs first-born children. Consistent with differences in stature, first- (P = 0·043) and second-borns (P = 0·003) had higher IGF-I concentrations than third-borns. Both first- (P < 0·001) and second-borns (P = 0·004) also had reduced abdominal adiposity (lower android fat to gynoid fat ratio) when compared with third-borns. Other parameters of adiposity and blood lipids were unaffected by birth order.

CONCLUSIONS

First-borns were taller than later-born children, with an incremental height reduction from first to third birth order. These differences were present after correction for genetic height, and associated to some extent with alterations in plasma IGF-I. Our findings strengthen the evidence that birth order is associated with phenotypic changes in childhood.

Maternal height and child growth patterns

OBJECTIVE

To examine associations between maternal height and child growth during 4 developmental periods: intrauterine, birth to age 2 years, age 2 years to mid-childhood (MC), and MC to adulthood.

STUDY DESIGN

Pooled analysis of maternal height and offspring growth using 7630 mother-child pairs from 5 birth cohorts (Brazil, Guatemala, India, the Philippines, and South Africa). We used conditional height measures that control for collinearity in height across periods. We estimated associations between maternal height and offspring growth using multivariate regression models adjusted for household income, child sex, birth order, and study site.

RESULTS

Maternal height was associated with birth weight and with both height and conditional height at each age examined. The strongest associations with conditional heights were for adulthood and 2 years of age. A 1-cm increase in maternal height predicted a 0.024 (95% CI: 0.021-0.028) SD increase in offspring birth weight, a 0.037 (95% CI: 0.033-0.040) SD increase in conditional height at 2 years, a 0.025 (95% CI: 0.021-0.029 SD increase in conditional height in MC, and a 0.044 (95% CI: 0.040-0.048) SD increase in conditional height in adulthood. Short mothers (<150.1 cm) were more likely to have a child who was stunted at 2 years (prevalence ratio = 3.20 (95% CI: 2.80-3.60) and as an adult (prevalence ratio = 4.74, (95% CI: 4.13-5.44). There was no evidence of heterogeneity by site or sex.

CONCLUSION

Maternal height influences offspring linear growth over the growing period. These influences likely include genetic and non-genetic factors, including nutrition-related intergenerational influences on growth that prevent the attainment of genetic height potential in low- and middle-income countries.