First-borns carry a higher metabolic risk in early adulthood: evidence from a prospective cohort study

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.

Exploring the effects of birth order on human lifespan in Polish historical populations, 1738–1968

While the relationships between birth order and later outcomes in life, including health and wealth, have been the subject of investigation for several decades, little or no data exist regarding the relationship between birth order and life expectancy in the Polish population. The aim of this study was to explore the link between birth order and lifespan in Polish historical populations. We obtained 8523 records from a historical dataset that was established for parishioners from the borough of Bejsce, including 4463 males and 4060 females. These data pertain to the populations that lived over a long period in a group of localities for which parish registers were well preserved. The Mann-Whitney U test, the Kruskal-Wallis ANOVA and ANCOVA were run. The results strongly suggest that birth order affects male longevity. However, no such association was found for females. On balance, the hypothesis that first-born boys live longer because they are born to relatively younger parents has received some empirical support and deserves further study. We hypothesise that the effects of birth order on human health and lifespan might be overshadowed by other factors, including educational attainment, socioeconomic status and lifestyle.

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.

Family Size and the Age at Infancy-Childhood Transition Determine a Child's Compromised Growth in Large Families

BACKGROUND

Data on growth of Israeli school children show that children from Jewish ultra-orthodox Haredi and Bedouin Arab families have a higher prevalence of stature below the 3rd percentile. While these populations are usually from lower socioeconomic strata, they also have larger families. This study aimed to evaluate if family structure and the timing of a child's infancy-childhood transition (ICT) are central to variations in stature.

STUDY DESIGN

We analyzed the association between family size, birth order and inter-birth interval with child growth and the age at ICT in 3 groups of children, 148 high birth order children from large families (LF ≥ 6), 118 low birth order children from large families (LF ≤ 3) and 150 children from small families (SF).

RESULTS

High birth order children from large families were shorter in childhood than children from small families with a difference of 0.5 SDS in length. We found that birth length and birth order explained 35% of the total variance in infancy length whereas ICT age and infancy length explained 72% of the total variance in childhood length.

CONCLUSION

Infancy and childhood length are compromised in children from large families. As the family grows larger the younger children tend to be shorter. Reduced length gain in the period between infancy to childhood is when growth is most affected.

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.

Sibling rank and sibling number in relation to cardiovascular disease and mortality risk: a nationwide cohort study

BACKGROUND

The number and rank order of siblings could be of importance for risk of cardiovascular disease and mortality. Previous studies have used only fatal events for risk prediction. We, therefore, aimed to use also non-fatal coronary and cardiovascular events in fully adjusted models.

METHODS

From the Multiple-Generation Register in Sweden, data were used from 1.36 million men and 1.32 million women (born 1932-1960), aged 30-58 years at baseline and with follow-up from 1990 to 2015. Mean age at follow-up was 67 years (range 55-83 years). Fatal and non-fatal events were retrieved from national registers.

RESULTS

Compared with men with no siblings, those with 1-2 siblings had a lower, and those with four or more siblings had a higher adjusted risk of cardiovascular events. Again, compared with men with no siblings, those with more than one sibling had a lower total mortality risk, and those with three or more siblings had an increased risk of coronary events.Correspondingly, compared with women with no siblings those women with three siblings or more had an increased risk of cardiovascular events, and those with two siblings or more had an increased risk of coronary events. Women with one sibling or more were at lower total mortality risk, following full adjustment.

CONCLUSION

Being first born is associated with a favourable effect on non-fatal cardiovascular and coronary events for both men and women. The underlying biological mechanisms for this should be studied in a sociocultural context.

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.

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'.

Large-for-gestational-age phenotypes and obesity risk in adulthood: a study of 195,936 women

While there is evidence that being born large-for-gestational-age (LGA) is associated with an increased risk of obesity later in life, the data are conflicting. Thus, we aimed to examine the associations between proportionality at birth and later obesity risk in adulthood. This was a retrospective study using data recorded in the Swedish Birth Register. Anthropometry in adulthood was assessed in 195,936 pregnant women at 10-12 weeks of gestation. All women were born at term (37-41 weeks of gestation). LGA was defined as birth weight and/or length ≥2.0 SDS. Women were separated into four groups: appropriate-for-gestational-age according to both weight and length (AGA - reference group; n = 183,662), LGA by weight only (n = 4,026), LGA by length only (n = 5,465), and LGA by both weight and length (n = 2,783). Women born LGA based on length, weight, or both had BMI 0.12, 1.16, and 1.08 kg/m² greater than women born AGA, respectively. The adjusted relative risk (aRR) of obesity was 1.50 times higher for those born LGA by weight and 1.51 times for LGA by both weight and height. Length at birth was not associated with obesity risk. Similarly, women born LGA by ponderal index had BMI 1.0 kg/m² greater and an aRR of obesity 1.39 times higher than those born AGA. Swedish women born LGA by weight or ponderal index had an increased risk of obesity in adulthood, irrespective of their birth length. Thus, increased risk of adult obesity seems to be identifiable from birth weight and ignoring proportionality.

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.

Prevalence and risk factors for hypertension among school children in Ilorin, Northcentral Nigeria

BACKGROUND

The global prevalence of childhood hypertension has increased from 1% to 2% to 4%-5%, with a value as high as 9.8% reported in Nigeria. However, the various risk factors associated with childhood hypertension in Nigeria are less explored. The aim of this study was to determine the prevalence of hypertension and related risk factors (sociodemographic, family history of hypertension, history of snoring, birth order, and anthropometric indices) in primary school children in Nigeria.

MATERIALS AND METHODS

A total of 1745 school children aged 6-12 years were selected using systematic random sampling method. Blood pressure (BP) was measured using the fourth report guideline. Those with BP higher than 90^th percentile had repeated BP measurements on two more occasions (2 and 4 weeks after initial measurement). Relevant history was obtained, and anthropometric measurements were taken by the standard methods. Data were analyzed using SPSS version 20.

RESULTS

Prevalence of systolic and or diastolic hypertension at the third visit was 3.0%. Prevalence of systolic hypertension (3^rd visit) was more in females (3.3%) than males (1.3%), P = 0.004. Prevalence of diastolic hypertension (3^rd visit) was higher in females (1.4%) than males (0.3%), P = 0.019. Hypertension showed no significant relationship with socioeconomic class, family history of hypertension, birth order, and history of snoring. Of the anthropometric indices (weight, height, body mass index (BMI), hip circumference, waist circumference, waist-to-hip ratio, and waist-to-height ratio, and only obesity (BMI ≥ 95^th centile) was related with hypertension (odd ratio 8.3, 95% confidence interval 1.7, 40.3).

CONCLUSIONS

Prevalence of hypertension is low (3.0%), and only obesity (BMI ≥ 95^th centile) is associated with hypertension.

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.

Life history trade-offs and the partitioning of maternal investment: Implications for health of mothers and offspring

Lay Summary: This review sets out the hypothesis that life history trade-offs in the maternal generation favour the emergence of similar trade-offs in the offspring generation, mediated by the partitioning of maternal investment between pregnancy and lactation, and that these trade-offs help explain widely reported associations between growth trajectories and NCD risk. Growth patterns in early life predict the risk of non-communicable diseases (NCDs), but adaptive explanations remain controversial. It is widely assumed that NCDs occur either because of physiological adjustments to early constraints, or because early ecological cues fail to predict adult environmental conditions (mismatch). I present an inter-generational perspective on developmental plasticity, based on the over-arching hypothesis that a key axis of variability in maternal metabolism derives from life history trade-offs, which influence how individual mothers partition nutritional investment in their offspring between pregnancy and lactation. I review evidence for three resulting predictions: (i) Allocating relatively more energy to growth during development promotes the capacity to invest in offspring during pregnancy. Relevant mechanisms include greater fat-free mass and metabolic turnover, and a larger physical space for fetal growth. (ii) Allocating less energy to growth during development constrains fetal growth of the offspring, but mothers may compensate by a tendency to attain higher adiposity around puberty, ecological conditions permitting, which promotes nutritional investment during lactation. (iii) Since the partitioning of maternal investment between pregnancy and lactation impacts the allocation of energy to 'maintenance' as well as growth, it is expected to shape offspring NCD risk as well as adult size and body composition. Overall, this framework predicts that life history trade-offs in the maternal generation favour the emergence of similar trade-offs in the offspring generation, mediated by the partitioning of maternal investment between pregnancy and lactation, and that these trade-offs help explain widely reported associations between growth trajectories and NCD risk.

Nulliparity is associated with subtle adverse metabolic outcomes in overweight/obese mothers and their offspring

BACKGROUND

We aimed to evaluate metabolic outcomes in overweight/obese nulliparous and multiparous women and their offspring.

STUDY DESIGN

Seventy-two overweight and obese women who participated in a randomized controlled trial of exercise in pregnancy were included in the study, comparing 18 nulliparous and 54 multiparous women and their singleton offspring. Women were assessed at 19 and 36 weeks of gestation. Fetal growth was measured using standard obstetric ultrasound techniques. Cord blood was collected at birth. Maternal and offspring body composition was assessed using DXA ~2 weeks after delivery.

RESULTS

Nulliparous women had higher HbA1c in the third trimester of pregnancy than multiparous women (5.48% vs 5.29%; P=.002) and were more insulin-resistant based on the surrogate marker sex hormone-binding globulin (354 vs 408 nmol/L; P=.047). Nulliparous women also had higher levels of the inflammatory marker tumour necrosis factor-alpha (4.74 vs 3.62 pg/mL; P=.025). At birth, the offspring of nulliparous women were on average 340 g (P=.013) and 0.69 standard deviation scores (P=.026) lighter than those born of multiparous women. Cord blood data showed lower insulin-like growth factor-II (P=.026) and higher IGF binding protein-1 (P=.002) levels in the offspring of nulliparous women. In addition, a less favourable metabolic profile was observed in the offspring of nulliparous women, as indicated by higher triglyceride (P<.001) and interleukin-6 (P=.039) concentrations.

CONCLUSIONS

Infants born of nulliparous overweight and obese women appear to be exposed to a less favourable metabolic environment in utero, with evidence of subtle adverse metabolic outcomes at birth compared to infants of overweight/obese multiparous women.

BIRTH ORDER, STAGE OF INFANCY AND INFANT MORTALITY IN INDIA

Using data from India's National Family Health Survey, 2005-06 (NFHS-3), this article examines the patterns of relationship between birth order and infant mortality. The analysis controls for a number of variables, including mother's characteristics such as age at the time of survey, current place of residence (urban/rural), years of schooling, religion, caste, and child's sex and birth weight. A modest J-shaped relationship between birth order of children and their risk of dying in the neonatal period is found, suggesting that although both first- and last-born children are at a significantly greater risk of dying compared with those in the middle, last-borns (i.e. fourth and higher order births) are at the worst risk. However, in the post-neonatal period first-borns are not as vulnerable, but the risk increases steadily with the addition of successive births and last-borns are at much greater risk, even worse than those in the neonatal period. Although the strength of relationship between birth order and mortality is attenuated after the potential confounders are taken into account, the relationship between the two variables remains curvilinear in the neonatal period and direct in the post-neonatal period. There are marked differences in these patterns by the child's sex. While female children are less prone to the risk of dying in the neonatal period in comparison with male children, the converse is true in the post-neonatal period. Female children not only run higher risks of dying in the post-neonatal period, but also become progressively more vulnerable with an increase in birth order.

Objectively-measured physical activity in children is influenced by social indicators rather than biological lifecourse factors: Evidence from a Brazilian cohort

The aim of this study was to examine the longitudinal influences of early life social and biological indicators on objectively measured physical activity. All newborns in 2004 in the city of Pelotas, Southern Brazil were enrolled in a birth cohort study. At the age of 6years, a follow-up visit included objective assessment of overall physical activity (summarized in milli-g, 1mg=0.001g) by tri-axial wrist worn accelerometry. The associations between early life exposures, such as type of delivery, parity, birth weight, preterm delivery, maternal physical activity, socioeconomic position, and overall physical activity were examined. Valid accelerometry data were obtained from 2604 children (78.2% of the eligible individuals). Girls were less active than boys (β=-8.65mg; 95% CI -10.0; -7.30). Higher socioeconomic position was related to lower activity levels (β=-9.69mg. 95% CI -12.45; -6.93) and a similar association was found with maternal schooling. No associations were found with birthweight, type of delivery or preterm delivery. This study provides evidence for the role of some social factors in explaining children's physical activity behaviors, and minimizes the influence of some early life biological factors at determining physical activity levels.

Association between ratio indexes of body composition phenotypes and metabolic risk in Italian adults

The ratio between fat mass (FM) and fat-free mass (FFM) has been used to discriminate individual differences in body composition and improve prediction of metabolic risk. Here, we evaluated whether the use of a visceral adipose tissue-to-fat-free mass index (VAT:FFMI) ratio was a better predictor of metabolic risk than a fat mass index to fat-free mass index (FMI:FFMI) ratio. This is a cross-sectional study including 3441 adult participants (age range 18-81; men/women: 977/2464). FM and FFM were measured by bioelectrical impedance analysis and VAT by ultrasonography. A continuous metabolic risk Z score and harmonised international criteria were used to define cumulative metabolic risk and metabolic syndrome (MetS), respectively. Multivariate logistic and linear regression models were used to test associations between body composition indexes and metabolic risk. In unadjusted models, VAT:FFMI was a better predictor of MetS (OR 8.03, 95%CI 6.69-9.65) compared to FMI:FFMI (OR 2.91, 95%CI 2.45-3.46). However, the strength of association of VAT:FFMI and FMI:FFMI became comparable when models were adjusted for age, gender, clinical and sociodemographic factors (OR 4.06, 95%CI 3.31-4.97; OR 4.25, 95%CI 3.42-5.27, respectively). A similar pattern was observed for the association of the two indexes with the metabolic risk Z score (VAT:FFMI: unadjusted b = 0.69 ± 0.03, adjusted b = 0.36 ± 0.03; FMI:FFMI: unadjusted b = 0.28 ± 0.028, adjusted b = 0.38 ± 0.02). Our results suggest that there is no real advantage in using either VAT:FFMI or FMI:FFMI ratios as a predictor of metabolic risk in adults. However, these results warrant confirmation in longitudinal studies.

Effect of the INSIGHT Responsive Parenting Intervention on Rapid Infant Weight Gain and Overweight Status at Age 1 Year: A Randomized Clinical Trial

IMPORTANCE

Rapid infant weight gain is associated with later obesity, but interventions to prevent rapid infant growth and reduce risk for overweight status in infancy are lacking.

OBJECTIVE

To examine the effect of a responsive parenting (RP) intervention on infant weight gain between birth and 28 weeks and overweight status at age 1 year.

DESIGN, SETTING, AND PARTICIPANTS

The Intervention Nurses Start Infants Growing on Healthy Trajectories (INSIGHT) study is an ongoing randomized clinical trial comparing an RP intervention designed to prevent childhood obesity with a safety control. The study includes primiparous mother-newborn dyads (n = 291) and was conducted at the Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania, in addition to home visits. Enrollment was initiated in January 2012, and evaluable population analyses for this study were conducted between April 2015 and November 2015.

INTERVENTIONS

At 2 weeks post partum, initial intervention materials appropriate to the assigned treatment group were mailed to the participant's home. Research nurses conducted home visits at 3 weeks, 16 weeks, 28 weeks, and 40 weeks, and a research center visit occurred at 1 year. The Intervention Nurses Start Infants Growing on Healthy Trajectories curriculum included messages about infant feeding, sleep hygiene, active social play, emotion regulation, and growth record education. The control group received a developmentally appropriate home safety intervention also delivered by nurse home visitors.

MAIN OUTCOMES AND MEASURES

Conditional weight gain from birth to 28 weeks was calculated. General linear models examined intervention effect on conditional weight gain. The intervention's effect on infant weight-for-length percentiles was tested using analysis of variance. Logistic regression compared the odds of overweight status (weight for length ≥95th percentile) at 1 year as a function of conditional weight gain.

RESULTS

Of the mothers included in the study, 246 were white (88%), 260 were non-Hispanic (93%), 210 were married (75%), and 201 were working full time (72%) at time of enrollment. The mean conditional weight gain score was lower among infants in the RP group compared with the control group (-0.18; 95% CI, -0.36 to -0.001), reflecting that the RP infants gained weight more slowly than control group infants (0.18; 95% CI, 0.02-0.34); this effect did not differ by feeding mode (predominantly fed breast milk or not). Infants in the RP group also had lower mean weight-for-length percentiles at 1 year than infants in the control group (57.5%; 95% CI, 52.56%-62.37% vs 64.4%; 95% CI, 59.94%-69.26%; P = .04) and were less likely to be overweight at age 1 year (5.5% vs 12.7%; P = .05).

CONCLUSIONS AND RELEVANCE

An RP intervention is associated with reduced rapid weight gain during the first 6 months after birth and overweight status at age 1 year.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01167270.

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.

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.

Age-related changes in basal substrate oxidation and visceral adiposity and their association with metabolic syndrome

PURPOSE

Ageing is directly associated with visceral fat (VAT) deposition and decline of metabolically active cellular mass, which may determine age-related shifts in substrate oxidation and increased cardiometabolic risk. We tested whether VAT and fasting respiratory quotient (RQ, an index of macronutrient oxidation) changed with age and if they were associated with increased risk of metabolic syndrome (MetSyn).

METHODS

A total of 2819 adult participants (age range: 18-81 years; men/women: 894/1925) were included; we collected history, anthropometric measures, biochemistry, smoking habits, and physical activity. The body mass index range was 18.5-60.2 kg/m(2). Gas exchanges (VO2 and VCO2) were measured by indirect calorimetry in fasting conditions, and RQ was calculated. Body composition was measured by bioelectrical impedance. Abdominal subcutaneous fat and VAT were measured by ultrasonography. MetSyn was diagnosed using harmonised international criteria. Multivariate linear and logistic regression models were utilised.

RESULTS

VAT increased with age in both men (r = 0.31, p < 0.001) and women (r = 0.37, p < 0.001). Basal RQ was not significantly associated with age (p = 0.49) and VAT (p = 0.20); in addition, basal RQ was not a significant predictor of MetSyn (OR 3.31, 0.57-19.08, p = 0.27). VAT was the primary predictor of MetSyn risk in a fully adjusted logistic model (OR 4.25, 3.01-5.99, p < 0.001).

CONCLUSIONS

Visceral adiposity remains one of the most important risk factors for cardiometabolic risk and is a significant predictor of MetSyn. Post-absorptive substrate oxidation does not appear to play a significant role in age-related changes in body composition and cardiometabolic risk, except for a correlation with triglyceride concentration.

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.

A new birthweight reference in Guangzhou, southern China, and its comparison with the global reference

OBJECTIVE

To formulate a new birthweight reference for different gestational ages in Guangzhou, southern China, and compare it with the currently used reference in China and the global reference.

DESIGN AND SETTING

All singleton live births of more than 26 weeks' gestational age recorded in the Guangzhou Perinatal Health Care and Delivery Surveillance System for the years 2009, 2010 and 2011 (n=510 837) were retrospectively included in the study. In addition, the study sample was supplemented by all singleton live births (n=3538) at gestational ages 26-33 weeks from 2007 and 2008. We used Gaussian mixture models and robust regression to exclude outliers of birth weight and then applied Generalized Additive Models for Location, Scale, and Shape (GAMLSS) to generate smoothed percentile curves separately for gender and parity.

RESULTS

Of infants defined as small for gestational age (SGA) in the new reference, 15.3-47.7% (depending on gestational age) were considered appropriate for gestational age (AGA) by the currently used reference of China. Of the infants defined as SGA by the new reference, 9.2% with gestational ages 34-36 weeks and 14.3% with 37-41 weeks were considered AGA by the global reference. At the 50th centile line, the new reference curve was similar to that of the global reference for gestational ages 26-33 weeks and above the global reference for 34-40 weeks.

CONCLUSIONS

The new birthweight reference based on birthweight data for neonates in Guangzhou, China, differs from the reference currently used in China and the global reference, and appears to be more relevant to the local population.

Maternal smoking during pregnancy and growth in infancy: a covariance structure analysis

Background

Smoking during pregnancy is related to fetal constraint and accelerated postnatal growth. However, the pathways between these factors have not been clarified. Pathway analyses that link these factors can help us better understand the mechanisms involved in this association. Therefore, this study aimed to examine pathways between maternal smoking during pregnancy and growth in infancy.

Methods

Participants were singletons born between 1993 and 2006 in rural Japan. The outcome was the change in weight z-score between birth and 3 years of age. Pathways from maternal smoking and other maternal factors (such as maternal body mass index and work status) to growth in infancy via birth factors (such as birth weight and gestational age) and breastfeeding were examined using structural equation modeling.

Results

Complete data were available for 1524 children (775 boys and 749 girls). The model fit appeared adequate. Lower birth weight and non-exclusive breastfeeding mediated the association between maternal smoking during pregnancy and rapid growth in infancy. Maternal smoking was also directly linked to rapid growth in infancy (standardized direct effects 0.06, P = 0.002). Taking all pathways into account, the standardized total effect of maternal smoking on growth in infancy was 0.11.

Conclusions

Maternal smoking during pregnancy may both indirectly, through birth weight and breastfeeding status, and directly influence growth during infancy; however, there may be other pathways that have not yet been identified.

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.

Among overweight middle-aged men, first-borns have lower insulin sensitivity than second-borns

We aimed to assess whether birth order affects metabolism and body composition in overweight middle-aged men. We studied 50 men aged 45.6 ± 5.5 years, who were overweight (BMI 27.5 ± 1.7 kg/m(2)) but otherwise healthy in Auckland, New Zealand. These included 26 first-borns and 24 second-borns. Insulin sensitivity was assessed by the Matsuda method from an oral glucose tolerance test. Other assessments included DXA-derived body composition, lipid profiles, 24-hour ambulatory blood pressure, and carotid intima-media thickness. First-born men were 6.9 kg heavier (p = 0.013) and had greater BMI (29.1 vs 27.5 kg/m(2); p = 0.004) than second-borns. Insulin sensitivity in first-born men was 33% lower than in second-borns (4.38 vs 6.51; p = 0.014), despite adjustment for fat mass. There were no significant differences in ambulatory blood pressure, lipid profile or carotid intima-media thickness between first- and second-borns. Thus, first-born adults may be at a greater risk of metabolic and cardiovascular diseases.

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.

Association of birth order with cardiovascular disease risk factors in young adulthood: a study of one million Swedish men

Background

Birth order has been suggested to be linked to several cardiovascular disease (CVD) risk factors, but the evidence is still inconsistent. We aim to determine the associations of birth order with body mass index (BMI), muscle strength and blood pressure. Further we will analyse whether these relationships are affected by family characteristics.

Methods

BMI, elbow flexion, hand grip and knee extension strength and systolic and diastolic blood pressure were measured at conscription examination in 1 065 710 Swedish young men born between 1951 and 1975. The data were analysed using linear multivariate and fixed effects regression models; the latter compare siblings and account for genetic and social factors shared by brothers.

Results

Fixed effect regression analysis showed that birth order was inversely associated with BMI: second and third born had 0.8% and 1.1% (p<0.001) lower BMI than first-born, respectively. The association pattern differed among muscle strengths. After adjustment for BMI, first-born presented lower elbow flexion and hand grip strength than second-born (−5.9 N and −3.8 N, respectively, p<0.001). Knee extension strength was inversely related to birth order though not always significantly. The association between birth order and blood pressure was not significant.

Conclusions

Birth order is negatively associated with BMI and knee extension strength, positively with elbow flexion and hand grip strength, and is not associated with blood pressure among young men. Although the effects are small, the link between birth order and some CVD risk factors is already detectable in young adulthood.

Being an only or last-born child increases later risk of obesity

BACKGROUND

Studies have suggested that number of siblings and birth order is associated with obesity. However, studies combining these exposures are needed. This study aimed at investigating obesity in children and young adults in regard to different combinations of family size and birth order.

METHODS

Two cohorts selected from the general population were investigated: The Copenhagen School Health Records Register (CSHRR) and a Draft Board (DB) sample with measured heights and weights in childhood (age 13 years) and young adulthood (age 19 years), respectively. Information on birth order, number of siblings, and relevant covariates were available on 29 327 children, as well as on 323 obese young men and 575 randomly selected controls of young men representing approximately 58 000. The relation between number of siblings and birth order, respectively, and having a Body Mass Index (BMI) z-score above or equal to the 95(th) percentile in childhood or having a BMI of at least 31.00 kg/m(2) in young adulthood was analysed using logistic regression analyses adjusted for relevant confounders.

RESULTS

Only children had significantly higher odds of obesity both in childhood and in young adulthood compared with children with siblings, odds ratio (OR) =1.44 (95% Confidence Interval (CI): 1.26-1.66) and OR=1.76 (95% CI: 1.18-2.61), respectively. No association between first-born status and obesity was found. The OR of last-born children being obese was also significantly increased in childhood, e.g. OR=1.93 (95% CI: 1.09-3.43) of obesity if last-born in a family of four children. This was not found in young adulthood. Additionally, higher spacing to previous sibling (average 1872 vs. 1303 days; p=0.026 in four children families) was observed in obese last-born compared to non-obese last-born children.

CONCLUSION

Being an only or last-born child is associated with obesity. These associations may provide leads to targeted prevention of obesity in children.

Fetal growth versus birthweight: the role of placenta versus other determinants

Introduction

Birthweight is used as an indicator of intrauterine growth, and determinants of birthweight are widely studied. Less is known about determinants of deviating patterns of growth in utero. We aimed to study the effects of maternal characteristics on both birthweight and fetal growth in third trimester and introduce placental weight as a possible determinant of both birthweight and fetal growth in third trimester.

Methods

The STORK study is a prospective cohort study including 1031 healthy pregnant women of Scandinavian heritage with singleton pregnancies. Maternal determinants (age, parity, body mass index (BMI), gestational weight gain and fasting plasma glucose) of birthweight and fetal growth estimated by biometric ultrasound measures were explored by linear regression models. Two models were fitted, one with only maternal characteristics and one which included placental weight.

Results

Placental weight was a significant determinant of birthweight. Parity, BMI, weight gain and fasting glucose remained significant when adjusted for placental weight. Introducing placental weight as a covariate reduced the effect estimate of the other variables in the model by 62% for BMI, 40% for weight gain, 33% for glucose and 22% for parity. Determinants of fetal growth were parity, BMI and weight gain, but not fasting glucose. Placental weight was significant as an independent variable. Parity, BMI and weight gain remained significant when adjusted for placental weight. Introducing placental weight reduced the effect of BMI on fetal growth by 23%, weight gain by 14% and parity by 17%.

Conclusion

In conclusion, we find that placental weight is an important determinant of both birthweight and fetal growth. Our findings indicate that placental weight markedly modifies the effect of maternal determinants of both birthweight and fetal growth. The differential effect of third trimester glucose on birthweight and growth parameters illustrates that birthweight and fetal growth are not identical entities.

Review: Placenta, evolution and lifelong health

The intrauterine environment has an important influence on lifelong health, and babies who grew poorly in the womb are more likely to develop chronic diseases in later life. Placental function is a major determinant of fetal growth and is therefore also a key influence on lifelong health. The capacity of the placenta to transport nutrients to the fetus and regulate fetal growth is determined by both maternal and fetal signals. The way in which the placenta responds to these signals will have been subject to evolutionary selective pressures. The responses selected are those which increase Darwinian fitness, i.e. reproductive success. This review asks whether in addition to responding to short-term signals, such as a rise in maternal nutrient levels, the placenta also responds to longer-term signals representing the mother's phenotype as a measure of environmental influences across her life course. Understanding how the placenta responds to maternal signals is therefore not only important for promoting optimal fetal growth but can also give insights into how human evolution affected developmental history with long-term effects on health and disease.

Fat and fat-free mass at birth: air displacement plethysmography measurements on 350 Ethiopian newborns

LBW increases the risk of a number of noncommunicable diseases in adulthood. However, birth weight (BW) cannot describe variability in infant body composition (BC). Variability in fat mass (FM) and fat-free mass (FFM) at birth may be particularly important in low-income countries because they undergo nutritional transition. There is a need for data on birth BC and its predictors from low-income countries in transition. We assessed absolute FM and FFM at birth and examined the role of gender, parity, GA, and LBW as predictors of birth BC. FM and FFM were assessed within 48 h of birth on 350 Ethiopian newborns using air displacement plethysmography (ADP). Female gender and being an infant of primi- or secundiparous mothers predicted lower BW and lower birth FFM but not FM, compared with male gender and infants of multiparous mothers, respectively. There was a positive linear relationship between BW and relative amount of FM for boys and girls. This study presents reference data on birth FM and FFM from a low-income setting and provides background for further longitudinal mapping of the relationship between fetal BC, childhood growth, and adult disease.

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

Birth weight has been inversely associated with later blood pressure. Firstborns tend to have lower birth weight than their later-born peers, but the long-term consequences remain unclear. The study objective was to investigate differences between firstborn and later-born individuals in early growth patterns, body composition, and blood pressure in Brazilian adolescents. The authors studied 453 adolescents aged 13.3 years from the prospective 1993 Pelotas Birth Cohort. Anthropometry, blood pressure, physical activity by accelerometry, and body composition by deuterium were measured. Firstborns (n = 143) had significantly lower birth weight than later borns (n = 310). At 4 years, firstborns had significantly greater weight and height, indicating a substantial overshoot in catch-up growth. In adolescence, firstborns had significantly greater height and blood pressure and a lower activity level. The difference in systolic blood pressure could be attributed to variability in early growth and that in diastolic blood pressure to reduced physical activity. The magnitude of increased blood pressure is clinically significant; hence, birth order is an important developmental predictor of cardiovascular risk in this population. Firstborns may be more sensitive to environmental factors that promote catch-up growth, and this information could potentially be used in nutritional management to prevent catch-up “overshoot.”