Unravelling the fetal origins hypothesis: is there really an inverse association between birthweight and subsequent blood pressure?

Birth weight and adolescent blood pressure measured at age 12 years in the Gateshead Millennium Study

Birth weight and early growth have been associated with later blood pressure. However, not all studies consistently find a significant reduction in blood pressure with an increase in birth weight. In addition, the relative importance of birth weight and of other lifestyle and environmental factors is often overlooked and the association is rarely studied in adolescents. We investigated early life predictors, including birth weight, of adolescent blood pressure in the Gateshead Millennium Study (GMS). The GMS is a cohort of 1029 individuals born in 1999-2000 in Gateshead in Northern England. Throughout infancy and early childhood, detailed information were collected, including birth weight and measures of height and weight. Assessments of 491 returning participants at age 12 years included measures of body mass and blood pressure. Linear regression and path analysis were used to determine predictors and their relative importance on blood pressure. Birth weight was not directly associated with blood pressure at the age of 12. However, after adjustment for contemporaneous body mass index (BMI), an inverse association of standardized birth weight on systolic blood pressure was significant. The relative importance of birth weight on later systolic blood pressure was smaller than other contemporaneous body measures (height and BMI). There was no independent association of birth weight on blood pressure seen in this adolescent population. Contemporaneous body measures have an important role to play. Lifestyle factors that influence body mass or size, such as diet and physical activity, where interventions are directed at early prevention of hypertension should be targeted.

Prospective cohort studies of birth weight and risk of obesity, diabetes, and hypertension in adulthood among the Chinese population

BACKGROUND

Low birth weight (LBW) has been associated with subsequent risks of obesity and certain chronic diseases, but evidence for the associations is limited for the Chinese population.

METHODS

In this study we analyzed data from two population-based prospective cohort studies, the Shanghai Women's Health Study and the Shanghai Men's Health Study, to examine the associations between LBW and the risk of obesity and chronic diseases. Birth weight was self-reported at baseline; anthropometric measurements were made at study enrollment. Type 2 diabetes mellitus (T2DM) diagnoses were self-reported, whereas hypertension diagnoses were based on self-report and blood pressure measurements at baseline and follow-up surveys.

RESULTS

Birth weight was available for 11 515 men and 13 569 women. Non-linear associations were observed for birth weight with baseline body mass index (BMI), waist circumference (WC), waist:  hip ratio (WHR), and waist:  height ratio (WHtR; P < 0.05 for non-linearity), and LBW was linked with lower BMI, smaller WC, and larger WHR and WHtR. An excess risk of T2DM was observed for LBW (<2500 g) versus birth weight 2500-3499 g since baseline (hazard ratio [HR] 1.17; 95% confidence interval [CI] 0.92-1.49) and since birth (HR 1.29; 95% CI 1.07-1.54), whereas the HRs for hypertension since baseline and birth were 1.13 (95% CI 1.01-1.27) and 1.20 (95% CI 1.11-1.30), respectively. The risk of the diseases decreased as birth weight increased up to ~4000 g; further increases in birth weight did not convey additional benefits.

CONCLUSION

The results suggest that LBW, an index of poor intrauterine nutrition, may affect health risks later in life in the Chinese population.

Fetal Origins of Mental Disorders? An Answer Based on Mendelian Randomization

The Barker hypothesis states that low birth weight (BW) is associated with higher risk of adult onset diseases, including mental disorders like schizophrenia, major depressive disorder (MDD), and attention deficit hyperactivity disorder (ADHD). The main criticism of this hypothesis is that evidence for it comes from observational studies. Specifically, observational evidence does not suffice for inferring causality, because the associations might reflect the effects of confounders. Mendelian randomization (MR) - a novel method that tests causality on the basis of genetic data - creates the unprecedented opportunity to probe the causality in the association between BW and mental disorders in observation studies. We used MR and summary statistics from recent large genome-wide association studies to test whether the association between BW and MDD, schizophrenia and ADHD is causal. We employed the inverse variance weighted (IVW) method in conjunction with several other approaches that are robust to possible assumption violations. MR-Egger was used to rule out horizontal pleiotropy. IVW showed that the association between BW and MDD, schizophrenia and ADHD is not causal (all p > .05). The results of all the other MR methods were similar and highly consistent. MR-Egger provided no evidence for pleiotropic effects biasing the estimates of the effects of BW on MDD (intercept = -0.004, SE = 0.005, p = .372), schizophrenia (intercept = 0.003, SE = 0.01, p = .769), or ADHD (intercept = 0.009, SE = 0.01, p = .357). Based on the current evidence, we refute the Barker hypothesis concerning the fetal origins of adult mental disorders. The discrepancy between our results and the results from observational studies may be explained by the effects of confounders in the observational studies, or by the existence of a small causal effect not detected in our study due to weak instruments. Our power analyses suggested that the upper bound for a potential causal effect of BW on mental disorders would likely not exceed an odds ratio of 1.2.

Gendered "Long Arm" of Parental Education? Life Course Influences on Later Life Functional Limitations in India

Objective: We adopt a novel approach to mediation analysis to account for interrelated life course social processes that constitute later life health disparities. We examine gender-specific direct effect of parental education on functional limitations in later life. Method: Based on the first wave (2007-2010; n = 7,150) of the Study on Global Ageing and Adult Health (SAGE), we estimate both (natural) direct and indirect effects of parental education on functional limitations in later life. Results: We observed a significant indirect and positive effect of parental education on functional health. Contrary to prior literature, we documented adverse direct effect of parental education on later life functional health. The direct effect is statistically significant only for father's education, and is greater, though not statistically significantly so, for women than men. Discussion: The intersection of gender status and interrelated social stratification documented by this study highlights the need for gender-sensitive life course research. Such research can enhance our understanding of the ways patriarchal social systems produce heterogeneous effects of interrelated structural factors on later life health for men and women.

It's the mother!: How assumptions about the causal primacy of maternal effects influence research on the developmental origins of health and disease

Research on the developmental origins of health and disease (DOHaD) has traditionally focused on how maternal exposures around the time of pregnancy might influence offspring health and risk of disease. We acknowledge that for some exposures this is likely to be correct, but argue that the focus on maternal pregnancy effects also reflects implicit and deeply-held assumptions that 1) causal early life exposures are primarily transmitted via maternal traits or exposures, 2) maternal exposures around the time of pregnancy and early infancy are particularly important, and 3) other factors, such as paternal factors and postnatal exposures in later life, have relatively little impact in comparison. These implicit assumptions about the "causal primacy" of maternal pregnancy effects set the agenda for DOHaD research and, through a looping effect, are reinforced rather than tested. We propose practical strategies to redress this imbalance through maintaining a critical perspective about these assumptions.

Association of preterm birth and small for gestational age with metabolic outcomes in children and adolescents: A population-based cohort study from Taiwan

BACKGROUND

Previous studies have identified preterm birth and/or small for gestational age (SGA) as risk factors for features of the metabolic syndrome, including high blood pressure, insulin sensitivity and atherosclerosis, occurring later in life, with controversial results. We conducted this population-based cohort study to investigate metabolic outcomes in those with former preterm birth and/or SGA status in Taiwan.

METHODS

Data were obtained from Taiwan's universal National Health Insurance Research Database. From 1996 to 2004, 37,119 preterm infants, 3386 SGA infants, and 162,020 matched controls were included. We investigated the risk of the metabolic disease, including hypertension, diabetes, and hyperlipidemia, which had been recorded by the end of 2008.

RESULTS

The preterm and SGA cohort, combined into one, had a significantly increased risk of developing metabolic disorders when compared with the comparison cohort (HR = 2.46, 95% CI = 2.02-3.01). We observed that children with former preterm and SGA status in Taiwan had a higher risk of developing hypertension (HR = 3.24, 95% CI = 1.58-6.67), Type 1 diabetes mellitus (HR = 1.80, 95% CI = 1.05-3.07), Type 2 diabetes mellitus (HR = 2.49, 95% CI = 1.98-3.14), and hyperlipidemia (HR = 2.14, 95% CI = 1.29-3.52).

CONCLUSION

Our study revealed the risk of metabolic disease in those with preterm birth and/or SGA. Further studies with a longer duration of follow-up are required to confirm if there is a tendency for the metabolic syndrome to develop in this study cohort.

Metabolic signatures of birthweight in 18 288 adolescents and adults

BACKGROUND

Lower birthweight is associated with increased susceptibility to cardiometabolic diseases in adulthood, but the underlying molecular pathways are incompletely understood. We examined associations of birthweight with a comprehensive metabolic profile measured in adolescents and adults.

METHODS

High-throughput nuclear magnetic resonance metabolomics and biochemical assays were used to quantify 87 circulating metabolic measures in seven cohorts from Finland and the UK, comprising altogether 18 288 individuals (mean age 26 years, range 15-75). Metabolic associations with birthweight were assessed by linear regression models adjusted for sex, gestational age and age at blood sampling. The metabolic associations with birthweight were compared with the corresponding associations with adult body mass index (BMI).

RESULTS

Lower birthweight adjusted for gestational age was adversely associated with cardiometabolic biomarkers, including lipoprotein subclasses, fatty acids, amino acids and markers of inflammation and impaired liver function (P < 0.0015 for 46 measures). Associations were consistent across cohorts with different ages at metabolic profiling, but the magnitudes were weak. The pattern of metabolic deviations associated with lower birthweight resembled the metabolic signature of higher adult BMI (R² = 0.77) assessed at the same time as the metabolic profiling. The resemblance indicated that 1 kg lower birthweight is associated with similar metabolic aberrations as caused by 0.92 units higher BMI in adulthood.

CONCLUSIONS

Lower birthweight adjusted for gestational age is associated with adverse biomarker aberrations across multiple metabolic pathways. Coherent metabolic signatures between lower birthweight and higher adult adiposity suggest that shared molecular pathways may potentially underpin the metabolic deviations. However, the magnitudes of metabolic associations with birthweight are modest in comparison to the effects of adiposity, implying that birthweight is only a weak indicator of the metabolic risk profile in adulthood.

Is birth weight associated with blood pressure among African children and adolescents? A systematic review

There is substantial evidence of an inverse association between birth weight and later blood pressure (BP) in populations from high-income countries, but whether this applies in low-income countries, where causes of low birth weight are different, is not certain.

OBJECTIVE

We conducted a review of the evidence on the relationship between birth weight and BP among African children and adolescents. Medline, EMBASE, Global Health and Web of Science databases were searched for publications to October 2016. Papers reporting the relationship between birth weight and BP among African children and adolescents were assessed. Bibliographies were searched for further relevant publications. Selected papers were summarized following the preferred reporting items for systematic review and meta-analysis (PRISMA) guidelines. In total, 16 papers from 13 studies conducted in nine African countries (Nigeria, Republic of Seychelles, Gambia, Democratic Republic of Congo, Cameroon, South Africa, Algeria, Zimbabwe and Angola) were reviewed. Eight studies were cohorts, while five were cross-sectional. The relationship between birth weight and later BP varied with age of the participants. Studies in neonates showed a consistently positive association, while predominantly inverse associations were seen among children, and studies in adolescents were inconsistent. Based on the limited number of studies identified, the relationship between birth weight and later BP may vary with age in African children and adolescents. Not all studies adequately controlled for confounding, notably gender or age. Whether the inverse relationship between birth weight and BP in later life observed in Western settings is also seen in Africa remains unclear.

Paternal exposure to medical-related radiation associated with low birthweight infants: A large population-based, retrospective cohort study in rural China

Low birthweight (LBW) is closely associated with fetal and perinatal mortality and morbidity. We identified the risk factors of LBW and geographical differences in LBW incidence in 30 Chinese provinces in the present study.This study was a population-based, retrospective cohort study performed in 30 Chinese provinces. We used data from the free National Pre-pregnancy Checkups Project, which is a countrywide population-based retrospective cohort study. To identify regional differences in LBW incidence, we used the Qinling-Huaihe climate line to divide China into northern and southern sections and the Heihe-Tengchong economic line to divide it into eastern and western sections. Multivariate unconditional logistic regression analysis with SAS 9.4 was used for data analysis. P < .05 was considered statistically significant.LBW incidence was 4.54% in rural China. Southern China had a significantly higher incidence (4.65%) than northern China (4.28%). Our main risk factor for LBW is paternal exposure to radiation (odds ratio = 1.537), which has never been studied before.This study identifies multiple risk factors of couples giving birth to LBW babies including paternal risk factors.

Birthweight and cardiometabolic risk patterns in multiracial children

BACKGROUND/OBJECTIVES

Prenatal growth, which is widely marked by birthweight, may have a pivotal role in affecting the lifelong risk of cardiometabolic disorders; however, comprehensive evaluation of its relations with childhood cardiometabolic risk patterns and the ethnic and gender disparities in national representative populations is still lacking. The aim of this study was to evaluate the associations between birthweight and comprehensive patterns of cardiometabolic risk in a nationally representative sample of children and adolescents.

SUBJECTS/METHODS

Prospective analyses were performed using data from 28 153 children 0 to 15 years in the National Health and Nutrition Examination Survey from 1999 through 2014. We defined childhood cardiometabolic disorders using standard definitions for obesity, high blood pressure, hyperglycemia and dyslipidemia.

RESULTS

Five birthweight categories <2.5, 2.5-3.0, 3.0-3.5, 3.5-4.2 and ⩾4.2 kg accounted for 8.2%, 17.9%, 35.7%, 27.9% and 10.4% of the population, respectively. In all children, with increasing birthweight, we observed significantly increasing trends of the risk of general and central obesity (P for trend <0.01) and significantly decreasing trends of the risk of high systolic blood pressure (SBP), high HbA1c and low high-density lipoprotein cholesterol (HDL-C) (P for trend <0.05). The associations were independent of current body mass index (BMI). In addition, we found that the relations of birthweight with high waist circumference in Black children showed U-shape, as well as high SBP in Mexican and Hispanic children. Moreover, we found that the associations of low birthweight with high SBP and low HDL-C appeared to more prominent significant in boys, whereas the inverse association with high HbA1c was more evident in girls.

CONCLUSIONS

Our data indicate that birthweight is significantly related to childhood cardiometabolic risk, independent of current BMI, and the associations exhibit race and gender-specific patterns.

Nutrition in the First 1000 Days: Ten Practices to Minimize Obesity Emerging from Published Science

The prevalence of childhood overweight and obesity has increased in most countries the last decades. Considering this in a simplistic way, we can say that obesity is the result of an imbalance between energy intake and energy expenditure. Moreover, the environment from conception to childhood could influence the child's future health. The first 1000 days of life start with woman's pregnancy, and offer a unique window of opportunity to contribute to obesity prevention. In light of the actual literature, the aim of our article is to discuss a proposal of 10 good practices to minimize obesity in the first 1000 days emerging from published science. (1) Both the mother's and the father's behaviors are important. A balanced diet with appropriate fat and protein intake, and favoring fruits and vegetables, is recommended for both parents during the conception period and pregnancy. Furthermore, overweight/obese women who are planning to become pregnant should reduce their weight before conception. (2) During pregnancy, at birth, and during early life, body composition measurements are crucial to monitor the baby's growth. (3) Exclusive breastfeeding is recommended at the beginning of life until six months of age. (4) Four to six months of age is the optimal window to introduce complementary feeding. Until one year of age, breast milk or follow-on/commercial formula is the main recommended feeding source, and cow's milk should be avoided until one year of age. (5) Fruit and vegetable introduction should begin early. Daily variety, diversity in a meal, and repeated exposure to the food, up to eight times, are efficient strategies to increase acceptance of food not well accepted at first. There is no need to add sugar, salt, or sugary fluids to the diet. (6) Respect the child's appetite and avoid coercive "clean your plate" feeding practices. Adapt the portion of food and don't use food as reward for good behavior. (7) Limit animal protein intake in early life to reduce the risk of an early adiposity rebound. Growing-up milk for children between one and three years of age should be preferred to cow's milk, in order to limit intake and meet essential fatty acid and iron needs. (8) The intake of adequate fat containing essential fatty acids should be promoted. (9) Parents should be role models when feeding, with TV and other screens turned-off during meals. (10) Preventive interventions consisting of promoting physical activity and sufficient time dedicated to sleep should be employed. In fact, short sleep duration may be associated with increased risk of developing obesity. Based on literature reviews, and given the suggestions described in this manuscript, concerted public health efforts are needed to achieve the healthy objectives for obesity and nutrition, and to fight the childhood obesity epidemic.

Birth Weight and Birth Weight for Gestational Age in Relation to Risk of Hospitalization with Primary Hypertension in Children and Young Adults

Introduction Low birth weight has been associated with an increased risk of hypertension in children. Less clear is whether high birth weight is also associated with risk. We evaluated overall and age-specific risks of primary hypertension in children and young adults associated with birth weight and birth weight for gestational age. Methods We conducted a population-based case-control study using linked Washington State birth certificate and hospital discharge data from 1987 to 2003. Cases were persons hospitalized with primary hypertension at 8-24 years of age (n = 533). Controls were randomly selected among those born in the same years who were not hospitalized with hypertension (n = 25,966). Results Birth weight was not related to risk of primary hypertension overall, except for a suggestion of an increased risk associated with birth weight ≥4500 g relative to 3500-3999 g (odds ratio (OR) 1.55; 95 % confidence interval (CI) 0.96-2.49). Compared to children born appropriate weight for gestational age, those born small (SGA) (OR 1.32; 95 % CI 1.02-1.71) and large for gestational age (LGA) (OR 1.30; 95 % CI 1.00-1.71) had increased risks of primary hypertension. These overall associations were due to increased risks of hypertension at 15-24 years of age; no associations were observed with risk at 8-14 years of age. Discussion In this study, both SGA and LGA were associated with increased risks of primary hypertension. Our findings suggest a possible nonlinear (U-shaped) association between birth weight for gestational age and primary hypertension risk in children and young adults.

Evaluating the Relationship Between Birth Weight for Gestational Age and Adult Blood Pressure Using Participants From a Cohort of Same-Sex Siblings, Discordant on Birth Weight Percentile

Many studies have described an inverse relationship between birth weight and blood pressure (BP). Debate continues, however, over the magnitude and validity of the association. This analysis draws on the Early Determinants of Adult Health study (2005-2008), a cohort of 393 US adults (mean age 43 years; 47% male), including 114 same-sex sibling pairs deliberately sampled to be discordant on sex-specific birth weight for gestational age (BW/GA) in order to minimize confounding in studies of fetal growth and midlife health outcomes. Every quintile increment in BW/GA percentile was associated with a 1.04-mm Hg decrement in adult systolic BP (95% confidence interval (CI): -2.14, 0.06) and a 0.63-mm Hg decrement in diastolic BP (95% CI: -1.35, 0.09), controlling for sex, age, site, smoking, and race/ethnicity. The relationship was strongest among those in the lowest decile of BW/GA. Adding adult body mass index to the models attenuated the estimates (e.g., to -0.90 mm Hg (95% CI: -1.94, 0.14) for systolic BP). In the sibling-pair subgroup, associations were slightly stronger but with wider confidence intervals (e.g., -1.22 mm Hg (95% CI: -5.20, 2.75) for systolic BP). In conclusion, we found a small inverse relationship between BW/GA and BP in cohort and sibling-pair analyses, but the clinical or public health significance is likely limited.

Association between Blood Pressure and Birth Weight among Rural South African Children: Ellisras Longitudinal Study

The aim of this cross-sectional study was to investigate the association between birth weight, underweight, and blood pressure (BP) among Ellisras rural children aged between 5 and 15 years. Data were collected from 528 respondents who participated in the Ellisras Longitudinal Study (ELS) and had their birth weight recorded on their health clinic card. Standard procedure was used to measure the anthropometric measurements and BP. Linear regression was used to assess BP, underweight variables, and birth weight. Logistic regression was used to assess the association of hypertension risks, low birth weight, and underweight. The association between birth weight and BP was not statistically significant. There was a significant (p < 0.05) association between mean BP and the sum of four skinfolds (β = 0.26, 95% CI 0.15-0.23) even after adjusting for age (β = 0.18, 95% CI 0.01-0.22). Hypertension was significantly associated with weight for age z-scores (OR = 5.13, 95% CI 1.89-13.92) even after adjusting for age and sex (OR = 5.26, 95% CI 1.93-14.34). BP was significantly associated with the sum of four skinfolds, but not birth weight. Hypertension was significantly associated with underweight. Longitudinal studies should confirm whether the changes in body weight we found can influence the risk of cardiovascular diseases.

Contribution of birth weight and adult waist circumference to cardiovascular disease risk in a longitudinal study

To determine the association of birth weight (BW) and waist circumference (WC) on cardiovascular disease (CVD). The longitudinal cohort study consisted of 745 participants who were able to provide their birth weight information and were followed from 2002 to 2014. During the follow-up, 83 events of CVD were confirmed. After adjusting for confounding factors, subjects with birth weight <2500 g were at a significantly increased CVD risk when compared to subjects with birth weight between 2500–3999 g (OR 2·47, 95%CI, 1·07–5·71). When high waist circumference (HWC), a measurement of adult obesity, was incorporated into stratifying factors according to presence or absence of low birth weight (LBW, birth weight <2500 g), adjusted CVD risk was significantly elevated in -LBW/+ HWC group (OR 1·94, 95%CI, 1·10–3·43) and marginally significantly increased in +LBW/-HWC group (OR 2·94, 95%CI, 1·00–8·64). CVD risk was highest in subjects with LBW and HWC (+LBW/+HWC), OR 4·74 (95%CI, 1·48–15·21). Higher waist circumference in adulthood is an especially strong risk factor for cardiovascular disease among those small at birth. In this cohort, birth size and adiposity in adulthood interact to predict events of cardiovascular disease.

Does the association between birth weight and blood pressure increase with age? A longitudinal study in young adults

OBJECTIVES

To assess whether the association between birth weight and blood pressure (BP) increases with age using three different statistical methods.

METHODS

A representative sample of 1232 study participants born between 1974-1978 in Limache, Chile were assessed in 2000-2002, of whom 796 were reassessed in 2010-2012. An 'amplification effect' was assessed by the change in the β coefficient in the two periods, the association between birth weight and the difference of BP overtime, and the interaction between birth weight and BP in the two periods.

RESULTS

Birth weight was negatively associated with SBP in 2000-2002 (β = -2.46, 95% confidence interval (CI) -3.77 to -1.16) and in 2010-2012 (β = -3.64, 95% CI -5.20 to -2.08), and with DBP in 2000-2002 (β = -1.26, 95% CI -2.23 to -0.29) , and 2010-2012 (β = -1.64, 95% CI -2.84 to -0.45) after adjustment for sex, physical activity, and BMI. There was no association between birth weight and the difference in BP between the two periods or the interaction between birth weight, BP, and time interval.

CONCLUSION

Birth weight is a factor associated with BP in adults. This association increased with age, but amplification was shown only with one of the three methods.

Longitudinal growth during fetal life and infancy and cardiovascular outcomes at school-age

OBJECTIVE

Low birth weight is associated with cardiovascular disease. We examined the effects of fetal and infant growth patterns on cardiovascular outcomes in children.

METHODS

In a population-based prospective cohort study among 6239 children, we estimated fetal-femur length and weight by 20 and 30 weeks ultrasound, and child length and weight at birth, 0.5, 1, 2 and 6 years. We measured blood pressure (BP), carotid-femoral pulse wave velocity, aortic root diameter, left ventricular mass and fractional shortening at 6 years. We used regression analyses to identify longitudinal growth patterns associated with height-standardized vascular outcomes and body-surface-area-standardized cardiac outcomes.

RESULTS

Younger gestational age and lower birth weight were associated with higher BP, smaller aortic root diameter and lower left ventricular mass in childhood (all P values <0.05). Children with decelerated or normal fetal growth followed by accelerated infant growth had higher BP, whereas those with decelerated growth during both fetal life and infancy had a relatively larger left ventricular mass. Longitudinal growth analyses showed that children with increased BP tended to be smaller during third trimester of fetal life, but of normal size during infancy, than children with normal BP. Children with increased aortic root diameter or left ventricular mass tended to be larger during fetal life, but of similar size during infancy.

CONCLUSION

Specific fetal and infant growth patterns are associated with different cardiovascular outcomes in children. Further studies are needed to identify the underlying mechanisms and the long-term cardiovascular consequences.

Birth Weight, Postnatal Weight Gain, and Childhood Adiposity in Relation to Lipid Profile and Blood Pressure During Early Adolescence

Background

Different pathways likely underlie the association between early weight gain and cardiovascular disease risk. We examined whether birth weight for length relationship and weight gain up to 2 years of age are associated with lipid profiles and blood pressure (BP) in early adolescence and determined whether childhood adiposity mediates these associations.

Methods and Results

Data from QUALITY (Quebec Adipose and Lifestyle Investigation in Youth), a cohort of white children with parental history of obesity, were analyzed (n=395). Sex‐specific weight for length z scores from birth to 2 years were computed. Rate of postnatal weight gain was estimated using individual slopes of weight for length z‐score measurements. Percentage of body fat was measured at 8 to 10 years. Fasting lipids and BP were measured at 10 to 12 years. Using path analysis, we found indirect effects of postnatal weight gain, through childhood adiposity, on all outcomes: Rate of postnatal weight for length gain was positively associated with childhood adiposity, which in turn was associated with unfavorable lipid and BP levels in early adolescence. In contrast, small beneficial direct effects on diastolic BP z scores, independent of weight at other time points, were found for birth weight for length (β=−0.05, 95% CI, −0.09 to −0.002) and for postnatal weight gain (β=−0.02, 95% CI, −0.03 to −0.002).

Conclusions

Among children with at least 1 obese parent, faster postnatal weight gain leads to cardiovascular risk factors in early adolescence through its effect on childhood adiposity. Although heavier newborns may have lower BP in early adolescence, this protective direct effect could be offset by a deleterious indirect effect linking birth weight to later adiposity.

Longevity is impacted by growth hormone action during early postnatal period

Life-long lack of growth hormone (GH) action can produce remarkable extension of longevity in mice. Here we report that GH treatment limited to a few weeks during development influences the lifespan of long-lived Ames dwarf and normal littermate control mice in a genotype and sex-specific manner. Studies in a separate cohort of Ames dwarf mice show that this short period of the GH exposure during early development produces persistent phenotypic, metabolic and molecular changes that are evident in late adult life. These effects may represent mechanisms responsible for reduced longevity of dwarf mice exposed to GH treatment early in life. Our data suggest that developmental programming of aging importantly contributes to (and perhaps explains) the well documented developmental origins of adult disease.

Endothelial dysfunction in individuals born after fetal growth restriction: cardiovascular and renal consequences and preventive approaches

Individuals born after intrauterine growth restriction (IUGR) have an increased risk of perinatal morbidity/mortality, and those who survive face long-term consequences such as cardiovascular-related diseases, including systemic hypertension, atherosclerosis, coronary heart disease and chronic kidney disease. In addition to the demonstrated long-term effects of decreased nephron endowment and hyperactivity of the hypothalamic-pituitary-adrenal axis, individuals born after IUGR also exhibit early alterations in vascular structure and function, which have been identified as key factors of the development of cardiovascular-related diseases. The endothelium plays a major role in maintaining vascular function and homeostasis. Therefore, it is not surprising that impaired endothelial function can lead to the long-term development of vascular-related diseases. Endothelial dysfunction, particularly impaired endothelium-dependent vasodilation and vascular remodeling, involves decreased nitric oxide (NO) bioavailability, impaired endothelial NO synthase functionality, increased oxidative stress, endothelial progenitor cells dysfunction and accelerated vascular senescence. Preventive approaches such as breastfeeding, supplementation with folate, vitamins, antioxidants, L-citrulline, L-arginine and treatment with NO modulators represent promising strategies for improving endothelial function, mitigating long-term outcomes and possibly preventing IUGR of vascular origin. Moreover, the identification of early biomarkers of endothelial dysfunction, especially epigenetic biomarkers, could allow early screening and follow-up of individuals at risk of developing cardiovascular and renal diseases, thus contributing to the development of preventive and therapeutic strategies to avert the long-term effects of endothelial dysfunction in infants born after IUGR.

Association between high birth weight and hypertension in children and adolescents: a cross-sectional study in China

This study aims to examine the relationship between high birth weight (HBW) and blood pressure and assess whether HBW leads to increased hypertension during childhood and adolescence. All the participants aged 6-18 years with HBW were selected from a cross-sectional study from seven provinces in China. Nine thousand nine hundred and sixty-two children were randomly sampled with matched data. Basic information of students was collected with a standardized student and guardian questionnaire. High blood pressure was defined according to sex-, age- and height-specific references. Multi-variance logistic regression was used to estimate the odds ratio (OR) of high blood pressure and HBW after adjustment for confounding factors. The overall mean of systolic BP and diastolic BP in HBW group were significantly higher than normal group in both genders and urban/rural area. Corresponding overall prevalence of high BP, elevated SBP and elevated DBP in HBW group were also higher than normal group in both genders, respectively (boys: 19.41% vs 16.16%; 10.12% vs 8.16%; 14.86% vs 12.71%; girls: 14.95% vs 12.66%; 8.19% vs 6.56%; 11.13% vs 9.86%). In addition, birth weight was positively associated with high BP, elevated SBP and elevated DBP in children and adolescents of both sexes (boys: OR 1.25, 1.27, 1.20; girls: OR 1.21, 1.27, 1.15). However, the positive association was attenuated and even reversed after adjustment for potential confounding variables. In this study, HBW may lead to higher childhood blood pressure, but no association between HBW and childhood hypertension was observed.

Pubertal testis volume, age at pubertal onset, and adolescent blood pressure: Evidence from Hong Kong's "Children of 1997" birth cohort

OBJECTIVES

A warning from Health Canada suggests that testosterone increases blood pressure (BP). No evidence from large randomized controlled trials is available, and observational studies are confounded by ill-health lowering serum testosterone. To address the evidence gap, we assessed the association of pubertal testicular volume, as a reflection of testosterone production, with BP.

METHODS

We examined whether testicular volume was associated with sex-, age-, and height-standardized BP z-score at ∼13 years in a population-representative Chinese birth cohort (n = 5195, 63% follow-up). We used age at pubertal onset, determined as the earliest age when Tanner stage II for genitalia, breast, or pubic hair, or testicular volume of 4 mL occurred, as control exposures. These exposures were expected to produce findings different from testicular volume because they are not direct measures of testosterone. They were used to ascertain specificity of exposure and to detect residual confounding.

RESULTS

Greater testicular volume was associated with higher systolic BP by 0.03 z-score, which is equivalent to 1.40 mm Hg per standard deviation of testicular volume (95% CI 0.02-0.04), adjusted for infant characteristics, socioeconomic position, and childhood body mass index. Similarly adjusted, earlier pubertal onset was not associated with higher systolic BP z-score in boys or girls.

CONCLUSIONS

Greater pubertal testicular volume is related to higher BP, consistent with a potential role of androgens in the higher BP in boys than girls that emerges during puberty. Our finding provides preliminary evidence supportive of more definitive studies to clarify the warning on testosterone from Health Canada.

Birth size, risk factors across life and cognition in late life: protocol of prospective longitudinal follow-up of the MYNAH (MYsore studies of Natal effects on Ageing and Health) cohort

INTRODUCTION

For late-life neurocognitive disorders, as for other late-life chronic diseases, much recent interest has focused on the possible relevance of Developmental Origins of Health and Disease (DOHaD). Programming by undernutrition in utero, followed by overnutrition in adult life may lead to an increased risk, possibly mediated through cardiovascular and metabolic pathways. This study will specifically examine, if lower birth weight is associated with poorer cognitive functioning in late life in a south Indian population.

METHODS AND ANALYSIS

From 1934 onwards, the birth weight, length and head circumference of all babies born in the CSI Holdsworth Memorial Hospital, Mysore, India, were recorded in obstetric notes. Approximately 800 men and women from the Mysore Birth Records Cohort aged above 55 years, and a reliable informant for each, will be asked to participate in a single cross-sectional baseline assessment for cognitive function, mental health and cardiometabolic disorders. Participants will be assessed for hypertension, type-2 diabetes and coronary heart disease, nutritional status, health behaviours and lifestyles, family living arrangements, economic status, social support and social networks. Additional investigations include blood tests (for diabetes, insulin resistance, dyslipidaemia, anaemia, vitamin B12 and folate deficiency, hyperhomocysteinemia, renal impairment, thyroid disease and Apolipoprotein E genotype), anthropometry, ECG, blood pressure, spirometry and body composition (bioimpedance). We will develop an analysis plan, first using traditional univariate and multivariable analytical paradigms with independent, dependent and mediating/confounding/interacting variables to test the main hypotheses.

ETHICS AND DISSEMINATION

This study has been approved by the research ethics committee of CSI Holdsworth Memorial Hospital. The findings will be disseminated locally and at international meetings, and will be published in open access peer reviewed journals.

Fetal first trimester growth is not associated with kidney outcomes in childhood

BACKGROUND

Impaired fetal growth is associated with increased risks of kidney diseases in later life. Because human development rates are highest during the first trimester, this trimester may be a particularly critical period for kidney outcomes. We have therefore examined the association of fetal first trimester growth with kidney outcomes in childhood.

METHODS

This study was embedded in a prospective population-based cohort study among 1176 pregnant women and their children. We used fetal first trimester crown-length as the growth measure among mothers with a regular menstrual cycle and a known first day of the last menstrual period. At the childhood age of 6 (median 5.7-6.8) years, we measured combined kidney volume, microalbuminuria and estimated glomerular filtration rate (eGFR) based on serum creatinine and cystatin C concentrations.

RESULTS

No consistent associations of fetal first trimester crown-rump length with childhood combined kidney volume, eGFR and microalbuminuria were observed. Compared to children with a fetal first trimester crown-rump length in the highest quintile, those in the lowest quintile had a larger childhood combined kidney volume (difference 5.32 cm³, 95 % confidence interval 1.06 to 9.57), but no differences in kidney function.

CONCLUSION

Our results do not support the hypothesis that fetal first trimester growth restriction affects kidney size and function in childhood. Further studies are needed to focus on critical periods in early life for kidney function and disease in later life.

Critical periods and growth patterns from fetal life onwards associated with childhood insulin levels

AIMS/HYPOTHESIS

We aimed to identify critical periods and specific longitudinal growth patterns from fetal life onwards associated with childhood insulin and C-peptide levels.

METHODS

In a prospective population-based cohort study of 4328 children, we repeatedly measured (femur) length and (estimated fetal) weight from the second trimester of fetal life until 6 years of age. BMI was calculated from 6 months onwards. Insulin and C-peptide levels were measured at 6 years of age.

RESULTS

Preterm birth and small or large size for gestational age at birth were not associated with childhood insulin levels. Conditional growth modelling showed that, independent of growth in other time intervals, weight growth in each time interval from birth onwards, length growth from 6 months onwards and BMI growth from 12 months onwards were positively associated with childhood insulin levels. The strongest associations were present for weight and BMI growth between 48 and 72 months of age. Repeated measurement analyses showed that, compared with children in the lowest quartile of childhood insulin, those in the highest quartile had a higher length from birth onwards and a higher weight and BMI from 24 months onwards. These differences increased with age. No associations were observed for fetal growth characteristics. Similar results were observed for C-peptide levels.

CONCLUSIONS/INTERPRETATION

Our results suggest that rapid length, weight and BMI growth from birth onwards, but not during fetal life, is associated with higher insulin levels in childhood.

Weight Gain and Height Growth during Infancy, Childhood, and Adolescence as Predictors of Adult Cardiovascular Risk

OBJECTIVES

To investigate independent relationships of childhood linear growth (height gain) and relative weight gain to adult cardiovascular disease (CVD) risk traits in Asian Indians.

STUDY DESIGN

Data from 2218 adults from the Vellore Birth Cohort were examined for associations of cross-sectional height and body mass index (BMI) and longitudinal growth (independent conditional measures of height and weight gain) in infancy, childhood, adolescence, and adulthood with adult waist circumference (WC), blood pressure (BP), insulin resistance (homeostatic model assessment-insulin resistance [HOMA-IR]), and plasma glucose and lipid concentrations.

RESULTS

Higher BMI/greater conditional relative weight gain at all ages was associated with higher adult WC, after 3 months with higher adult BP, HOMA-IR, and lipids, and after 15 years with higher glucose concentrations. Taller adult height was associated with higher WC (men β = 2.32 cm per SD, women β = 1.63, both P < .001), BP (men β = 2.10 mm Hg per SD, women β = 1.21, both P ≤ .001), and HOMA-IR (men β = 0.08 log units per SD, women β = 0.12, both P ≤ .05) but lower glucose concentrations (women β = -0.03 log mmol/L per SD P = .003). Greater height or height gain at all earlier ages were associated with higher adult CVD risk traits. These positive associations were attenuated when adjusted for adult BMI and height. Shorter length and lower BMI at birth were associated with higher glucose concentration in women.

CONCLUSIONS

Greater height or weight gain relative to height during childhood or adolescence was associated with a more adverse adult CVD risk marker profile, and this was mostly attributable to larger adult size.

Fetal programming of blood pressure in a transgenic mouse model of altered intrauterine environment

KEY POINTS

Nitric oxide is essential in the vascular adaptation to pregnancy, as knockout mice lacking nitric oxide synthase (NOS3) have abnormal utero-placental perfusion, hypertension and growth restriction. We previously showed with ex vivo studies on transgenic animals lacking NOS3 that adverse intrauterine environment alters fetal programming of vascular reactivity in adult offspring. The current research shows that altered vascular reactivity correlates with higher blood pressure in vivo. Our data suggest that higher blood pressure depends on both genetic background (NOS3 deficiency) and uterine environment, becomes more evident with age (> 7 postnatal weeks), activity and stress, is gender specific (preponderant among males), and can be affected by the sleep-awake cycle. In utero or early postnatal life (< 7 weeks), before onset of hypertension, may represent a potential window for intervention to prevent future cardiovascular disorders.

ABSTRACT

Nitric oxide is involved in the vascular adaptation to pregnancy. Using transgenic animals, we previously showed that adverse intrauterine environment alters vascular reactivity in adult offspring. The aim of our study was to determine if altered vascular programming is associated with abnormal blood pressure (BP) profiles in vivo. Mice lacking a functional endothelial nitric oxide synthase (KO, NOS3-/- ) and wild-type mice (WT, NOS3+/+ ) were crossbred to generate homozygous NOS3-/- (KO), maternally derived heterozygous NOS3+/- (KOM: mother with adverse intrauterine environment from NOS3 deficiency), paternally derived heterozygous NOS3+/- (KOP: mother with normal in utero milieu) and NOS3+/+ (WT) litters. BP was measured in vivo at 7, 14 and 21 weeks of age. After univariate analysis, multivariate population-averaged linear regression models were used to identify factors affecting BP. When compared to WT offspring, systolic (SBP), diastolic (DBP) and mean (MAP) BP progressively increased from KOP, to KOM, and peaked among KO (P < 0.001), although significance was not reached for KOP. Higher BP was also associated with male gender, older age (> 7 postnatal weeks), higher locomotor activity, daytime recordings, and recent blood pressure transducer insertion (P < 0.001). Post hoc analysis showed that KOM had higher SBP than KOP (P < 0.05). Our study indicates that adverse intrauterine environment contributes, along with multiple other factors, to account for hypertension; moreover, in utero or early postnatal life may represent a possible therapeutic window for prevention of cardiovascular disease later in life.

Associations of Maternal and Paternal Blood Pressure Patterns and Hypertensive Disorders during Pregnancy with Childhood Blood Pressure

BACKGROUND

Hypertensive disorders in pregnancy may affect the cardiovascular risk of offspring. We examined the associations of maternal blood pressure throughout pregnancy and hypertensive disorders in pregnancy with childhood blood pressure of offspring. Specific focus was on the comparison with paternal blood pressure effects, the identification of critical periods, and the role of birth outcomes and childhood body mass index in the observed associations.

METHODS AND RESULTS

This study was embedded in a population-based prospective cohort study among 5310 mothers and fathers and their children. We measured maternal blood pressure in each trimester of pregnancy and paternal blood pressure once. Information about hypertensive disorders in pregnancy was obtained from medical records. We measured childhood blood pressure at the median age of 6.0 years (95% range 5.7-8.0 years). Both maternal and paternal blood pressure were positively associated with childhood blood pressure (all P<0.05), with similar effect estimates. Conditional regression analyses showed that early, mid-, and late-pregnancy maternal blood pressure levels were all independent and positively associated with childhood blood pressure, with the strongest effect estimates for early pregnancy. Compared with children of mothers without hypertensive disorders in pregnancy, children of mothers with hypertensive disorders in pregnancy had higher diastolic blood pressure by a standard deviation score of 0.13 (95% CI 0.05-0.21). The observed associations were not materially affected by birth outcomes and childhood body mass index.

CONCLUSIONS

Both maternal and paternal blood pressure affects childhood blood pressure, independent of fetal and childhood growth measures, with the strongest effect of maternal blood pressure in early pregnancy.

Relation of Birth Weight to Heart Rate in Childhood, Adolescence, and Adulthood (from the Bogalusa Heart Study)

Low birth weight is associated with cardiovascular disease and its risk factors in adulthood. However, information is limited regarding its impact on heart rate (HR), an established risk factor for cardiovascular disease. This study assessed the hypothesis that birth weight is associated with HR at rest at different ages. The study sample consisted of 6,282 black and white participants enrolled in the Bogalusa Heart Study, aged 4 to 52 years with a mean age of 19.4 years. HR data at rest were available in 2,344 children (4 to 11 years old), 1,622 adolescents (12 to 19 years old), and 2,316 adults (20 to 52 years old). Birth certificate records, including information on birth weight and gestational age, were obtained from the Louisiana State Office of Public Health. HR showed a significant decreasing trend with increasing age, with blacks having a lower slope than whites. In multivariable linear regression analyses, adjusted for age, race, gender, body mass index, and gestational age, the association between lower birth weight (kg) and increased HR (beats/min) was significant in adults (regression coefficient, β = -1.21, p = 0.006) but not significant in children (β = -0.31, p = 0.461) and adolescents (β = -0.72, p = 0.157). The association did not differ significantly between races. The birth weight-HR association did not change markedly in the models without adjustment for body mass index. In conclusion, these results suggest that the association of prenatal growth retardation with increased cardiovascular disease risk in later life might be partly through its relation with HR at rest.

Relationship between maternal nutrient intakes in early and late pregnancy and infants weight and proportions at birth: prospective cohort study

Experimental studies indicate that fetal undernutrition programmes life-long physiology and disease risk. The objective of this study was to investigate relationships between maternal nutrient intakes in early and late pregnancy with birth weights, placental weights, and infant proportions at birth. A prospective cohort study set in a district general hospital in the east midlands of England considered the diets of 300 pregnant women recruited from an antenatal ultrasound dating scan clinic. Estimation of nutrient intakes utilised five-day food diaries in the first and third trimesters of pregnancy. Two hundred and four diaries were returned and analysed for trimester one and 176 for trimester three. Birth weight and infant head circumference at birth were unrelated to nutrient intakes in the first or third trimester of pregnancy. Placental weight was not related to any maternal nutrient intakes. Thinness at birth was associated with low contributions of carbohydrate to dietary energy (p=0.036). The present study shows that maternal nutrition in well-nourished populations does not exert a strong influence upon fetal growth. These data suggest that reported associations between low weight, thinness or greater head circumference at birth and disease in later life are not attributable to the effects of maternal undernutrition.

Performance of targeted screening for the identification of hypertension in children

Targeted screening of hypertension in childhood might be more efficient than universal screening. We estimated the sensitivity, specificity, negative and positive predictive values of combined parental history of hypertension and overweight/obesity for the diagnosis of hypertension in 5207 children aged 10-14 years. Children had hypertension if they had sustained elevated blood pressure over three separate visits. The prevalence of hypertension was 2.2%. 14% of children were overweight or obese, 20% had a positive history of hypertension in at least one parent and 30% had either or both conditions. Targeted screening of hypertension to children with either overweight/obesity or with hypertensive parents limits the proportion of children (30%) to screen and identifies up to 65% of all hypertensive cases.

Joint modelling compared with two stage methods for analysing longitudinal data and prospective outcomes: A simulation study of childhood growth and BP

There is a growing debate with regards to the appropriate methods of analysis of growth trajectories and their association with prospective dependent outcomes. Using the example of childhood growth and adult BP, we conducted an extensive simulation study to explore four two-stage and two joint modelling methods, and compared their bias and coverage in estimation of the (unconditional) association between birth length and later BP, and the association between growth rate and later BP (conditional on birth length). We show that the two-stage method of using multilevel models to estimate growth parameters and relating these to outcome gives unbiased estimates of the conditional associations between growth and outcome. Using simulations, we demonstrate that the simple methods resulted in bias in the presence of measurement error, as did the two-stage multilevel method when looking at the total (unconditional) association of birth length with outcome. The two joint modelling methods gave unbiased results, but using the re-inflated residuals led to undercoverage of the confidence intervals. We conclude that either joint modelling or the simpler two-stage multilevel approach can be used to estimate conditional associations between growth and later outcomes, but that only joint modelling is unbiased with nominal coverage for unconditional associations.

Intrauterine growth restriction: impact on cardiovascular development and function throughout infancy

Intrauterine growth restriction (IUGR) refers to the situation where a fetus does not grow according to its genetic growth potential. One of the main causes of IUGR is uteroplacental vascular insufficiency. Under these circumstances of chronic oxygen and nutrient deprivation, the growth-restricted fetus often displays typical circulatory changes, which in part represent adaptations to the suboptimal intrauterine environment. These fetal adaptations aim to preserve oxygen and nutrient supply to vital organs such as the brain, the heart, and the adrenals. These prenatal circulatory adaptations are thought to lead to an altered development of the cardiovascular system and "program" the fetus for life long cardiovascular morbidities. In this review, we discuss the alterations to cardiovascular structure, function, and control that have been observed in growth-restricted fetuses, neonates, and infants following uteroplacental vascular insufficiency. We also discuss the current knowledge on early life surveillance and interventions to prevent progression into chronic disease.

Gender differences in developmental programming of cardiovascular diseases

Hypertension is a risk factor for cardiovascular disease, the leading cause of death worldwide. Although multiple factors contribute to the pathogenesis of hypertension, studies by Dr David Barker reporting an inverse relationship between birth weight and blood pressure led to the hypothesis that slow growth during fetal life increased blood pressure and the risk for cardiovascular disease in later life. It is now recognized that growth during infancy and childhood, in addition to exposure to adverse influences during fetal life, contributes to the developmental programming of increased cardiovascular risk. Numerous epidemiological studies support the link between influences during early life and later cardiovascular health; experimental models provide proof of principle and indicate that numerous mechanisms contribute to the developmental origins of chronic disease. Sex has an impact on the severity of cardiovascular risk in experimental models of developmental insult. Yet, few studies examine the influence of sex on blood pressure and cardiovascular health in low-birth weight men and women. Fewer still assess the impact of ageing on sex differences in programmed cardiovascular risk. Thus, the aim of the present review is to highlight current data about sex differences in the developmental programming of blood pressure and cardiovascular disease.

Chronic Blockade of the Androgen Receptor Abolishes Age-Dependent Increases in Blood Pressure in Female Growth-Restricted Rats

Intrauterine growth restriction induced via placental insufficiency programs a significant increase in blood pressure at 12 months of age in female growth-restricted rats that is associated with early cessation of estrous cyclicity, indicative of premature reproductive senescence. In addition, female growth-restricted rats at 12 months of age exhibit a significant increase in circulating testosterone with no change in circulating estradiol. Testosterone is positively associated with blood pressure after menopause in women. Thus, we tested the hypothesis that androgen receptor blockade would abolish the significant increase in blood pressure that develops with age in female growth-restricted rats. Mean arterial pressure was measured in animals pretreated with and without the androgen receptor antagonist, flutamide (8 mg/kg/day, SC for 2 weeks). Flutamide abolished the significant increase in blood pressure in growth-restricted rats relative to control at 12 months of age. To examine the mechanism(s) by which androgens contribute to increased blood pressure in growth-restricted rats, blood pressure was assessed in rats untreated or treated with enalapril (250 mg/L for 2 weeks). Enalapril eliminated the increase in blood pressure in growth-restricted relative to vehicle- and flutamide-treated controls. Furthermore, the increase in medullary angiotensin type 1 receptor mRNA expression was abolished in flutamide-treated growth-restricted relative to untreated counterparts and controls; cortical angiotensin-converting enzyme mRNA expression was reduced in flutamide-treated growth-restricted versus untreated counterparts. Thus, these data indicate that androgens, via activation of the renin-angiotensin system, are important mediators of increased blood pressure that develops by 12 months of age in female growth-restricted rats.

Birth Weight, Birth Length, and Gestational Age as Indicators of Favorable Fetal Growth Conditions in a US Sample

The "fetal origins" hypothesis suggests that fetal conditions not only affect birth characteristics such as birth weight and gestational age, but also have lifelong health implications. Despite widespread interest in this hypothesis, few methodological advances have been proposed to improve the measurement and modeling of fetal conditions. A Statistics in Medicine paper by Bollen, Noble, and Adair examined favorable fetal growth conditions (FFGC) as a latent variable. Their study of Filipino children from Cebu provided evidence consistent with treating FFGC as a latent variable that largely mediates the effects of mother's characteristics on birth weight, birth length, and gestational age. This innovative method may have widespread utility, but only if the model applies equally well across diverse settings. Our study assesses whether the FFGC model of Cebu replicates and generalizes to a very different population of children from North Carolina (N=705) and Pennsylvania (N=494). Using a series of structural equation models, we find that key features of the Cebu analysis replicate and generalize while we also highlight differences between these studies. Our results support treating fetal conditions as a latent variable when researchers test the fetal origins hypothesis. In addition to contributing to the substantive literature on measuring fetal conditions, we also discuss the meaning and challenges involved in replicating prior research.

Associations between adiposity, hormones, and gains in height, whole-body height-adjusted bone size, and size-adjusted bone mineral content in 8- to 11-year-old children

We examined fat-independent associations of hormones with height and whole-body bone size and mineral content in 633 school children. IGF-1 and osteocalcin predict growth in height, while fat, osteocalcin, and in girls also, IGF-1 predict growth in bone size. Leptin and ghrelin are inversely associated with bone size in girls.

INTRODUCTION

Obesity causes larger bone size and bone mass, but the role of hormones in this up-regulation of bone in obesity is not well elucidated. We examined longitudinal associations between baseline body fat mass (FM), and fat-independent fasting levels of ghrelin, adiponectin, leptin, insulin, insulin-like growth factor-I (IGF-1), osteocalcin, and intact parathyroid hormone, and subsequent changes in height and in whole-body height-adjusted bone area "BAheight" and size-adjusted bone mineral content "BMCsize" in 8- to 11-year-olds.

METHODS

Analyses were carried out separately for boys (n = 325) and girls (n = 308) including data from baseline, 3 and 6 months from OPUS School Meal Study.

RESULTS

In both sexes: gain in BAheight was positively associated with baseline FM (≥2.05 cm(2)/kg, both p ≤ 0.003). Furthermore, gain in height was positively associated with baseline IGF-1 (≥0.02 cm/ng/ml, p = 0.001) and osteocalcin (≥0.13 cm/ng/ml, p ≤ 0.009); and gain in BAheight was positively associated with baseline osteocalcin (≥0.35 cm(2)/ng/ml, p ≤ 0.019). In girls only, gain in BAheight was also positively associated with baseline IGF-1 (0.06 cm(2)/ng/ml, p = 0.017) and inversely associated with both baseline ghrelin (-0.01 cm(2)/pg/ml, p = 0.001) and leptin (-1.21 cm(2)/μg/ml, p = 0.005). In boys, gain in BMCsize was positively associated with osteocalcin (0.18 g/ng/ml, p = 0.030).

CONCLUSIONS

This large longitudinal study suggests that in 8- to 11-year-old children, IGF-1 and osteocalcin predict growth in height, while FM, osteocalcin, and in girls also, IGF-1 predict growth in BAheight. Fat-independent inverse associations of leptin and ghrelin with BAheight in girls' are contrary to proposed growth-stimulating effects of leptin. Osteocalcin in boys predicts gain in BMCsize.

Birth weight and adult cardiovascular risk factors using multiple birth status as an instrumental variable in the 1958 British Birth Cohort

BACKGROUND

Birth weight is classified as a risk factor for cardiovascular disease by the World Health Organization, but appropriate preventive interventions remain unclear because the observations have not been confirmed in experiments and appear to be contextually specific.

METHODS

Using 9452 participants of the 1958 British Birth Cohort at age 42years in 2000 (58% follow-up), we examined the credibility of multiple birth status as an instrumental variable (IV) for birth weight and, if appropriate, use it to obtain less confounded estimates of the associations of birth weight with cardiovascular disease risk factors including self-reported height, body mass index and hypertension than conventional regression in 2014.

RESULTS

Multiple birth (203 twins and 6 triplets) was associated with older maternal age, but not with paternal occupation or maternal smoking. Multiple births had lower birth weight-for-gestational age z-score. Multiple birth status was not directly associated with height, BMI or hypertension. Using IV estimates birth weight-for-gestational age z-score was not clearly associated with height (0.99cm, 95% confidence interval (CI) -0.27, 2.25), body mass index (BMI) (0.42kg/m(2), 95% CI -0.17, 1.01) or hypertension (risk ratio 0.82, 95% CI 0.54, 1.23) adjusted for maternal age, with a first-stage F statistic of 145.3 from IV analysis.

CONCLUSIONS

Multiple birth status is a credible IV for obtaining a less confounded estimate of the association of birth weight with height, BMI and blood pressure. Such analysis suggests that birth weight may be spuriously related to height, BMI and blood pressure, and thus not an effective target for intervention.

Heterogeneity identified at birth and blood pressure in adulthood

OBJECTIVE

In the developmental programming literature, the association of birth weight and blood pressure later in life is modest at best. This article reexamines this issue using Covariate Density Defined mixture of regressions (CDDmr) to determine if a latent variable, based on birth weight, and known to influence infant mortality, provides a stronger indicator of developmental programming.

METHODS

CDDmr identifies two latent components in the birth weight distribution, generally interpreted in the infant mortality literature as "compromised" and "normal" fetal development. The data are taken from the 1958 British National Child Development Study.

RESULTS

In the 1958 cohort, the "compromised" component consists of about 10% of the birth weight distribution. Compared to "normal" births, the mean systolic blood pressure at age 45 of "compromised" births is 20.3 (females) and 26.4 (males) mm Hg higher than "normal" births. The relative risks of stage-I-II systolic hypertension (>140 mm Hg) of "compromised" births compared to "normal" births are 10.7 (females) and 4.2 (males). The relative risks of stage-II systolic hypertension (>160 mm Hg) are considerably higher, 241.6 (females) and 74.3 (males). In general, the highest blood pressures are observed in "compromised" births with birth weights within the normal (about 3.0-3.5 kg) birth weight range. Results for diastolic blood pressure are similar.

CONCLUSIONS

These associations are much stronger than those identified using conventional methods. CDDmr is likely to be useful for studying the dynamics of developmental programming particularly in large cohort studies where birth weight is often the only indicator of programming available. Am. J. Hum. Biol. 28:545-554, 2016. © 2016 Wiley Periodicals, Inc.

Familial Factors, Low Birth Weight, and Development of ESRD: A Nationwide Registry Study

BACKGROUND

Previous studies have demonstrated that low birth weight (LBW) is associated with higher risk for end-stage renal disease (ESRD). However, both LBW and ESRD cluster in families. The present study investigates whether familial factors explain the association between LBW and ESRD.

STUDY DESIGN

Retrospective registry-based cohort study.

SETTING & PARTICIPANTS

Since 1967, the Medical Birth Registry of Norway has recorded medical data for all births in the country. Sibling data are available through the Norwegian Population Registry. Since 1980, all patients with ESRD in Norway have been registered in the Norwegian Renal Registry. Individuals registered in the Medical Birth Registry with at least 1 registered sibling were included.

PREDICTOR

LBW in the participant and/or LBW in at least 1 sibling.

OUTCOME

ESRD.

RESULTS

Of 1,852,080 included individuals, 527 developed ESRD. Compared with individuals without LBW and with no siblings with LBW, individuals without LBW but with a sibling with LBW had an HR for ESRD of 1.20 (95% CI, 0.91-1.59), individuals with LBW but no siblings with LBW had an HR of 1.59 (95% CI, 1.18-2.14), and individuals with LBW and a sibling with LBW had an HR of 1.78 (95% CI, 1.26-2.53). Similar results were observed for individuals who were small for gestational age (SGA). Separate analyses for the association of age 18 to 42 years and noncongenital ESRD showed stronger associations for SGA than for LBW, and the associations were not statistically significant for age 18 to 42 years for LBW.

LIMITATIONS

Follow-up only until 42 years of age.

CONCLUSIONS

LBW and SGA are associated with higher risk for ESRD during the first 40 years of life, and the associations were not explained by familial factors. Our results support the hypothesis that impaired intrauterine nephron development may be a causal risk factor for progressive kidney disease.

Low Birth Weight as a Predictor of Cardiovascular Risk Factors in Childhood and Adolescence? The PEP Family Heart Study

BACKGROUND

Low birth weight is considered a risk factor for cardiovascular disease (CVD) in later life. Because data in children and adolescents are sparse and controversial, we assessed the association of birth weight with CVD risk factors in German youths.

METHODS

We categorized 843 urban children and adolescents aged 3-18 years by quintiles of birth weight and measured nine traditional risk factors in terms of body mass index (BMI), waist circumference (WC), systolic (SBP) and diastolic (DBP) blood pressure, total cholesterol (TC), LDL-C, HDL-C, Non HDL-C and triglycerides (TG). SPSS 21 was used for statistical analysis.

RESULTS

Mean values and prevalence of nine anthropometric and lipid risk variables were equally distributed over the five birth weight groups. Though risk factors clustered between 3.0 kg and 4.0 kg of birth weight in both genders we found only one significant correlation of birth weight with TG for males and females and another one for HDL-C in males. The strongest clustering of significant regression coefficients occurred in the 2(nd) birth weight quintile for SBP (ß 0.018), TC (ß -0.050), LDL-C (ß -0.039), non LDL-C (ß -0.049) and log TG (ß -0.001) in males and females.

CONCLUSIONS

Overall we did not find significant associations between birth weight and nine traditional cardiovascular risk factors in children and adolescents. However, the 2(nd) quintile of birth weight might suggest clustering of risk factors.

Perinatal inflammation: a common factor in the early origins of cardiovascular disease?

Cardiovascular disease continues to be the leading cause of global morbidity and mortality. Traditional risk factors account for only part of the attributable risk. The origins of atherosclerosis are in early life, a potential albeit largely unrecognized window of opportunity for early detection and treatment of subclinical cardiovascular disease. There are robust epidemiological data indicating that poor intrauterine growth and/or prematurity, and perinatal factors such as maternal hypercholesterolaemia, smoking, diabetes and obesity, are associated with adverse cardiovascular intermediate phenotypes in childhood and adulthood. Many of these early-life risk factors result in a heightened inflammatory state. Inflammation is a central mechanism in the development of atherosclerosis and cardiovascular disease, but few studies have investigated the role of overt perinatal infection and inflammation (chorioamnionitis) as a potential contributor to cardiovascular risk. Limited evidence from human and experimental models suggests an association between chorioamnionitis and cardiac and vascular dysfunction. Early life inflammatory events may be an important mechanism in the early development of cardiovascular risk and may provide insights into the associations between perinatal factors and adult cardiovascular disease. This review aims to summarise current data on the early life origins of atherosclerosis and cardiovascular disease, with particular focus on perinatal inflammation.

Childhood to Early-Midlife Systolic Blood Pressure Trajectories: Early-Life Predictors, Effect Modifiers, and Adult Cardiovascular Outcomes

Previous studies examining blood pressure change over time have modeled an average population trajectory. Recent research among older adults suggests there may be subgroups with different blood pressure trajectories. Identifying subgroups at risk of developing adult hypertension early in life can inform effective risk reduction efforts. We sought to identify different systolic blood pressure trajectories from childhood, their correlated risk factors, and early-midlife cardiovascular outcomes. Blood pressure data at ages 7, 11, 18, 26, 32, and 38 years from a longitudinal, representative birth cohort study (n=975) were used to identify 4 distinct trajectory groups via group-based trajectory modeling: normal (21.8%), high-normal (43.3%), prehypertensive (31.6%), and hypertensive (4.2%). The categories refer to blood pressure beginning at the age of 7 years and most recently measured at the age of 38 years. Family history of high blood pressure (odds ratio [OR], 43.23; 95% confidence interval [CI], 5.27-354.65), male sex (OR, 109.48; 95% CI, 26.82-446.96), being first born (OR, 2.5; 95% CI, 1.00-8.69) and low birth weight (OR, 2.79; 95% CI, 2.49-3.09) were associated with hypertensive group membership (compared with the normal group). Higher body mass index and cigarette smoking resulted in increasing blood pressure across trajectories, particularly for the higher blood pressure groups. Prehypertensive and hypertensive trajectory groups had worse cardiovascular outcomes by early midlife. Harmful blood pressure trajectories are identifiable in childhood, associated with both antecedent and modifiable risk factors over time, and predict adult cardiovascular disease risk. Early detection and subsequent targeted prevention and intervention may reduce the lifecourse burden associated with higher blood pressure.

Programming of Essential Hypertension: What Pediatric Cardiologists Need to Know

Hypertension is recognized as one of the major contributing factors to cardiovascular disease, but its etiology remains incompletely understood. Known genetic and environmental influences can only explain a small part of the variability in cardiovascular disease risk. The missing heritability is currently one of the most important challenges in blood pressure and hypertension genetics. Recently, some promising approaches have emerged that move beyond the DNA sequence and focus on identification of blood pressure genes regulated by epigenetic mechanisms such as DNA methylation, histone modification and microRNAs. This review summarizes information on gene-environmental interactions that lead toward the developmental programming of hypertension with specific reference to epigenetics and provides pediatricians and pediatric cardiologists with a more complete understanding of its pathogenesis.

A life course approach to cardiovascular aging

A life course approach in epidemiology investigates the biological, behavioral and social pathways that link physical and social exposures and experiences during gestation, childhood, adolescence and adult life, and across generations, to later-life health and disease risk. We illustrate how a life course approach has been applied to cardiovascular disease, highlighting the evidence in support of the early origins of disease risk. We summarize how trajectories of cardiometabolic risk factors change over the life course and suggest that understanding underlying 'normal' or 'healthy' trajectories and the characteristics that drive deviations from such trajectories offer the potential for early prevention and for identifying means of preventing future disease.

Associations between early body mass index trajectories and later metabolic risk factors in European children: the IDEFICS study

Faster growth seems to be a common factor in several hypotheses relating early life exposures to subsequent health. This study aims to investigate the association between body mass index (BMI) trajectories during infancy/childhood and later metabolic risk in order to identify sensitive periods of growth affecting health. In a first step, BMI trajectories of 3301 European children that participated in the multi-centre Identification and Prevention of Dietary and Lifestyle-induced Health Effects in Children and Infants (IDEFICS) study were modelled using linear-spline mixed-effects models. The estimated random coefficients indicating initial subject-specific BMI and rates of change in BMI over time were used as exposure variables in a second step and related to a metabolic syndrome (MetS) score and its single components based on conditional regression models (mean age at outcome assessment: 8.5 years). All exposures under investigation, i.e. BMI at birth, rates of BMI change during infancy (0 to <9 months), early childhood (9 months to <6 years) and later childhood (≥6 years) as well as current BMI z-score were significantly associated with the later MetS score. Associations were strongest for the rate of BMI change in early childhood (1.78 [1.66; 1.90]; β estimate and 99 % confidence interval) and current BMI z-score (1.16 [0.96; 1.38]) and less pronounced for BMI at birth (0.62 [0.47; 0.78]). Results slightly differed with regard to the single metabolic factors. Starting from birth rapid BMI growth, especially in the time window of 9 months to <6 years, is significantly related to later metabolic risk in children. Much of the associations of early BMI growth may further be mediated through the effects on subsequent BMI growth.

Joint association between birth weight at term and later life adherence to a healthy lifestyle with risk of hypertension: a prospective cohort study

BACKGROUND

Low birth weight and unhealthy lifestyles in adulthood have been independently associated with an elevated risk of hypertension. However, no study has examined the joint effects of these factors on incidence of hypertension.

METHODS

We followed 52,114 women from the Nurses' Health Study II without hypercholesterolemia, diabetes, cardiovascular disease, cancer, prehypertension, and hypertension at baseline (1991-2011). Women born preterm, of a multiple pregnancy, or who were missing birth weight data were excluded. Unhealthy adulthood lifestyle was defined by compiling status scores of body mass index, physical activity, alcohol consumption, the Dietary Approaches to Stop Hypertension diet, and the use of non-narcotic analgesics.

RESULTS

We documented 12,588 incident cases of hypertension during 20 years of follow-up. The risk of hypertension associated with a combination of low birth weight at term and unhealthy lifestyle factors (RR, 1.95; 95 % CI, 1.83-2.07) was more than the addition of the risk associated with each individual factor, indicating a significant interaction on an additive scale (P interaction <0.001). The proportions of the association attributable to lower term birth weight alone, unhealthy lifestyle alone, and their joint effect were 23.9 % (95 % CI, 16.6-31.2), 63.7 % (95 % CI, 60.4-66.9), and 12.5 % (95 % CI, 9.87-15.0), respectively. The population-attributable-risk for the combined adulthood unhealthy lifestyle and low birth weight at term was 66.3 % (95 % CI, 56.9-74.0).

CONCLUSION

The majority of cases of hypertension could be prevented by the adoption of a healthier lifestyle, though some cases may depend on simultaneous improvement of both prenatal and postnatal factors.