Body size at birth and blood pressure among children in developing countries

Barker Hypothesis and Hypertension

Early onset hypertension is one of many major medical disorders that have evolved over the current millennium across both the developing as well as the developed world. Though various mechanisms have been postulated for the evolution of hypertension in these individuals, one of the most relevant ones is that of low birth weight and its association with hypertension. Barker from historical evidence has postulated the foetal onset adult disease (FOAD) or Thrifty phenotype on Low Birth Weight (LBW) associated hypertension. Later, Brenner highlighted the importance of low nephron mass and future implications. In this review we elaborate the mechanisms that were postulated for LBW-related hypertension as well the potential antihypertensive therapy that may be used in these individuals.

Birth weight is inversely correlated with blood pressure: population-based study

BACKGROUND AND METHOD

The current representative national cross-sectional study examines the association of birth weight and blood pressure (BP) among the adult Australian population.Questions about birth weight were added to the second round of AusDiab study. Hypertension was defined based on WHO (≥140/90), and NCEP-ATPIII (≥130/85). Both definitions were examined against the continuous birth weight and dichotomous variable of low birth weight (LBW); less than 2.5 kg, adjusting for age, BMI, physical activity, smoking, alcohol intake and socioeconomic factors.

RESULTS

A total of 4502 respondents reported their birth weights with a mean (SD) of 3.37 (0.7) kg. Females with LBW had significantly higher mean SBP and DBP than those with normal birth weight. This relationship persisted with adjustments for various confounding factors. Males with LBW showed a trend towards a higher SBP and DBP, though NS, than normal birth weight more than 2.5 kg. LBW individuals, less than 2.5 kg were at higher risk for having high SBP hypertension at least 140/90 mmHg and at least 130/85 mmHg compared with those with normal birth weight. Among females, for each kilogramme of birth weight, there was a predicted decrease of 1.59 (0.7, 2.5) mmHg in SBP, P = 0.001 and 0.85 (0.2, 1.5) mmHg in DBP, P = 0.001; after adjustments for age, body size, physical activity, smoking status, alcohol intake and socioeconomic factors. Among males, for each kilogramme of birth weight, there was a decrease of 1.74 (0.7, 2.8) mmHg in SBP, P = 0.002 and 1.06 (0.3, 1.9) mmHg in DBP, P = 0.008 after adjustments for all confounding factor.

CONCLUSION

This study has examined the association of birth weight and BP in a representative adult population. LBW was significantly associated with the risk of developing high BP.

Anthropometric measurements of singleton live full-term newborns in Aden, Yemen

BACKGROUND

Neonatal anthropometry is the single most portable, universally applicable cheap, and non-invasive technique that deals with a variety of human body measurements. The anthropometric data for newborns, infants and children reflect their general health, nutritional status, and future survival by tracking trends in growth and development over time.

PATIENTS AND METHODS

The present study was conducted on 1000 Yemeni singleton live full-term newborns (37-42 weeks gestation), 488 males and 512 females during first 24 h of delivery at Al-Sadaqa Teaching Hospital, Aden, Yemen during the years 2002-2003.

RESULTS

The data analysis of seven anthropometric values for 1000 Yemeni term newborns of both sexes revealed the mean birth weight and SD was 3113.04 g (±519.52), crown-heel length, head, chest, mid-arm, abdominal and calf circumferences were 48.91 (1.62), 33.78 (1.13), 32.09 (1.48), 10.09 (1.02), 30.10 (1.92), and 10.94 (1.04) respectively. The Ponderal Index was calculated with mean value of 2.65 (0.40). This study showed significant sex differences in all the anthropometric measurements principally in the birth weight (3187.66 versus 3039.04) and crown-heel length CHL (49.28 versus 48.53). (P < .001). The best cut-off point to determine LBW was calf circumference (8.5 cm), which showed the most significant correlation with birth weight (r = 0.5) followed by chest (r = 0.44) and mid-arm circumference (r = 0.41).

CONCLUSIONS

This study of normal reference values will provide basic step for future standardization of Yemen anthropometric parameters to be used for accurate assessment, development and maturity of newborn births that would lead to identify newborns at risk and help in better management.

Is small placenta a risk for low birth weight in KOKAN? (Data from a coastal region in the state of Maharashtra, India)

KOKAN region is characterized by undernutrition across all stages of lifecycle. Developmental Origins of Health & Disease hypothesis suggests that environmental influences in the early period of growth and development can contribute to the risks of noncommunicable diseases (NCD) in adulthood. Newborns and placentas of 815 pregnant mothers delivered in a rural hospital were studied. We tested the hypothesis that low placental weight will be associated with low birth weight (LBW). Mothers had a mean age of 26 years and were smaller in size at delivery [mean height of 152.1 cm (±6.1 cm), weight 52 kg (±10.2 kg), body mass index (BMI) 22.5 kg/m2 (±4.1 kg/m2)]. Mean placental weight was 488 g (±120 g). Mean birth weight, length, and head circumference of the newborn were 2.54 kg (±0.5 kg), 46.3 cm (±3.1 cm), and 32.7 cm (±1.7 cm), respectively. Prevalence of LBW, stunting, and small head size was 41.6%, 42.2%, and 18.2%, respectively. Maternal height, weight, and BMI at delivery were all positively associated with placental weight (p < 0.01 for all). Mothers with placentas in the lowest placental weight tertile had an increased likelihood of producing an LBW baby [OR 7.7, 95% CI (5.0, 11.8)], a stunted baby [OR 1.9 (1.4, 2.9)], or a baby with a small head circumference [OR 2.4 (1.4, 4.0)]. Mothers in the lowest height tertile had odds of producing a LBW baby [OR 1.8 95% CI (1.2, 2.7)] or a stunted baby [OR 1.6 (1.1, 2.3)]. There is a need to improve the nutritional status of women in KOKAN region which may reduce the risk of NCD.

Hypertension in Developing Countries: A Major Challenge for the Future

PURPOSE OF REVIEW

Outline recent epidemiologic data regarding hypertension in developing countries, distinguish differences from developed countries, and identify challenges in management and future perspectives.

RECENT FINDINGS

Increased sugar intake, air and noise pollution, and low birth weight are emerging hypertension risk factors. The major challenges in management are difficulties in accurate diagnosis of hypertension and adequate blood pressure control. In contrast to developed countries, hypertension prevalence rates are on the rise in developing countries with no improvement in awareness or control rates. The increasing burden of hypertension is largely attributable to behavioral factors, urbanization, unhealthy diet, obesity, social stress, and inactivity. Health authorities, medical societies, and drug industry can collaborate to improve hypertension control through education programs, public awareness campaigns, legislation to limit salt intake, encourage generic drugs, development and dissemination of national guidelines, and involving nurses and pharmacists in hypertension management. More epidemiologic data are needed in the future to identify reasons behind increased prevalence and poor blood pressure control and examine trends in prevalence, awareness, treatment, and control. National programs for better hypertension control based on local culture, economic characteristics, and available resources in the population are needed. The role of new tools for hypertension management should be tested in developing world.

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.

Risk of low birth weight on adulthood hypertension - evidence from a tertiary care hospital in a South Asian country, Sri Lanka: a retrospective cohort study

BACKGROUND

Although low birth weight (LBW) is common in South Asian region there are not many studies being done to evaluate LBW and adulthood hypertension association in this region, including in Sri Lanka. Although this association has been studied in other regions, most studies have not evaluated this association in the presence of socioeconomic and lifestyle factors. This study was conducted to investigate whether low birth weight (LBW) is associated with adulthood hypertension after adjusting for other potential risk factors of hypertension.

METHODS

Nearly 15,000 individuals born during 1950 to 1965 were selected and invitations were sent to their original addresses. Out of them 217 individuals responded and among them birth weight was recovered for 122 individuals. Separate linear logistic models were fitted to model high systolic blood pressure (SBP: systolic blood pressure > 140 mmHg), high diastolic blood pressure (DBP: diastolic blood pressure > 90 mmHg) and hypertension (either SBP > 140 mmHg or DBP > 90 mmHg).

RESULTS

Separate linear logistic model fitting revealed LBW having a significant association with high SBP (OR = 2.89; 95% CI: 1.01 to 8.25; P = 0.04), and hypertension (OR = 3.15; 95% CI: 1.17 to 9.35; P = 0.03), but not with high DBP (OR = 0.75; 95% CI: 0.22 to 2.16; P = 0.62), when effect of LBW was studied after adjusting for all other potential risk factors.

CONCLUSIONS

LBW has a tendency to cause high adult blood pressure in South Asian region, and the findings are consistent with previous work on LBW and adulthood hypertension association in other regions of the world.

Inadequate gestational weight gain increases risk of small-for-gestational-age term birth in girls in Japan: A population-based cohort study

OBJECTIVES

Babies born small for gestational age (SGA) have a higher risk of neonatal morbidity and mortality as well as later life chronic disease. The objectives of this study were to examine the extent to which prepregnancy body mass index (BMI) and gestational weight gain (GWG) influenced risk of SGA among Japanese, and to evaluate physician response to, and potential effects on, GWG.

METHODS

We examined SGA risk as a function of maternal BMI and GWG using logistic regression with data from maternal child health handbooks obtained from women in Japan (N = 383). Physicians' written comments on weight and dietary restriction were analyzed for responses to and influence on GWG.

RESULTS

SGA babies comprised 8.6% of the sample, with 13% and 6% of the mothers being underweight and overweight, respectively, and 21.7% and 19.8% of mothers gaining less and more than the recommended amounts, respectively. In adjusted models, higher prepregnancy BMI and GWG were associated with lower risk of SGA (OR 0.71, 95% CI 0.56, 0.90; 0.75, 95% CI 0.61, 0.92 respectively) in models for girls, but not for boys. Inadequate GWG was associated with higher risk of SGA in girls (OR 6.64, 95% CI 2.18, 20.22). Physician written instructions to restrict dietary intake and weight gain followed an average weight gain of 0.69 kg/week from the previous prenatal exam, and were followed by weight gains that decreased to 0.30 kg/week.

CONCLUSIONS

Prepregnancy BMI and GWG significantly influence SGA risk in female babies. GWG may be influenced by physicians' recommendations. Am. J. Hum. Biol. 28:714-720, 2016. © 2016 Wiley Periodicals, Inc.

Strengths and limitations of current pediatric blood pressure nomograms: a global overview with a special emphasis on regional differences in neonates and infants

The availability of robust nomograms is essential for the correct evaluation of blood pressure (BP) values in children. A literature search was conducted by accessing the National Library of Medicine by using the keywords BP, pediatric and reference values/nomograms. A total of 43 studies that evaluated pediatric BP nomograms were included in this review. Despite the accuracy of the latest studies, many numerical and methodological limitations still remain. The numerical limitations include the paucity of data for neonates/infants and for some geographic areas (Africa/South America/East Europe/Asia) and ethnicities. Furthermore, the data on ambulatory BP and response to exercise are extremely limited, and the criteria for stress-test interruption are lacking. There was heterogeneity in the methodologies employed to perform the measurements, in the inclusion/exclusion criteria (often not reported), in the data normalization and the data expression (Z-scores/percentiles/mean values). Although most studies adjusted the measurements for age and/or height, the classification by specific age/height subgroups varied. Gender differences were generally considered, whereas other confounders (that is, ethnicity/geographic area/environment) were seldom evaluated. As a result, nomograms were heterogeneous, and when comparable, at times showed widely different confidence intervals. These differences are most likely because of both methodological limitations and differences among the populations studied. Some robust nomograms exist (particularly those from the USA); however, it has been demonstrated that if adopted in other countries/continents, they may generate an unpredictable bias in the evaluation of BP values in children. Actual pediatric BP nomograms present consistent limitations that affect the evaluation of BP in children. Comprehensive nomograms, which are based on a large population of healthy children (including neonates/infants) and use standardized methodology, are warranted for every country/region.

Intra-uterine growth restriction as a risk factor for hypertension in children six to 10 years old

Introduction

Intra-uterine growth restriction (IUGR) is present in about 3–10% of live-born newborns and it is as high as 20–30% in developing countries. Since the 1990s, it has been known that abnormalities during foetal growth may result in cardiovascular disease, including hypertension in adulthood.

Methods

This study evaluated blood pressure parameters (using ambulatory blood pressure monitoring) in children aged six to 10 years old, born as small for gestational age (SGA), and compared them to their healthy peers born as appropriate for gestational age (AGA).

Results

In the SGA group, an abnormal blood pressure level (prehypertension or hypertension) was present significantly more often than in the AGA group (50 vs 16%, p < 0.01). This relationship also occurred in association with the type of IUGR (asymmetric p < 0.01, symmetric p < 0.05).

Conclusion

In SGA children, abnormal blood pressure values occurred more frequently than in AGA children.

Essential hypertension vs. secondary hypertension among children

BACKGROUND

The aim was to determine the proportions and correlates of essential hypertension among children in a tertiary pediatric hypertension clinic.

METHODS

We evaluated 423 consecutive children and collected demographic and clinical history by retrospective chart review.

RESULTS

We identified 275 (65%) hypertensive children (blood pressure >95th percentile per the "Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents") from 423 children referred to the clinic for history of elevated blood pressure. The remainder of the patients had normotension (11%), white coat hypertension (11%), prehypertension (10%), and pending diagnosis (3%). Among the 275 hypertensive children, 43% (n = 119; boys = 56%; median age = 12 years; range = 3-17 years) had essential hypertension and 57% (n = 156; boys = 66%; median age = 9 years; range = 0.08-19 years) had secondary hypertension. When compared with those with secondary hypertension, those with essential hypertension had a significantly older age at diagnosis (P = 0.0002), stronger family history of hypertension (94% vs. 68%; P < 0.0001), and lower prevalence of preterm birth (20% vs. 46%; P < 0.001). There was a bimodal distribution of age of diagnosis in those with secondary hypertension.

CONCLUSIONS

The phenotype of essential hypertension can present as early as 3 years of age and is the predominant form of hypertension in children after age of 6 years. Among children with hypertension, those with essential hypertension present at an older age, have a stronger family history of hypertension, and have lower prevalence of preterm birth.

Associations of prenatal growth with metabolic syndrome, insulin resistance, and nutritional status in Chilean children

Introduction. The association of prenatal growth with nutritional status, metabolic syndrome (MS), and insulin resistance (IR) was studied in school-age children. Methods. A retrospective cohort study was designed linking present data of children with perinatal records. 3325 subjects were enrolled. Anthropometry, blood pressure (BP), and pubertal status were assessed. Blood lipids, glucose, and insulin were measured. Linear associations were assessed using the Cochran-Armitage test. Odds ratios and nonlinear associations were computed. Results. 3290 children (52% females, mean age of 11.4 ± 1 years) were analyzed. Prevalence of obesity, stunting, MS, and IR was 16.0%, 3.6%, 7.3%, and 25.5%, respectively. The strongest positive association was between birth weight (BW) and obesity (OR 2.97 (95% CI 2.01–4.40) at BW ≥ 4,000 g compared to BW 2,500–2,999). The strongest inverse association was between birth length (BL) and stunting (OR 8.70 (95% CI 3.66–20.67) at BL < 48 cm compared to BL 52-53 cm). A U-shaped association between BL and BP ≥ 90th percentile was observed. Significant ORs were also found for MS and IR. Adjustments for present fat mass increased or maintained the most prenatal growth influences. Conclusions. Prenatal growth influences MS, IR, and nutritional status. Prenatal growth was more important than present body composition in determining these outcomes.

High rates of child hypertension associated with obesity: a community survey in China, India and Mexico

BACKGROUND

Hypertension is a significant risk factor for cardiovascular disease, and epidemiological evidence suggests that it is increasing in parallel with obesity in children and adolescents in low- and middle-income countries.

AIM

To identify and determine the relationship between overweight, obesity and hypertension in a community sample of school children.

METHODS

Anthropometric data were collected from 12,730 school children aged 12-18 years in China, India and Mexico as part of the Community Interventions for Health programme, an international study evaluating community interventions to reduce non-communicable disease by addressing the three main risk factors of tobacco use, unhealthy diets and physical inactivity. Logistic regression was used to examine the association of body mass index and gender and hypertension.

RESULTS

Prevalence rates of hypertension were 5.2% in China, 10.1% in India and 14.1% in Mexico, and pre-hypertension rates in China, India and Mexico were 13.4%, 9.4% and 11.2%, respectively. Overweight and obesity prevalence rates varied by country and were 16.6% in China, 4.1% in India and 37.1% in Mexico. In all countries there was a significant association between overweight and obesity and rates of hypertension. Overweight children were 1.7-2.3 times more likely to be hypertensive and obese children 3.5-5.5 more likely to show hypertension than those of normal weight.

CONCLUSIONS

Rates of hypertension and overweight and obesity are high in school children in China, India and Mexico, and increased bodyweight is a significant risk factor for hypertension.

Utilising infant growth to predict obesity status at 5 years

AIM

This study determines if an early life growth pattern in healthy infants can predict obesity at age 5.

METHODS

Randomly selected from all healthy children born from 1997 to 2001 in a Midwestern US Health Maintenance Organization; growth patterns from birth to 5 years were described for children who were categorised by obesity classification at 5 years into normal weight (n = 61), overweight (n = 47), obese (n = 41) and morbidly obese (n = 72) cohorts using World Health Organization body mass index (BMI) criteria. A retrospective longitudinal analysis based on weighted least squares was performed on BMI by age (1 week; 2, 4, 6, 9, 12, 15 and 18 months; and 2, 3, 4 and 5 years). Graphs of the longitudinal repeated measures analysis of variance of means allowed identification of the earliest significant divergence of a cohort's average BMI pattern from other cohorts' patterns.

RESULTS

Distinctions in growth patterns and BMIs were evident before 1-year post-birth. Children who were obese or morbidly obese at 5 years demonstrated a BMI pattern that differed from children who were normal weight at 5 years.

CONCLUSIONS

Identifying obesity development in early life may assist with prevention of later obesity. The results merit future study. An early life BMI growth pattern is clinically important because it permits discrimination of those who do and do not fit a normal weight pattern, guiding individualised interventions in the first year of life while precursors of later health are still forming.

Increased renal sympathetic nerve activity leads to hypertension and renal dysfunction in offspring from diabetic mothers

The exposure of the fetus to a hyperglycemic environment promotes the development of hypertension and renal dysfunction in the offspring at adult age. We evaluated the role of renal nerves in the hypertension and renal changes seen in offspring of diabetic rats. Diabetes was induced in female Wistar rats (streptozotocin, 60 mg/kg ip) before mating. Male offspring from control and diabetic dams were studied at an age of 3 mo. Systolic blood pressure measured by tail cuff was increased in offspring of diabetic dams (146 ± 1.6 mmHg, n = 19, compared with 117 ± 1.4 mmHg, n = 18, in controls). Renal function, baseline renal sympathetic nerve activity (rSNA), and arterial baroreceptor control of rSNA were analyzed in anesthetized animals. Glomerular filtration rate, fractional sodium excretion, and urine flow were significantly reduced in offspring of diabetic dams. Two weeks after renal denervation, blood pressure and renal function in offspring from diabetic dams were similar to control, suggesting that renal nerves contribute to sodium retention in offspring from diabetic dams. Moreover, basal rSNA was increased in offspring from diabetic dams, and baroreceptor control of rSNA was impaired, with blunted responses to infusion of nitroprusside and phenylephrine. Thus, data from this study indicate that in offspring from diabetic mothers, renal nerves have a clear role in the etiology of hypertension; however, other factors may also contribute to this condition.

Early determinants of chronic disease in developing countries

The prevalence of non-communicable diseases (NCDs) is rising in developing countries. The extent to which this is due to a nutritional mismatch in foetal and adult life is unknown however, studies in such countries show that the risk of chronic diseases is increased in low birthweight subjects who become obese adults. Immune dysfunction is also linked to low birthweight. Therefore, in countries where communicable diseases are prevalent, infection may be exacerbated by factors acting in utero. It is also possible that the foetal growth-retarding effects of maternal Human Immunodeficiency Virus (HIV) and malaria infection may contribute to an increased risk of NCDs later in life. Low birthweight and postnatal growth faltering followed by rapid weight gain define subjects who develop NCDs. Dietary interventions at specific time points in the life course may therefore be important for reducing disease risk.

Birth weight is inversely associated with blood pressure and serum aldosterone and cortisol levels in children

CONTEXT

Low birth weight has been independently associated with adult hypertension, and renin-angiotensin system (RAS) plays a role in this connection.

OBJECTIVE

To characterize the associations between birth weight (BW) and serum aldosterone (SA), serum cortisol, plasma renin activity (PRA) and blood pressure (BP).

DESIGN

Cross-sectional study.

SUBJECTS

Children from the community born at a gestational age >32 weeks.

METHODS

Systolic and diastolic BP indices (SBPi and DBPi) were calculated using the observed BP/50th percentile BP for gender, age and stature. BW was transformed to a standard deviation score (SDS) for gestational age, whereas SA, serum cortisol and PRA were transformed using the natural log.

RESULTS

We selected 288 subjects between the ages of 4·9 and 15·5 years (Females, 50%). After adjusting for body mass index (BMI) SDS and Tanner, multiple regression analysis revealed that BW (SDS) was both independently and inversely associated with the natural log of SA (β = -0·065; P = 0·039), the natural log of serum cortisol (β = -0·064; P = 0·009), SBPi (β = -0·012; P = 0·020) and DBPi (β = -0·023; P = 0·002). An association was not observed with PRA (P = 0·178) and aldosterone renin ratio (ARR) (P = 0·452). Serum cortisol levels were positively associated with SA (r = 0·125; P = 0·034), while an association with PRA (P = 0·251) and ARR (P = 0·052) was not observed.

CONCLUSIONS

The results of this study demonstrate an inverse association between birth weight and blood pressure and serum aldosterone and cortisol levels. This association is independent of BMI and Tanner, suggesting foetal programming of the hypothalamic-pituitary-adrenal axis.

Prenatal growth and metabolic syndrome components among Chilean children

The association of prenatal growth with metabolic syndrome (MS) components and insulin resistance (IR) in children has not been studied in Chile and most developing countries. Some associations found in developed countries are controversial. A retrospective cohort study was designed linking present information on MS components and IR in children with register-based information on birth weight (BW), birth length (BL) and gestational age (GA). Examinations included anthropometry and blood pressure (BP), as well as self-report of pubertal status. A fasting blood sample was taken to determine lipids, glucose, insulin and homeostasis model assessment (HOMA)-IR was calculated. The study cohort of 2152 children was on average 11.4 ± 1.0 years old. The prevalence of MS, IR and overweight were 7.6%, 24.5% and 34%, respectively. Elevated BP was negatively associated with dichotomized risk categories of the perinatal factors studied (BW, BL and GA). Contingency tables showed that high waist circumference (WC) and elevated BP had a U-shaped association with various categories of BW and BL, respectively. Stepwise linear regressions selected: (a) WC as inversely associated to GA and directly associated to BW, (b) BP as inversely associated to GA and (c) HOMA-IR as inversely associated to BL. Non-optimal prenatal growth seems to predispose to high WC, elevated BP and IR in school-age children, supporting the early life origin of several non-communicable diseases. Those associations were rather weak as estimated by the slopes of the regressions and probably reduced by their U-shaped nature; they would reasonably become stronger with a longer follow-up.

Trends in risk factors for cardiovascular disease among Iranian adolescents: the Tehran Lipid and Glucose Study, 1999-2008

OBJECTIVES

Data on secular trends in adolescent obesity and dyslipidemia are limited. Data on obesity status collected during 3 surveys were used to evaluate these trends in obesity and dyslipidemia among Tehranian adolescents and to assess the likelihood of risk factors for cardiovascular disease.

METHODS

We analyzed data for adolescents (age 10 to 19 years) from 3 cross-sectional surveys of the Tehran Lipid and Glucose Study: 1999-2001 (n = 3010, 47.2% males), 2002-2005 (n = 1107, 48.4% males), and 2006-2008 (n = 1090, 46.6% males). Overweight and abdominal obesity were defined using Iranian body mass index (BMI) percentiles, International Obesity Task Force (IOTF) criteria, and Iranian waist circumference (WC) charts. Hypertension was defined by using the National Heart, Lung, and Blood Institute's recommended cut points, and dyslipidemia was defined according to the recent recommendations of the American Heart Association.

RESULTS

The overall adjusted prevalences of "at risk for overweight" and overweight changed from 13% and 8% (using Iranian cutoffs), respectively, and 14.8% and 4.7% (using IOTF criteria) in 1999-2001 to 19% and 15% (Iranian cutoffs) and 23.0% and 9.2% (IOTF criteria) in 2006-2008 (P < 0.01 for all comparisons). The prevalence of abdominal obesity increased in males from 14.5% in 1999-2001 to 33.3% in 2006-2008 (P < 0.001). Almost half the adolescents had low high-density lipoprotein cholesterol (HDL-C) in the 3 surveys. In all surveys, as BMI and WC increased, multivariate age- and sex-adjusted odds ratios of low HDL-C and high triglyceride levels significantly increased. Overweight was associated with a greater likelihood of these risk factors, as compared with increased WC.

CONCLUSIONS

Overweight and abdominal obesity are increasing in Tehranian adolescents, and these increases are accompanied by abnormalities in levels of serum triglyceride and HDL-C.

Exploring determinants of secular decreases in childhood blood pressure and hypertension

BACKGROUND

Childhood blood pressure is largely uninfluenced by medical treatment and behavioral changes associated with hypertension diagnosis. Examining secular trends in childhood blood pressure and its contributing factors will help us better understand population-level determinants of blood pressure and hypertension.

METHODS AND RESULTS

Data were from 4 waves of the Korean National Health and Nutrition Examination Survey between 1998 and 2008, including a total of 5909 boys and girls 10 to 19 years of age. Over the past 10 years, age- and height-adjusted mean systolic blood pressure decreased substantially from 115.6 to 106.9 mm Hg (by 8.7 mm Hg) among boys and from 111.8 to 101.8 mm Hg (by 10.0 mm Hg) among girls. Associated childhood hypertension and prehypertension/hypertension prevalences decreased by 52% to 86%. These remarkable decreases were found among all age and socioeconomic groups and were not explained by secular changes in childhood obesity (body mass index and waist circumferences), health behaviors (cigarette smoking and physical activity), nutritional factors (sodium, potassium, total energy, protein, and fat intake), psychological factors (perceived stress and sleep duration), and sociodemographic factors (annual household income and family size).

CONCLUSIONS

We observed important population declines in blood pressure in Korea over a 10-year period in children 10 to 19 years of age, but the likely causes for these secular trends remain to be determined.

The relationship between birthweight and longitudinal changes of blood pressure is modulated by beta-adrenergic receptor genes: the Bogalusa Heart Study

This study examines the genetic influence of beta-adrenergic receptor gene polymorphisms (beta(2)-AR Arg16Gly and beta(3)-AR Trp64Arg) on the relationship of birthweight to longitudinal changes of blood pressure (BP) from childhood to adulthood in 224 black and 515 white adults, aged 21-47 years, enrolled in the Bogalusa Heart Study. Blacks showed significantly lower birthweight and frequencies of beta(2)-AR Gly16 and beta(3)-AR Trp64 alleles and higher BP levels and age-related trends than whites. In multivariable regression analyses using race-adjusted BP and birthweight, low birthweight was associated with greater increase in age-related trend of systolic BP (standardized regression coefficient beta = -0.09, P = .002) and diastolic BP (beta = -0.07, P = .037) in the combined sample of blacks and whites, adjusting for the first BP measurement in childhood, sex, age, and gestational age. Adjustment for the current body mass index strengthened the birthweight-BP association. Importantly, the strength of the association, measured as regression coefficients, was modulated by the combination of beta(2)-AR and beta(3)-AR genotypes for systolic (P = .042 for interaction) and diastolic BP age-related trend (P = .039 for interaction), with blacks and whites showing a similar trend in the interaction. These findings indicate that the intrauterine programming of BP regulation later in life depends on beta-AR genotypes.

Review and hypothesis: syndromes with severe intrauterine growth restriction and very short stature--are they related to the epigenetic mechanism(s) of fetal survival involved in the developmental origins of adult health and disease?

Diagnosing the specific type of severe intrauterine growth restriction (IUGR) that also has post-birth growth restriction is often difficult. Eight relatively common syndromes are discussed identifying their unique distinguishing features, overlapping features, and those features common to all eight syndromes. Many of these signs take a few years to develop and the lifetime natural history of the disorders has not yet been completely clarified. The theory behind developmental origins of adult health and disease suggests that there are mammalian epigenetic fetal survival mechanisms that downregulate fetal growth, both in order for the fetus to survive until birth and to prepare it for a restricted extra-uterine environment, and that these mechanisms have long lasting effects on the adult health of the individual. Silver-Russell syndrome phenotype has recently been recognized to be related to imprinting/methylation defects. Perhaps all eight syndromes, including those with single gene mutation origin, involve the mammalian mechanism(s) of fetal survival downsizing. Insights into those mechanisms should provide avenues to understanding the natural history, the heterogeneity and possible therapy not only for these eight syndromes, but for the common adult diseases with which IUGR is associated.

Size at birth is associated with blood pressure but not insulin resistance in 6–8 year old children in rural Nepal

Earlier, we reported that antenatal micronutrient supplementation reduced the risk of metabolic syndrome and microalbuminuria among offspring at 6–8 years of age in rural Nepal. In the same birth cohort, we examined associations of size at birth (weight, length and ponderal index), and gestational age, with cardiometabolic risk factors in childhood across all antenatal micronutrient interventions. There was an inverse association between birth weight and systolic blood pressure (SBP,β= −1.20 mm Hg/kg; 95% confidence interval (CI): −1.93, −0.46) and diastolic blood pressure (DBP,β= −1.24 mm Hg/kg; 95% CI: −2.00, −0.49). Current child body mass index was positively associated with SBP but not with DBP. Birth weight was unassociated with insulin resistance, but each kilogram of increase was associated with a reduced risk of high triglycerides (odds ratio (OR) = 0.64/kg; 95% CI: 0.41, 0.97) and an increased risk of high waist circumference (OR = 3.16/kg; 95% CI: 2.47, 4.41). In this rural Nepalese population of children 6–8 years of age with a high prevalence of undernutrition, size at birth was inversely associated with blood pressure and triglycerides and positively associated with waist circumference.

Glucocorticoid effects on the programming of AT1b angiotensin receptor gene methylation and expression in the rat

Adverse events in pregnancy may 'programme' offspring for the later development of cardiovascular disease and hypertension. Previously, using a rodent model of programmed hypertension we have demonstrated the role of the renin-angiotensin system in this process. More recently we showed that a maternal low protein diet resulted in undermethylation of the At1b angiotensin receptor promoter and the early overexpression of this gene in the adrenal of offspring. Here, we investigate the hypothesis that maternal glucocorticoid modulates this effect on fetal DNA methylation and gene expression. We investigated whether treatment of rat dams with the 11beta-hydroxylase inhibitor metyrapone, could prevent the epigenetic and gene expression changes we observed. Offspring of mothers subjected to a low protein diet in pregnancy showed reduced adrenal Agtr1b methylation and increased adrenal gene expression as we observed previously. Treatment of mothers with metyrapone for the first 14 days of pregnancy reversed these changes and prevented the appearance of hypertension in the offspring at 4 weeks of age. As a control for non-specific effects of programmed hypertension we studied offspring of mothers treated with dexamethasone from day 15 of pregnancy and showed that, whilst they had raised blood pressure, they failed to show any evidence of Agtr1b methylation or increase in gene expression. We conclude that maternal glucocorticoid in early pregnancy may induce changes in methylation and expression of the Agtr1b gene as these are clearly reversed by an 11 beta-hydroxylase inhibitor. However in later pregnancy a converse effect with dexamethasone could not be demonstrated and this may reflect either an alternative mechanism of this glucocorticoid or a stage-specific influence.

Hypertension in the developing world: challenges and opportunities

Hypertension is a major public health problem and a leading cause of death and disability in developing countries. One-quarter of the world's adult population has hypertension, and this is likely to increase to 29% by 2025. Modeled projections indicate an increase to 1.15 billion hypertensive patients by 2025 in developing countries. There is variability in the global prevalence of hypertension: hypertension is present in approximately 35% of the Latin American population, 20%-30% of the Chinese and Indian population, and approximately 14% in Sub-Saharan African countries. This heterogeneity has been attributed to several factors, including urbanization with its associated changes in lifestyle, racial ethnic differences, nutritional status, and birth weight. Compounding this high burden of hypertension is a lack of awareness and insufficient treatment in those with hypertension. The public health response to this challenge should drive greater promotion of awareness efforts, studies of risk factors for hypertension, and understanding of the impact of lifestyle changes. Also important are efforts to develop multipronged strategies for hypertension management in developing nations.

Enhanced post-natal growth is associated with elevated blood pressure in young Senegalese adults

BACKGROUND

Evidence suggests that intrauterine growth restriction followed by rapid post-natal growth is associated with high blood pressure. We assessed the effect of early size and post-natal growth on blood pressure in a population from West Africa, where fetal growth retardation and childhood malnutrition are common.

METHODS

A total of 1288 Senegalese subjects were followed from infancy to young adulthood (mean age 17.9 years). Adult systolic blood pressure (SBP) was regressed on infant and adult anthropometric characteristics.

RESULTS

In unadjusted analyses, infant size was positively associated with adult SBP (1.1 +/- 0.3; P = 0.001 for weight; 0.7 +/- 0.3; P = 0.04 for length). With adjustment for current size, the regression coefficients for infant size were reversed (-0.2 +/- 0.3; P = 0.51 for weight; -0.3 +/- 0.3; P = 0.35 for length). SBP increased by 4.1 and 2.9 mmHg for 1 standard deviation (SD) increase in current weight or height, respectively. No interaction between infant size and current size was found in the overall models (P = 0.11 for weight, P = 0.95 for height), but this term interacted with sex for weight effect. A negative interaction was found in males (-0.9 +/- 0.4; P = 0.02) but not in females (0.3 +/- 0.4; P = 0.46). The association of current weight with SBP was stronger in lighter weight male infants.

CONCLUSIONS

These findings support the hypothesis that subjects who were small in early life and experienced enhanced post-natal growth have higher levels of SBP, even in low-income settings.

Cardiorespiratory measures before and after feeding challenge in term infants are related to birth weight

AIM

This study tested the hypothesis that, within a few hours of delivery, cardiorespiratory measure taken during feeding provides markers of group differences related to birth weight. A secondary hypothesis was that high-frequency heart period variability would be related to underlying differences in autonomic control associated with birth weight.

METHODS AND SUBJECTS

One hundred four term infants in the lowest, middle, and highest birth weight quintiles were enrolled. Exclusion criteria were evidence of drug abuse, congenital anomalies, Apgar scores less than 7 or admission to the neonatal intensive care unit. Within 96 h of delivery, heart and respiratory rates, blood pressures and heart period variability were measured before, during and after feeding.

RESULTS

Term babies in the lowest quintile of birth weights have lower heart rates prior to feeding but greater increases in heart rate during the early postprandial period. Assessments of high-frequency heart period variability suggest that small term infants have greater parasympathetic tone before feeding and more sustained parasympathetic withdrawal following feeding.

CONCLUSION

Measurements of cardiorespiratory functions before and after feeding are related to birth weight and may provide markers that can help identify the most vulnerable of infants with small size at birth.

Blood pressure levels in childhood: probing the relative importance of birth weight and current size

Several studies have reported data supporting the idea that an impaired intrauterine environment that deprives the fetus of optimal nutrient delivery results in the predisposition of the fetus to experience cardiovascular and metabolic dysfunction in later life. However, contradictory data still exist. Our purpose was to investigate the effects of both birth weight and weight gain on the risk for high blood pressure levels in 6- to 10-year-old children. This cross-sectional study included 739 children divided into quartiles of birth weight. The mean values of both systolic and diastolic pressure were significantly different between quartiles of birth weight, with increasing blood pressure values as the birth weight decreased (P<0.001). Covariance analysis adjusting for gender, prematurity, and body mass index (BMI) showed that both systolic and diastolic pressure remained greater in the lowest than in the highest birth weight quartile. Separating those with low and normal birth weight demonstrated that the risk of childhood hypertension was significantly higher among children with low birth weight and current obesity (odds ratio [OR]: 5.0, confidence interval [CI]: 3.3 to 16.1; P=0.023). The inverse association between birth weight and blood pressure levels appears to be programmed during fetal life, while weight gain during childhood adds to this risk.

Perinatal taurine depletion increases susceptibility to adult sugar-induced hypertension in rats

This study tests the hypothesis that perinatal taurine depletion produces autonomic nervous system dysregulation and increases arterial pressure in young male rats maintained on a high sugar diet. Sprague-Dawley dams were either taurine depleted (beta-alanine 3% in water) or left untreated from conception to weaning. Their male offspring were fed normal rat chow with or without 5% glucose. At 7-8 weeks of age, the male offspring were either tested in a conscious, unrestrained state or after anesthetia. Body weight was slightly lower in the taurine-depleted rats although their heart or kidneys to body weight ratios were similar. Plasma potassium, blood urea nitrogen, plasma creatinine, hematocrit, fasting blood glucose concentrations and glucose tolerance were all similar. In the taurine-depleted, high glucose group, mean arterial pressure and sympathetic nervous system activity were increased while baroreflex function was impaired. These findings suggest that in this model perinatal taurine depletion causes autonomic nervous system dysfunction that may contribute to dietary high sugar-induced hypertension.

Immediate postnatal growth is associated with blood pressure in young adulthood: the Barry Caerphilly Growth Study

There is a consistent inverse association between birth weight and systolic blood pressure; however, few studies have been able to examine the immediate postnatal period. We have examined whether accelerated postnatal growth predicts adult systolic and diastolic blood pressure. We followed up participants from the Barry Caerphilly Growth Study. Blood pressure data were obtained on 679 of the original 951 subjects (73%) aged approximately 25 years. Both multivariable linear regression and spline models were used to examine the association among weight, length, and growth velocities with systolic blood pressure and diastolic blood pressure. Both statistical approaches showed that birth weight was inversely associated with systolic blood pressure. Only the spline models found that immediate (0 to 5 months) weight gain (beta coefficient: 1.29 mm Hg; 95% CI: 0.36 to 2.23; P=0.007) and weight gain between 1 year and 9 months to 5 years (beta coefficient: 1.44 mm Hg; 95% CI: 0.31 to 2.57; P=0.01) were independently associated with systolic blood pressure, whereas only immediate weight gain (beta coefficient: 0.74 mm Hg; 95% CI: 0.08 to 1.41; P=0.03) was associated with diastolic blood pressure. This is the first study to demonstrate that only immediate postnatal growth predicts diastolic blood pressure in term births, whereas it adds further evidence that both birth weight and postnatal growth are associated with systolic blood pressure in support of both the fetal origins and growth acceleration hypotheses.

In vivo quantification of embryonic and placental growth during gestation in mice using micro-ultrasound

BACKGROUND

Non-invasive micro-ultrasound was evaluated as a method to quantify intrauterine growth phenotypes in mice. Improved methods are required to accelerate research using genetically-altered mice to investigate the interactive roles of genes and environments on embryonic and placental growth. We determined (1) feasible age ranges for measuring specific variables, (2) normative growth curves, (3) accuracy of ultrasound measurements in comparison with light microscopy, and (4) weight prediction equations using regression analysis for CD-1 mice and evaluated their accuracy when applied to other mouse strains.

METHODS

We used 30-40 MHz ultrasound to quantify embryonic and placental morphometry in isoflurane-anesthetized pregnant CD-1 mice from embryonic day 7.5 (E7.5) to E18.5 (full-term), and for C57Bl/6J, B6CBAF1, and hIGFBP1 pregnant transgenic mice at E17.5.

RESULTS

Gestational sac dimension provided the earliest measure of conceptus size. Sac dimension derived using regression analysis increased from 0.84 mm at E7.5 to 6.44 mm at E11.5 when it was discontinued. The earliest measurement of embryo size was crown-rump length (CRL) which increased from 1.88 mm at E8.5 to 16.22 mm at E16.5 after which it exceeded the field of view. From E10.5 to E18.5 (full term), progressive increases were observed in embryonic biparietal diameter (BPD) (0.79 mm to 7.55 mm at E18.5), abdominal circumference (AC) (4.91 mm to 26.56 mm), and eye lens diameter (0.20 mm to 0.93 mm). Ossified femur length was measureable from E15.5 (1.06 mm) and increased linearly to 2.23 mm at E18.5. In contrast, placental diameter (PD) and placental thickness (PT) increased from E10.5 to E14.5 then remained constant to term in accord with placental weight. Ultrasound and light microscopy measurements agreed with no significant bias and a discrepancy of less than 25%. Regression equations predicting gestational age from individual variables, and embryonic weight (BW) from CRL, BPD, and AC were obtained. The prediction equation BW = -0.757 + 0.0453 (CRL) + 0.0334 (AC) derived from CD-1 data predicted embryonic weights at E17.5 in three other strains of mice with a mean discrepancy of less than 16%.

CONCLUSION

Micro-ultrasound provides a feasible tool for in vivo morphometric quantification of embryonic and placental growth parameters in mice and for estimation of embryonic gestational age and/or body weight in utero.

Prenatal dexamethasone 'programmes' hypotension, but stress-induced hypertension in adult offspring

Low birth weight in humans is predictive of hypertension in adult life. Although the mechanisms underlying this link remain unknown, fetal overexposure to glucocorticoids has been implicated. We previously showed that prenatal dexamethasone (DEX) exposure in the rat lowers birth weight and programmes adult hypertension. The current study aimed to further investigate the nature of this hypertension and to elucidate its origins. Unlike previous studies, we assessed offspring blood pressure (BP) with radiotelemetry, which is unaffected by stress artefacts of measurement. We show that prenatal DEX during the last week of pregnancy results in offspring of low birth weight (14% reduction) that have lower basal BP in adulthood ( approximately 4-8 mmHg lower); with the commonly expected hypertensive phenotype only being noted when these offspring are subjected to even mild disturbance or a more severe stressor (up to 30 mmHg higher than controls). Moreover, DEX-treated offspring sustain their stress-induced hypertension for longer. Promotion of systemic catecholamine release (amphetamine) induced a significantly greater rise of BP in the DEX animals (77% increase) over that observed in the vehicle controls. Additionally, we demonstrate that the isolated mesenteric vasculature of DEX-treated offspring display greater sensitivity to noradrenaline and other vasoconstrictors. We therefore conclude that altered sympathetic responses mediate the stress-induced hypertension associated with prenatal DEX programming.

Has blood pressure increased in children in response to the obesity epidemic?

The associations between elevated blood pressure and overweight, on one hand, and the increasing prevalence over time of pediatric overweight, on the other hand, suggest that the prevalence of elevated blood pressure could have increased in children over the last few decades. In this article we review the epidemiologic evidence available on the prevalence of elevated blood pressure in children and trends over time. On the basis of the few large population-based surveys available, the prevalence of elevated blood pressure is fairly high in several populations, whereas there is little direct evidence that blood pressure has increased during the past few decades despite the concomitant epidemic of pediatric overweight. However, a definite conclusion cannot be drawn yet because of the paucity of epidemiologic studies that have assessed blood pressure trends in the same populations and the lack of standardized methods used for the measurement of blood pressure and the definition of elevated blood pressure in children. Additional studies should examine if favorable secular trends in other determinants of blood pressure (eg, dietary factors, birth weight, etc) may have attenuated the apparently limited impact of the epidemic of overweight on blood pressure in children.

Exposure-measurement error is frequently ignored when interpreting epidemiologic study results

INTRODUCTION

One important source of error in study results is error in measuring exposures. When interpreting study results, one should consider the impact that exposure-measurement error (EME) might have had on study results.

METHODS

To assess how often this consideration is made and the form it takes, journal articles were randomly sampled from original articles appearing in the American Journal of Epidemiology and Epidemiology in 2001, and the International Journal of Epidemiology between December 2000 and October 2001.

RESULTS

Twenty-two (39%) of the 57 articles surveyed mentioned nothing about EME. Of the 35 articles that mentioned something about EME, 16 articles described qualitatively the effect EME could have had on study results. Only one study quantified the impact of EME on study results; the investigators used a sensitivity analysis. Few authors discussed the measurement error in their study in any detail.

CONCLUSIONS

Overall, the potential impact of EME on error in epidemiologic study results appears to be ignored frequently in practice.

Geographical variation in neonatal phenotype

BACKGROUND

Recent studies have shown associations between size and body proportions at birth and health outcomes throughout the life cycle, but there are few data on how neonatal phenotype varies in different populations around the world.

METHODS

Data from the UK, Finland, India, Sri Lanka, China, DR Congo, Nigeria, and Jamaica (n=22,067) were used to characterize geographical differences in phenotype in singleton, live-born newborns. Measurements included birth weight, placental weight, length, head, chest, abdominal and arm circumferences, and skinfolds.

RESULTS

Neonates in Europe were the largest, followed by Jamaica, East Asia (China), then Africa and South Asia. Birth weight varied widely (mean values 2,730-3,570 g), but in contrast, head circumference was similar in all except China (markedly smaller). The main difference in body proportions between populations was the head to length ratio, with small heads relative to length in China and large heads relative to length in South Asia and Africa.

CONCLUSIONS

These marked geographical differences in neonatal phenotype need to be considered when investigating determinants of fetal growth, and optimal phenotype for short-term and long-term outcomes.

Racial disparities in the association between birth weight in the term infant and blood pressure at age 7 years: results from the collaborative perinatal project

BP has been inversely associated with birth weight in studies worldwide, but few studies have included black individuals. The US National Collaborative Perinatal Project followed 58,960 pregnant women and their resultant offspring for 7 yr. In this post hoc analysis, all term white or black children without kidney or heart disease were included (n = 29,710). The effect of birth weight and other risk factors on systolic (SBP) and diastolic BP (DBP) was evaluated at 7 yr. Mean birth weight and body mass index at 7 yr were slightly lower for black compared with white children (birth weight 3.14 +/- 0.48 versus 3.32 +/- 0.46 kg [P < 0.001]; body mass index 15.8 +/- 2.0 versus 16.3 +/- 2.0 [P < 0.001]). Compared with white mothers, black mothers were less likely to smoke (41 versus 52%), were more anemic (23 versus 7%), and were more likely to live in poverty (72 versus 39%). In linear regression, there was significant interaction between race and birth weight in predicting SBP (P = 0.002). In bivariate analysis, birth weight was positively associated with SBP (beta = 0.87) and DBP (beta = 1.14) in black children (P < 0.001) but not associated with either in white children. With maternal poverty, educational level, and anemia during pregnancy added to the model, birth weight remained a significant positive predictor of SBP (beta = 0.89, P < 0.001) in black but not in white children (beta = 0.02, P = 0.17). The association between birth weight and SBP differs between black and white children. The cause of intrauterine growth restriction-associated hypertension seems to be race sensitive; therefore, future studies of racial disparities in the "Barker hypothesis" may help in the understanding of the mechanism of fetal programming of hypertension.

Effects of low birth weight in 8- to 13-year-old children: implications in endothelial function and uric acid levels

Low birth weight has been associated with an increased incidence of adult cardiovascular disease. Endothelial dysfunction and high levels of serum uric acid are associated with hypertension. In this study, we have determined whether uric acid is related to blood pressure and vascular function in children with low birth weight. We evaluated vascular function using high-resolution ultrasound, blood pressure, and uric acid levels in 78 children (35 girls, 43 boys, aged 8 to 13 years). Increasing levels of uric acid and systolic blood pressure were observed in children with low birth weight. Birth weight was inversely associated with both systolic blood pressure and uric acid; on the other hand, uric acid levels were directly correlated with systolic blood pressure in children of the entire cohort. Low birth weight was associated with reduced flow-mediated dilation (r=0.427, P<0.001). Because the children with low birth weight had elevated uric acid as well as higher systolic blood pressure levels, we evaluated the correlation between these variables. In the low birth weight group, multiple regression analysis revealed that uric acid (beta=-2.886; SE=1.393; P=0.040) had a graded inverse relationship with flow-mediated dilation, which was not affected in a model adjusting for race and gender. We conclude that children with a history of low birth weight show impaired endothelial function and increased blood pressure and uric acid levels. These findings may be early expressions of vascular compromise, contributing to susceptibility to disease in adult life.

Adult hypertension and kidney disease: the role of fetal programming

Hypertension (HTN) and chronic kidney disease are highly prevalent diseases that tend to occur more frequently among disadvantaged populations, in whom prenatal care also tends to be poor. More and more evidence is emerging highlighting the important role of fetal programming in the development of adult disease, suggesting a possible common pathophysiologic denominator in the development of these disorders. Epidemiologic evidence accumulated over the past 2 decades has demonstrated an association between low birth weight and subsequent adult HTN, diabetes, and cardiovascular disease. More recently, a similar association has been found with chronic kidney disease. Animal studies and indirect evidence from human studies support the hypothesis that low birth weight, as a marker of adverse intrauterine circumstances, is associated with a congenital deficit in nephron number. The precise mechanism of the reduction in nephron number has not been established, but several hypotheses have been put forward, including changes in DNA methylation, increased apoptosis in the developing kidney, alterations in renal renin-angiotensin system activity, and increased fetal glucocorticoid exposure. A reduction in nephron number is associated with compensatory glomerular hypertrophy and an increased susceptibility to renal disease progression. HTN in low birth weight individuals also appears to be mediated in part through a reduction in nephron number. Increased awareness of the implications of low birth weight and inadequate prenatal care should lead to public health policies that may have long-term benefits in curbing the epidemics of HTN, diabetes, and kidney disease in generations to come.

Low birth weight, nephron number, and kidney disease

More and more evidence is emerging that highlights the far-reaching consequences of prenatal (intrauterine) programming on organ function and adult disease. In humans, low birth weight (LBW) occurs more frequently in disadvantaged communities among whom there is often a disproportionately high incidence of adult cardiovascular disease, hypertension, diabetes mellitus, and kidney disease. Indeed, many epidemiologic studies have found an inverse association between LBW and higher blood pressures in infancy and childhood, and overt hypertension in adulthood. Multiple animal models have demonstrated the association of LBW with later hypertension, mediated, at least in part, by an associated congenital nephron deficit. Although no direct correlation has been shown between nephron number and birth weight in humans with hypertension, nephron numbers were found to be lower in adults with essential hypertension, and glomeruli tend to be larger in humans of lower birth weight. An increase in glomerular size is consistent with hyperfiltration necessitated by a reduction in total filtration surface area, which suggests a congenital nephron deficit. Hyperfiltration manifests clinically as microalbuminuria and accelerated loss of renal function, the prevalence of which are higher among adults who had been of LBW. A kidney with a reduced nephron number has less renal reserve to adapt to dietary excesses or to compensate for renal injury, as is highlighted in the setting of renal transplantation, where smaller kidney to recipient body-weight ratios are associated with poorer outcomes, independent of immunologic factors. Both hypertension and diabetes are leading causes of end-stage renal disease worldwide, and their incidences are increasing, especially in underdeveloped communities. Perinatal programming of these 2 diseases, as well as of nephron number, may therefore have a synergistic impact on the development of hypertension and kidney disease in later life. Existing evidence suggests that birth weight should be used as a surrogate marker for future risk of adult disease. Although the ideal solution to minimize morbidity would be to eradicate LBW, until this panacea is realized, it is imperative to raise awareness of its prognostic implications and to focus special attention toward early modification of risk factors for cardiovascular and renal disease in individuals of LBW.

The association of fat patterning with blood pressure in rural South African children: the Ellisras Longitudinal Growth and Health Study

BACKGROUND

Hypertension is one of the major causes of death in developed and underdeveloped nations. Essential hypertension and obesity may have their inception in childhood, with little data in African children to support these findings. Objectives were to determine the prevalence of overweight and hypertension in rural children in South Africa. Additionally, the association between fat-patterning ratios and blood pressure (BP) was investigated.

METHODS

Data were collected from 1884 subjects (967 boys and 917 girls), aged 6-13 years, participating in the Ellisras Longitudinal Study. Height; weight; and triceps, biceps, subscapular, and suprailiac skinfolds were measured according to the protocol of the International Society for the Advancement of Kinanthropometry. Skinfold ratio was used as an indicator of the central pattern of body fat. Internationally recommended cut-off points for body mass index (BMI) were used. Hypertension, defined as the average of three separate BP readings where the systolic BP or diastolic BP is >or=95th percentile for age and sex, was determined.

RESULTS

The prevalence of hypertension ranged from 1 to 5.8% for boys and 3.1 to 11.4% for girls, and that of overweight from 1.1 to 2.9% for boys and 0.6 to 4.6% for girls. The association between high systolic BP and high BMI was -3.0, while that for high diastolic BP and high BMI was -0.68.

CONCLUSIONS

The prevalence of hypertension is evident from the age 6 years for girls, while that of overweight was low. Overweight became evident from the age 10 to 13 years for both sexes. A significant association between high diastolic BP and high BMI was noted, while children with low BMIs were less likely to be hypertensive. Investigating habitual physical activity, fitness and dietary patterns will shed more light on the association of fat patterning and BP in this population.

Racial disparities in the association of foetal growth retardation to childhood blood pressure

BACKGROUND

Foetal growth retardation (FGR), defined as less than the 10th percentile of birth weight for gestational age, is reported to be an important contributor to hypertension and cardiovascular disease in children and adults, but findings are not consistent. For this reason we re-examined the role of FGR in childhood blood pressure.

METHODS

We performed univariate and multivariate analyses on data gathered from 262 children, age 5 years, born to mothers at risk for pre-term delivery or FGR infant. The characteristics of the mothers and the children were evaluated using Student's t-test. Rates and proportions were compared using either chi-square or Fisher's exact test. Linear regression models evaluated the effect of birth weight and body mass index on systolic and diastolic blood pressure. Multivariate linear regression was used to model the effects of FGR, gestational age, body mass index, race, gender, maternal smoking, maternal gestational diabetes on blood pressure while adjusting for possible confounders.

RESULTS

Systolic blood pressure was inversely associated with birth weight in white children while a small direct association was noted in African Americans. Body mass index was positively associated with systolic blood pressure in both groups. Multiple linear regression analyses showed FGR and early gestational age were associated with higher blood pressure in white but not African American children, accounting for a 13.2 mmHg difference between FGR and appropriate for gestational age groups. Blood pressure in African Americans was strongly affected by maternal gestational diabetes and smoking.

CONCLUSIONS

Birth weight influences childhood blood pressure but the effects may vary depending on ethnic group. The relative importance of birth weight on blood pressure may depend on other prenatal and post-partum risks.

Maternal and childhood nutrition and later blood pressure levels in young Guatemalan adults

BACKGROUND

Low birth weight and subsequent rapid child growth are associated with later blood pressure levels. The role of maternal and child nutrition in this association remains unclear.

METHODS

We studied 450 men and women (ages 21-29 years) born during a randomized trial of protein-energy supplementation (Atole) vs low energy/no protein supplementation (Fresco) in pregnancy and early childhood in four rural Guatemalan villages from 1969 to 1977.

RESULTS

Protein-energy supplementation was not associated with differences in blood pressure in adulthood (diastolic blood pressure (DBP): beta = 0.69 mm Hg, 95% confidence internal (CI) (20.82-2.19); P = 0.37; systolic blood pressure (SBP): beta = 0.17 mm Hg, 95% CI (21.68-2.02); P = 0.86). Within the Atole group, maternal height was associated with later SBP (0.22 mm Hg/cm, 95% CI (20.002-0.45); P = 0.05). No other associations between maternal nutritional status, birth size, child growth, or supplement intake were observed for adult blood pressure.

CONCLUSIONS

Our data do not support the role of maternal nutrition during pregnancy, birth size, or early child growth in programming adult blood pressure. Likewise, we found no effect of protein-energy supplementation in pregnancy or in early childhood on blood pressure in young adults.

Low preconception body mass index is associated with birth outcome in a prospective cohort of Chinese women

Low maternal prepregnancy BMI is associated with adverse birth outcomes, but the BMI at which risk increases is not well defined. We assessed whether the relationship between prepregnancy BMI and birth outcomes is influenced by the extent to which mothers were underweight in a prospective study in Anhui, China. The women (n = 575) were 20-34 y old, married, nulliparous and nonsmokers. All measures of infant growth increased with increasing maternal BMI until a plateau was reached at a BMI of 22-23 kg/m2. Infants born to the 27% of women who were severely underweight before pregnancy (BMI < or = 18.5 kg/m2) were at increased risk for fetal growth deficits associated with infant morbidity. Compared with a normal BMI, being severely underweight was associated with mean (+/- SEM) reductions of 219 +/- 40 g in infant birthweight and 6.7 +/- 1.3% in the birthweight ratio and an 80% increase in risk of intrauterine growth restriction [odds ratio (OR) 1.8; 95% CI: 1.0, 3.3; P = 0.05]. Being severely underweight was also associated with smaller infant head circumference and lower ponderal index. Being moderately underweight (18.5 < BMI < 19.8 kg/m2) was not significantly associated with adverse pregnancy outcomes. Gestational age and risk of preterm birth were not associated with maternal BMI. More than half of the women in this study were underweight before pregnancy. Although being moderately underweight was not associated with increased risk of adverse pregnancy outcomes, being severely underweight was an important risk factor for reduced fetal growth.

A life course approach to diet, nutrition and the prevention of chronic diseases

OBJECTIVE

To briefly review the current understanding of the aetiology and prevention of chronic diseases using a life course approach, demonstrating the life-long influences on the development of disease.

DESIGN

A computer search of the relevant literature was done using Medline-'life cycle' and 'nutrition' and reviewing the articles for relevance in addressing the above objective. Articles from references dated before 1990 were followed up separately. A subsequent search using Clio updated the search and extended it by using 'life cycle', 'nutrition' and 'noncommunicable disease' (NCD), and 'life course'. Several published and unpublished WHO reports were key in developing the background and arguments.

SETTING

International and national public health and nutrition policy development in light of the global epidemic in chronic diseases, and the continuing nutrition, demographic and epidemiological transitions happening in an increasingly globalized world. RESULTS OF REVIEW: There is a global epidemic of increasing obesity, diabetes and other chronic NCDs, especially in developing and transitional economies, and in the less affluent within these, and in the developed countries. At the same time, there has been an increase in communities and households that have coincident under- and over-nutrition.

CONCLUSIONS

The epidemic will continue to increase and is due to a lifetime of exposures and influences. Genetic predisposition plays an unspecified role, and with programming during fetal life for adult disease contributing to an unknown degree. A global rise in obesity levels is contributing to a particular epidemic of type 2 diabetes as well as other NCDs. Prevention will be the most cost-effective and feasible approach for many countries and should involve three mutually reinforcing strategies throughout life, starting in the antenatal period.

Iron deficiency during pregnancy affects postnatal blood pressure in the rat

Iron (Fe) deficiency anaemia during pregnancy results in an increased risk of perinatal mortality and morbidity and is a significant factor for increased risk of disease in later life. Consequently we have developed a rat model to study the relationship between maternal Fe deficiency and postnatal growth and blood pressure in the offspring. Weanlings were fed a control or Fe-deficient diet prior to and throughout pregnancy. At term, all pups were cross-fostered to control fed dams and weaned onto control diet. At birth, pups from deficient dams had a greater mortality rate, were smaller and had reduced haematocrit and liver Fe levels. They also had larger hearts, smaller kidneys and spleens and unchanged livers (relative organ weight). The pups grew normally. At 6 weeks, male pups from deficient dams had a higher and females a lower blood pressure than their normal counterparts. At 10 and 16 weeks, blood pressure in the males from deficient dams was still raised and in the females was now greater than controls. The haematocrit was lower in males throughout the 16 weeks and in females until 10 weeks of age. There was no significant difference in the offsprings' liver Fe stores at 6, 10 or 16 weeks. Duodenal Fe uptake in both the Fe-deficient mother and newborn offspring was significantly increased. By cross-fostering, we have eliminated confounding factors, such as maternal anaemia during lactation and show, unequivocally, that prenatal nutrition is critical for the development of normal postnatal function.