Increased blood pressure in adolescents who were small for gestational age at birth: a cohort study in Brazil

Effect of preterm birth on growth and blood pressure in adulthood in the Pelotas 1993 cohort

BACKGROUND

Preterm birth has been associated with increased risk of hypertension and cardiovascular disease later in adulthood, attributed to cardiovascular and metabolic alterations in early life. However, there is paucity of evidence from low- and middle-income countries (LMICs).

METHODS

We investigated the differences between preterm (<37 weeks gestational age) and term-born individuals in birth length and weight as well as adult (18 and 20 years) height, weight and blood pressure in the Brazilian 1993 Pelotas birth cohort using linear regressions. Analyses were adjusted for the maternal weight at the beginning of pregnancy and maternal education and family income at childbirth. Additional models were adjusted for body mass index (BMI) and birthweight. Separate analyses were run for males and females. The complete sample was analysed with an interaction term for sex.

RESULTS

Of the 3585 babies included at birth, 3010 were followed up in adulthood at 22 years. Preterm participants had lower length and weight at birth. This difference remained for male participants in adulthood, but female participants were no shorter than their term counterparts by 18 years of age. At 22 years, females born preterm had lower blood pressures (systolic blood pressure -1.00 mmHg, 95%CI -2.7, 0.7 mmHg; diastolic blood pressure -1.1 mmHg, 95%CI -2.4, 0.3 mmHg) than females born at term. These differences were not found in male participants.

CONCLUSIONS

In this Brazilian cohort we found contrasting results regarding the association of preterm birth with blood pressure in young adulthood, which may be unique to an LMIC.

Are small-for-gestational-age preterm infants at increased risk of overweight? Statistical pitfalls in overadjusting for body size measures

OBJECTIVE

The objective of this study is to analyze the effect of adjusting for body measures on the association between small for gestational age (SGA) and overweight at 3 years.

STUDY DESIGN

Data were obtained from the Preterm Infant Multicenter Growth Study (n = 1089). Logistic regression was used, to adjust for confounders with additional adjustments separately for weight and height at 21 months. Marginal structural models (MSMs) estimated the direct effect of SGA on overweight.

RESULTS

The crude and adjusted for confounders models yielded null associations between SGA and overweight. Adjusting for height yielded a positive association (odds ratio (OR): 2.31, 95% CI: 0.52-10.26) and adjusting for weight provided a significantly positive association (OR: 6.60, 95% CI: 1.10-37.14). The MSMs, with height and weight held constant, provided no evidence for a direct effect of SGA on overweight (OR: 0.83, 95% CI: 0.14-5.01, OR: 0.71, 95% CI: 0.18-2.81, respectively).

CONCLUSION

Adjusting for body measures can change the association between SGA and overweight, providing spurious estimates.

Factors Associated with Primary Hypertension in Pediatric Patients: An Up-to-Date

BACKGROUND

Arterial hypertension in children is considered a common alteration nowadays, mainly because obesity is a growing worldwide problem closely related to increased blood pressure. Childhood hypertension can be classified as primary or secondary, depending on the etiology. Primary or essential hypertension still has its pathophysiology not fully elucidated, and there is no consensus in the literature on most underlying mechanisms. In this review, genetic and environmental factors, including sodium and potassium intake, socioeconomic status, ethnicity, family structure, obesity, sedentary lifestyle, prematurity and low birth weight, prenatal and postnatal exposures are highlighted.

OBJECTIVE

The present study aimed to perform an update on primary hypertension in childhood, providing clinicians and researchers an overview of the current state of the literature regarding the influence of genetic and environmental factors.

METHODS

This integrative review searched for articles on genetic and environmental factors related to primary hypertension in pediatric patients. The databases evaluated were PubMed and Scopus.

RESULTS

The studies have provided insights regarding many genetic and environmental factors, in addition to their association with the pathophysiology of primary hypertension in childhood. Findings corroborated the idea that primary hypertension is a multifactorial disease. Further studies in the pediatric population are needed to elucidate the underlying mechanisms.

CONCLUSION

The study of primary hypertension in pediatrics has utmost importance for the adoption of preventive measures and the development of more efficient treatments, therefore reducing childhood morbidity and the incidence of cardiovascular diseases and other health consequences later in life.

Cardiovascular risk factors in those born preterm - systematic review and meta-analysis

Emerging evidence demonstrates a link between preterm birth (PTB) and later life cardiovascular disease (CVD). We conducted a systematic review and meta-analysis to compare conventional CVD risk factors between those born preterm and at term. PubMed, CINAHL, SCOPUS, and EMBASE databases were searched. The review protocol is registered in PROSPERO (CRD42018095005). CVD risk factors including systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index, lipid profile, blood glucose, and fasting insulin among those born preterm (<37 weeks' gestation) were compared with those born at term (≥37 weeks' gestation). Subgroup analyses based on gender, age, gestational at birth (<32 weeks' gestation and <28 weeks' gestation), and PTB associated with small for gestational age or average for gestational age were also performed. Fifty-six studies provided data on 308,987 individuals. Being born preterm was associated with 3.26 mmHg (95% confidence interval [CI] 2.08 to 4.44) higher mean SBP and 1.32 mmHg (95% CI: 0.61 to 2.04) higher mean DBP compared to being born at term. Subgroup analyses demonstrated that SBP was higher among (a) preterm compared to term groups from early adolescence until adulthood; (b) females born preterm but not among males born preterm compared to term controls; and (c) those born at <32 weeks or <28 weeks compared to term. Our meta-analyses demonstrate higher SBP and DBP among those born preterm compared to term. The difference in SBP is evident from early adolescence until adulthood.

Conflicting Effects of Fetal Growth Restriction on Blood Pressure Between Human and Rat Offspring: A Meta-Analysis

Low birth weight is associated with hypertension. Low birth weight can result from fetal growth restriction (FGR) or prematurity. FGR is postulated to impact blood pressure (BP) by developmental programming. This systematic review and meta-analysis studies BP in human and animal offspring following FGR. Pubmed and Web of Science were searched for studies reporting on BP after placental insufficiency induced FGR compared with normal growth controls. Primary outcome was mean absolute BP difference (ΔBP mm Hg [95% CI]). Meta-analysis was performed using random-effects models. Subgroup analyses were executed on species, sex, age, pregnancy duration, and stress during BP readings. Due to large interspecies heterogeneity, analyses were performed separately for human (n=41) and animal (n=31) studies, the latter restricted to rats (n=27). Human studies showed a ΔBP between FGR and controls of -0.6 mm Hg ([95% CI, -1.7 to 0.6]; I²=91%). Mean ΔBP was -2.6 mm Hg (95% CI, -5.7 to 0.4) in women versus -0.5 mm Hg (95% CI, -3.7 to 2.7) in men. Subgroup analyses did not indicate age, gestational age, and stress during measurements as sources of heterogeneity. In rats, mean BP was 12.0 mm Hg ([95% CI, 8.8-15.2]; I²=81%) higher in FGR offspring. This difference was more pronounced in FGR males (13.6 mm Hg [95% CI, 10.3-17.0] versus 9.1 mm Hg [95% CI, 5.3-12.8]). Subgroup analyses on age showed no statistical interaction. BP readings under restrained conditions resulted in larger BP differences between FGR and control rats (15.3 mm Hg [95% CI, 11.6-18.9] versus 5.7 mm Hg [95% CI, 1.1-10.3]). Rat studies confirm the relation between FGR and offspring BP, while observational studies in humans do not show such differences. This may be due to the observational nature of human studies, methodological limitations, or an absence of this phenomenon in humans. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: CRD42018091819.

Association of intrauterine exposure to aspirin and blood pressure at 7 years of age: a secondary analysis

OBJECTIVE

To examine whether maternal aspirin use during pregnancy is associated with childhood blood pressure.

DESIGN/SETTING

A secondary analysis of the Collaborative Perinatal Project, a prospective cohort study including 12 US academic medical centres between 1959 and 1976.

POPULATION

Singleton births among women with detailed medication information.

METHODS

We carried out linear and multivariate logistic regression analysis to assess the associations between maternal aspirin exposure and childhood blood pressure at age 7 years.

MAIN OUTCOME MEASURES

Offspring blood pressure at age 7 years.

RESULTS

A total of 15 793 women were exposed to aspirin 4 weeks before the last menstrual period or during pregnancy. In utero aspirin exposure may be associated with an 11% (95% CI 0.85- 0.93) and a 20% (95% CI 0.76-0.84) reduced risk of having high systolic blood pressure (SBP) and diastolic blood pressure (DBP) at 7 years of age, and a mean decrease of 0.62 mmHg for SBP and 1.04 mmHg for DBP at 7 years of age. Compared with children born to mothers without aspirin exposure, those whose mothers were exposed to aspirin for at least 7 days during pregnancy had approximately 10% and 27% reduced risk of high SBP and DBP, respectively, and a mean reduction of 0.61 and 1.27 mmHg in SBP and DBP at 7 years of age. The earlier the aspirin exposure occurred during pregnancy, the lower the risk of childhood high blood pressure.

CONCLUSION

In utero exposure to aspirin may have long-term benefits for childhood blood pressure.

TWEETABLE ABSTRACT

Maternal aspirin exposure might decrease the risk of childhood blood pressure.

Better Diet Quality during Pregnancy Is Associated with a Reduced Likelihood of an Infant Born Small for Gestational Age: An Analysis of the Prospective New Hampshire Birth Cohort Study

Background

Birth weight has a U-shaped relation with chronic disease. Diet quality during pregnancy may impact fetal growth and infant birth weight, yet findings are inconclusive.

Objective

We examined the relation between maternal diet quality during pregnancy and infant birth size among women enrolled in a prospective birth cohort.

Methods

Women 18-45 y old with a singleton pregnancy were recruited at 24-28 wk of gestation from prenatal clinics in New Hampshire. Women completed a validated food frequency questionnaire at enrollment. Diet quality was computed as adherence to the Alternative Healthy Eating Index. Infant birth outcomes (sex, head circumference, weight, and length) were extracted from medical records. Weight-for-length z scores, low birth weight, macrosomia, and size for gestational age [small for gestational age (SGA) or large for gestational age (LGA)] were computed. Multivariable regression models fit each outcome on quartiles of diet quality, adjusted for covariates. Models were computed overall and stratified by smoking status.

Results

Analyses included 862 women and infants with complete data. Lower diet quality was associated with lower maternal education, being a smoker, prepregnancy obesity status, and lack of exercise during pregnancy. Overall, 3.4% of infants were born with a low birth weight, 12.1% with macrosomia, 4.6% were SGA, and 8.7% were LGA. In an adjusted model, increased diet quality appeared linearly associated with a reduced likelihood of SGA (P-trend = 0.03), although each quartile comparison did not reach statistical significance. Specifically, ORs for SGA were 0.89 (95% CI: 0.37, 2.15), 0.73 (95% CI: 0.28, 1.89), and 0.35 (95% CI: 0.11, 1.08) for each increasing quartile of diet quality compared to the lowest quartile. Similar trends for SGA were observed among non-smokers (n = 756; P-trend = 0.07). Also among non-smokers, increased diet quality was associated with lower infant birth weight (P-trend = 0.03) and a suggested reduction in macrosomia (P-trend = 0.07).

Conclusions

Increased diet quality during pregnancy was related to a reduced risk of SGA in this cohort of pregnant women from New Hampshire. Additional studies are needed to elucidate the relation between maternal diet quality and macrosomia.

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.

Systematic review and meta-analysis of preterm birth and later systolic blood pressure

Lower birth weight because of fetal growth restriction is associated with higher blood pressure later in life, but the extent to which preterm birth (<37 completed weeks' gestation) or very low birth weight (<1500 g) predicts higher blood pressure is less clear. We performed a systematic review of 27 observational studies that compared the resting or ambulatory systolic blood pressure or diagnosis of hypertension among children, adolescents, and adults born preterm or very low birth weight with those born at term. We performed a meta-analysis with the subset of 10 studies that reported the resting systolic blood pressure difference in millimeters of mercury with 95% CIs or SEs. We assessed methodologic quality with a modified Newcastle-Ottawa Scale. The 10 studies were composed of 1342 preterm or very low birth weight and 1738 term participants from 8 countries. The mean gestational age at birth of the preterm participants was 30.2 weeks (range: 28.8-34.1 weeks), birth weight was 1280 g (range: 1098-1958 g), and age at systolic blood pressure measurement was 17.8 years (range: 6.3-22.4 years). Former preterm or very low birth weight infants had higher systolic blood pressure than term infants (pooled estimate: 2.5 mm Hg [95% CI: 1.7-3.3 mm Hg]). For the 5 highest quality studies, the systolic blood pressure difference was slightly greater, at 3.8 mm Hg (95% CI: 2.6-5.0 mm Hg). We conclude that infants who are born preterm or very low birth weight have modestly higher systolic blood pressure later in life and may be at increased risk for developing hypertension and its sequelae.

Lifecourse socioeconomic trajectories and C-reactive protein levels in young adults: findings from a Brazilian birth cohort

Socioeconomic factors are associated with cardiovascular disease. C-reactive protein (CRP) is increasingly implicated as a candidate linking conventional risk factors and atherosclerosis. The impact of early- and later-life socioeconomic status (SES) on CRP levels has not been widely investigated and a handful of studies from high-income countries are inconsistent. We set out to examine the associations between lifecourse socioeconomic indicators (family income at birth, maternal education, family income at age 23 and own education) on CRP levels in young adults belonging to the 1982 Pelotas (Brazil) Birth Cohort Study (n = 5914). Early-life SES showed significant and graded associations with CRP levels at age 23 independently of later SES. For example, men with higher family income at birth showed higher CRP levels at age 23 (p = 0.001 for trend) and women with less educated mothers showed higher CRP levels (p = 0.01 for trend). Notably, differential directions of association between SES indicators and CRP levels between men and women were found. When adjusted for SES at age 23, men with the lowest family income at birth showed 42% lower CRP levels when compared to men in the highest family income group (−42; 95% CI: -60,-16). In contrast women born to the least educated mothers had the highest CRP levels (35; 95% CI -2, 86). In both sexes, adiposity accounted for the overwhelming majority of the associations between SES and CRP levels. Sex and gender roles specific to middle-income countries, socio-cultural and environmental conditions that may impact adiposity, and the level of epidemiological transition may be key factors that are linked to the associations between lifecourse SES and CRP levels. Public health strategies aimed at decreasing the burden of cardiovascular disease in middle-income settings, in addition to highlighting the risks associated with adult obesity, should not overlook the wide-ranging impacts of lifecourse social determinants.

Very preterm birth is a risk factor for increased systolic blood pressure at a young adult age

Children born very prematurely who show intrauterine growth retardation (IUGR) are suggested to be at risk of developing high blood pressure as adults. Renal function may already be impaired by young adult age. To study whether very preterm birth affects blood pressure in young adults, we measured 24-h ambulatory blood pressure (Spacelabs 90207 device) and renin concentration in 50 very premature individuals (<32 weeks of gestation), either small (SGA) or appropriate (AGA) for gestational age (21 SGA, 29 AGA), and 30 full-term controls who all were aged 20 years at time of measurement. The mean (standard deviation) daytime systolic blood pressure in SGA and AGA prematurely born individuals, respectively, was 122.7 (8.7) and 123.1 (8.5) mmHg. These values were, respectively, 3.6 mmHg [95% confidence interval (CI) -0.9 to 8.0] and 4.2 mmHg (95% CI 0.4-8.0) higher than in controls [119.6 (7.6)]. Daytime diastolic blood pressure and nighttime blood pressure did not differ between groups. We conclude that individuals born very preterm have higher daytime systolic blood pressure and higher risk of hypertension at a young adult age.

Epidemiology of early and late growth in height, leg and trunk length: findings from a birth cohort of Brazilian males

BACKGROUND/OBJECTIVE

To investigate socioeconomic, gestational and early life exposures as potential determinants of total height, leg and trunk length.

SUBJECTS/METHODS

Male subjects from the 1982 Pelotas Birth Cohort Study were examined in 1986 at home, and in 2000 when registering at the local army base. The follow-up rate was 79%. Standing and sitting heights were measured on both occasions. Leg length was calculated as the difference between standing and sitting heights. Outcome measures were height, leg and trunk length at 4 and 18 years and growth in this period. Complete data were obtained for 2012 participants, representing 71% of all eligible male subjects.

RESULTS

Mean (s.d.) height, trunk length and leg length at 18 years were 173.4 (6.8), 96.0 (3.5) and 77.5 cm (4.5), respectively. The mean (s.d.) change in height from 1986 to 2000 was 75.4 cm (5.2) and for leg and trunk length 35.4 (3.9) and 40.0 cm (2.9), respectively. Of 11 independent variables analyzed, only maternal height and birthweight were associated with all three variables of growth. Gestational age showed no associations with growth or attained size.

CONCLUSIONS

Early growth plays a pivotal role in determining attained height and its components. Both biological and socioeconomic variables strongly influence determinants of height, though socioeconomic factors appear to be more important in early growth. Leg and trunk length contribute almost equally to differences in overall height, regardless of the independent variable influencing the difference. Public health strategies designed to improve chronic disease profiles should focus on the early growth period.

[Hypertension associated factors and blood pressure among adolescent workers]

The aim of this study was to identify hypertension associated factors (AF) and verify blood pressure (BP) levels among adolescent workers. Interviews were conducted with 193 working adolescents--135 men and 58 women between 16 and 18 years. After five minutes in seated position, their arm circumferences were measured and their BP was determined using correct (CCW) and standard (SCW) cuff widths. The values were related to AF. BP was, in average, 105.2/60.9 mmHg (CCW) and 101.0/57.9 (SCW- p < 0.05). Among the AF found, only skin color and alcoholic drinking were associated to BP elevation, also noted in male adolescents. When using CCW, more hypertensive and borderline adolescents were found than using SCW. All of them had at least one AF. It can be concluded that there are several hypertension AF among this population, and some of them are already causing BP elevation. Studies such as this should be made frequently because adolescent blood pressure levels can predict hypertension in adulthood.

Hb A1c in relation to intrauterine growth among male adolescents in southern Brazil

The fetal origins hypothesis states that nutritional deprivation in utero affects fetal development and contributes to the incidence of diseases associated with the metabolic syndrome in later life. This study investigated whether haemoglobin (Hb) A(1c), an indicator of blood glucose, varied among healthy male adolescents according to their fetal growth rate, in a middle-income setting. Participants were men aged 18 years, belonging to the 1982 Pelotas birth cohort. Complete data, including gestational age and Hb A(1c) at age 18 years, were available for 197 individuals. There was an inverse association between mean Hb A(1c) and birthweight for the gestational age, but not birthweight alone. The association remained significant after adjustment for family income and mother's education, as well as for body mass index at 18 years (P for trend=0.01 and 0.03, respectively).

The association between intrauterine growth restriction in the full-term infant and high blood pressure at age 7 years: results from the Collaborative Perinatal Project

OBJECTIVE

To use neonatal and placental anthropometry as proxy measures of intrauterine growth restriction (IUGR) and to relate these to blood pressure later in childhood.

STUDY DESIGN

A post hoc analysis of full-term white and black children from the Collaborative Perinatal Project, followed from birth until age 7 years (n = 29,710). Blood pressure above the 90th percentile by gender and race was considered high blood pressure. Anthropometric measures at birth included birth weight, ponderal index (PI, birth weight/birth length(3)), head to chest circumference (HCC) ratio, and placental ratio percentage (PRP, placental weight(*)100/birth weight).

RESULTS

Among anthropometric measures, PI, HCC, and birth weight were not associated with high systolic blood pressure at age 7 years, but PRP was. In multiple logistic regression, high systolic blood pressure and widened pulse pressure were both predicted by increased PRP [odds ratio (OR) 1.03 and 1.04, P < 0.001] but not by birth weight, when adjusted for gender, race, and maternal education. High diastolic blood pressure was weakly predicted by birth weight (OR 1.10, P = 0.05) but not by PRP.

CONCLUSIONS

PRP is associated with an increased risk for high systolic blood pressure and pulse pressure later in childhood, whereas birth weight, PI, and HCC are not. The proportion of placental weight to birth weight is a useful marker of IUGR for studying the developmental origins of adult disease hypothesis.

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 Pelotas birth cohort study, Rio Grande do Sul, Brazil, 1982-2001

Given the growing recognition of the importance of the life course approach for the determination of chronic diseases, birth cohort studies are becoming increasingly important. This paper describes the methods used in the 1982 Pelotas (Brazil) birth cohort study, one of the largest and longest studies of this type in developing countries. All 5,914 hospital births occurring in Pelotas in 1982 (over 99% of all deliveries) were studied prospectively. The main stages of the study took place in 1983, 1984, 1986, 1995, 1997, 2000, and 2001. More than two thousand variables are available for each subject who participated in all stages of the study. Recent phases of the study included the examination of 2,250 males when presenting for the army recruitment exam in 2000, the study of a 27% sample of men and women in 2001 through household visits, and the study of over 400 children born to the cohort women. Follow-up rates in the recent stages of the cohort were 78.9% for the army examination and 69.0% for the household visits. Ethnographic and oral health studies were conducted in sub-samples. Some recent results on blood pressure, adolescent pregnancy, and asthma are presented as examples of utilization of the data. Suggestions on lessons learned for other cohort studies are proposed.

Birth size, early childhood growth, and adolescent obesity in a Brazilian birth cohort

DESIGN

Cross-sectional visit to a subsample of a population-based birth cohort.

SAMPLE

A total of 1076 adolescents aged 14-16 y; 51% males.

MEASUREMENTS

Weight, height, subscapular and triceps skinfolds were used for assessing overweight and obesity in adolescence, using WHO-recommended criteria. Anthropometric status in early life was measured through birthweight and through weight and length/height at average ages of 20 and 43 months.

RESULTS

All analyses were adjusted for socioeconomic and maternal confounding factors. Birthweight and attained size (Z-scores of weight-for-age, height-for-age and weight-for-height) at 20 and 43 months were associated linearly and positively with overweight and obesity in adolescence. Four in each five obese adolescents were not overweight in childhood. Rapid weight gain, both between birth and 20 months, and between 20 and 43 months, was also associated with adolescent overweight and with obesity. Rapid height gain between 20 and 43 months was associated with overweight only. Most associations were stronger for boys.

CONCLUSIONS

Birth size, attained size in childhood and particularly growth velocity in early life were associated with increased prevalence of obesity and overweight in Brazilian adolescents. On the other hand, the vast majority of overweight or obese adolescents were not overweight children. Early interventions are undoubtedly important, but population-based strategies aimed at improving diets and physical activity appear to have greater long-term potential than measures targeted at overweight children.

Consumo alimentar de adolescentes com e sem sobrepeso do Município do Rio de Janeiro

Comparam-se, neste estudo, as características do consumo alimentar de uma amostra probabilística de adolescentes com sobrepeso e adolescentes com peso normal, com idades entre 12 e 17,9 anos. Os dados analisados foram obtidos em pesquisa realizada no Município do Rio de Janeiro, em 1995-1996. Estimou-se o consumo alimentar através de um questionário de freqüência do consumo de alimentos semiquantitativo. Avaliou-se o estado nutricional através do índice de massa corporal (IMC = peso/altura²), classificando-se os adolescentes com e sem sobrepeso pelo percentil 90 da distribuição do IMC de crianças brasileiras de 1989. O consumo de indivíduos com e sem sobrepeso foi semelhante, em ambos os grupos observou-se consumo inferior ao mínimo das porções recomendadas dos grupos alimentares e consumo elevado de alimentos de alta densidade energética. Esses hábitos alimentares propiciam o desenvolvimento de excesso de peso e podem ser determinantes de obesidade e doenças crônicas não transmissíveis na maturidade.

Early and late growth and blood pressure in adolescence

OBJECTIVE

To assess the effect of growth during infancy and childhood on blood pressure in adolescence.

DESIGN

Birth cohort study.

SETTING

Pelotas, southern Brazil.

PARTICIPANTS

749 adolescents with complete information on birth weight and gestational age, as well as on anthropometric data at all three follow up visits (mean age 20 months, 42 months, and 15 years).

MAIN OUTCOME MEASUREMENTS

Systolic and diastolic blood pressure at adolescence.

RESULTS

After controlling for possible confounding variables, birth weight was negatively associated with systolic blood pressure, one unit increase in standard deviation score of birth weight for gestational age was associated with a decrease of 1.23 mm Hg (95% confidence intervals -2.03 to -0.43) in systolic blood pressure. Weight for age z score at the age of 15 years showed a strong positive association with systolic blood pressure, one unit increase in standard deviation score of birth weight for gestational age was associated with an increase of 4.4 mm Hg (95% confidence intervals 3.50 to 5.3). Diastolic blood pressure was not associated with birth weight. For adequate for gestational age infants, the positive association between weight in adolescence and blood pressure became stronger when previous weights were added to the model.

CONCLUSION

This study showed that early--as well as--late catch up growth is associated with increased systolic blood pressure in adolescence, whereas only late catch up is related with diastolic blood pressure. These findings suggest that catch up growth, irrespective of age, is associated with increased blood pressure in adolescence.

Cardiovascular disease risk factors are related to adult adiposity but not birth weight in young guatemalan adults

Fetal undernutrition has been hypothesized to program inappropriate metabolic responses to nutritional abundance in later life. Most studies have been conducted in industrialized countries. We studied the relationship between birth weight and risk factors for cardiovascular disease (CVD) among 187 men and 198 women age 20-29 y (mean age 24 y) who had participated in a longitudinal study conducted in Guatemala between 1969 and 1977. In women, birth weight was positively associated with adult body mass index (BMI; P < 0.01), systolic (P < 0.001) and diastolic blood pressure (P < 0.05), but not with glucose or any lipid measure. In men, birth weight was not associated with adult BMI, blood pressure or glucose, and was weakly and inversely related to total cholesterol and LDL cholesterol (test for trend: P = 0.06 and P = 0.09, respectively). Adult BMI was associated with increased prevalence of CVD risk factors in both men and women. Our data offer no support for the fetal programming of cardiovascular disease risk hypothesis in young adult women, and weak support in young adult men. Overweight in adults is a strong determinant of variance in CVD risk factor prevalence.

[Epidemiological research trends in chronic diseases]

Identification of adult risk factors has contributed to a decrease in the occurrence of cardiovascular diseases and some types of cancer, particularly in developed countries. However, the prevailing etiologic model emphasizes risk factors associated with life style and occupational exposures. This emphasis leads to an excessive individualization of risk, weakening the link between epidemiology and public health. This article comments on the opinions of epidemiologists concerning the failures, limitations, and evolution of modern epidemiology that have helped redirect the field's theoretical underpinnings. Alternatives to the current model tend to integrate findings from molecular biology with classic risk factors and early adverse conditions in life, taking into account all these causal influences in hierarchical levels of organization. The author identifies and comments on three important approaches in this evolution: molecular epidemiology, the theory of early life factors, and multilevel models.

[Diagnosis of overweight in adolescents: comparative study of the performance different criteria for body mass index]

OBJECTIVE

In an attempt to simplify the screening process for detecting obesity in adolescence, the performance of different cutoff values for body mass index (BMI) was assessed in a population-based cohort in Southern Brazil.

METHODS

A total of 493 adolescents aged 15-16 years who lived in the city of Pelotas, Brazil, were studied. Obesity was defined according to the WHO criteria taking into account age and sex (a BMI equal to or greater than the 85th percentile of the NHANES I reference, plus subscapular and triceps skinfold equal to or greater than the 90th percentile of the same reference). Different BMI cutoff values were used to assess their specificity and sensitivity.

RESULTS

For boys, BMI>/=25 kg/m(2) showed the best performance for detecting obesity, with a sensitivity of 90% and only 5% of false positives. The Brazilian proposed criteria that was used had 100% sensitivity but up to 23% of false positives. Higher cutoff values were also tested, but there was a slight increase in specificity, accompanied by a marked reduction in sensitivity.

CONCLUSIONS

The BMI cutoff of 25 kg/m(2) presented the best performance for screening obesity in the studied sample, and it is recommended for adolescents aged 15 and more in populations with similar characteristics. It provides a single cutoff value to be used in primary health services, eliminating the need for age and sex-specific values and skinfold measurements, and it is also consistent with the cutoff value proposed to identifying overweight adults.