Childhood socioeconomic position, adult socioeconomic position and social mobility in relation to markers of adiposity in early adulthood: evidence of differential effects by gender in the 1978/79 Ribeirao Preto cohort study.

BACKGROUND: Longitudinal studies drawn from high-income countries demonstrate long-term associations of early childhood socioeconomic deprivation with increased adiposity in adulthood. However, there are very few data from resource-poor countries where there are reasons to anticipate different gradients. Accordingly, we sought to characterise the nature of the socioeconomic status (SES)-adiposity association in Brazil. METHODS: We use data from the Ribeirao Preto Cohort Study in Brazil in which 9067 newborns were recruited via their mothers in 1978/79 and one-in-three followed up in 2002/04 (23-25years). SES, based on family income (salaries, interest on savings, pensions and so on), was assessed at birth and early adulthood, and three different adiposity measures (body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR)) ascertained at follow-up. The association between childhood SES, adult SES and social mobility (defined as four permutations of SES in childhood and adulthood: low-low, low-high, high-low, high-high), and the adiposity measures was examined using linear regression. RESULTS: There was evidence that the association between SES and the three markers of adiposity was modified by gender in both adulthood (P<0.02 for all outcomes) and childhood SES (P<0.02 for WC and WHR). Thus, in an unadjusted model, linear regression analyses showed that higher childhood SES was associated with lower adiposity in women (coefficient (95% confidence intervals) BMI: -1.49 (-2.29,-0.69); WC: -3.85 (-5.73,-1.97); WHR: -0.03 (-0.04,-0.02)). However, in men, higher childhood SES was related to higher adiposity (BMI: 1.03 (0.28,-1.78); WC: 3.15 (1.20, 5.09); WHR: 0.009 (-0.001, 0.019)) although statistical significance was not seen in all analyses. There was a suggestion that adult SES (but not adult health behaviours or birthweight) accounted for these relationships in women only. Upward mobility was associated with protection against greater adiposity in women but not men. CONCLUSION: In the present study, in men there was some evidence that both higher childhood and adulthood SES was related to a higher adiposity risk, while the reverse gradient was apparent in women.

Maternal age and low birth weight: a reinterpretation of their association under a demographic transition in southern Brazil.

To evaluate the relationship between changes in fecundity rates and maternal age and the impact of maternal age on low birth weight (LBW) rates in a developed region in southern Brazil. A time series study evaluating birth weight and maternal ages through the born alive information system (SINASC) in Porto Alegre from 1996 to 2008. The Chi-square test for trends was used to evaluate the trend of LBW and fecundity rates at each maternal age. Population attributed risk (PAR) was used to calculate the impact of maternal age on LBW rates. The study included 271,100 newborns. There was a significant reduction in fecundity rates in all age groups younger than 34 years, but especially in the groups between 20 and 29 years. Overall LBW increased from 9.3 to 10.7 % (P < 0.001). The PAR for LBW showed a reduction in the group from 17 to 19 years (from 1.7 % in 1996-1999 to 0.1 % in 2004-2008), and an increase in the groups from 35 to 39 years (from 2.0 % in 1996-1999 to 2.3 % in 2004-2008) and above 40 (from 1.1 % in 1996-1999 to 1.5 % in 2004-2008). There was a significant change in fecundity pattern in the last 12 years in southern Brazil. Adolescent mothers were surpassed by mothers over 30 years of age in terms of vulnerability for LBW babies. The results show a change in the maternal age distribution towards older mothers, accompanied by an increasing incidence of LBW. This demographic transition also involved a paradoxical pattern with a remarkable reduction in fecundity rates in intermediate maternal age groups with concomitant increase in their risk for LBW.

Do early life factors influence body mass index in adolescents?

The association between early life factors and body mass index (BMI) in adulthood has been demonstrated in developed countries. The aim of the present study was to assess the influence of early life factors (birth weight, gestational age, maternal smoking, and social class) on BMI in young adulthood with adjustment for adult socioeconomic position. A cohort study was carried out in 1978/79 with 6827 mother-child pairs from Ribeirão Preto city, located in the most developed economic area of the country. Biological, economic and social variables and newborn anthropometric measurements were obtained shortly after delivery. In 1996, 1189 males from this cohort, 34.3% of the original male population, were submitted to anthropometric measurements and were asked about their current schooling on the occasion of army recruitment. A multiple linear regression model was applied to determine variables associated with BMI. Mean BMI was 22.7 (95%CI = 22.5-23.0). After adjustment, BMI was 1.22 kg/m(2) higher among infants born with high birth weight ( > or = 4000 g), 1.21 kg/m(2) higher among individuals of low social class at birth and 0.69 kg/m(2) higher among individuals whose mothers smoked during pregnancy (P < 0.05). The association between social class at birth and BMI remained statistically significant (P < 0.05) even after adjustment for adult schooling. These findings suggest that early life social influences on BMI were more important and were not reversed by late socioeconomic position. Therefore, prevention of overweight and obesity should focus not only on changes in adult life styles but also on factors such as high birth weight.

Do intrauterine growth restriction and overweight at primary school age increase the risk of elevated body mass index in young adults?

Obesity is one of the rising public health problems characterized as a risk factor for many chronic diseases in adulthood. Early life events such as intrauterine growth restriction, as well as life style, are associated with an increased prevalence of this disease. The present study was performed to determine if intrauterine growth restriction interacts with overweight at primary school age to affect body mass index (BMI) in young adults. From June 1, 1978 to May 31, 1979, 6827 singleton liveborns from Ribeirão Preto, São Paulo State, Brazil, corresponding to 98% of all births at the 8 maternity hospitals, were examined and their mothers were interviewed. Samples from the initial cohort were examined again at primary school age (8 to 11 years of age) and at the time of military service (18 years of age). There were 519 male individuals with complete measurements taken in the three surveys. Intrauterine growth-restricted individuals had a BMI 0.68 kg/m(2) lower than that of individuals who were not restricted (95%CI = -1.34 to -0.03) and overweight at primary school age showed a positive and strong effect on BMI at 18 years of age (coefficient 5.03, 95%CI = 4.27 to 5.79). However, the increase in BMI was much higher--6.90 kg/m(2)--when the conscript had been born with intrauterine growth restriction and presented overweight at primary school age (95%CI = 4.55 to 9.26). These findings indicate that the effect of intrauterine growth restriction on BMI at 18 years of age is modified by later weight gain during school age.

Profile of three Brazilian birth cohort studies in Ribeirão Preto, SP and São Luís, MA.

We describe three birth cohort studies, respectively carried out in 1978/79 and 1994 in Ribeirão Preto, a city located in the most developed region of Brazil, and in 1997/98 in São Luís, a city located in a less developed region. The objective of the present report was to describe the methods used in these three studies, presenting their history, methodological design, objectives, developments, and difficulties faced along 28 years of research. The first Ribeirão Preto study, initially perinatal, later encompassed questions regarding the repercussions of intrauterine development on future growth and chronic adult diseases. The subjects were evaluated at birth (N = 6827), at school age (N = 2861), at the time of recruitment for military service (N = 2048), and at 23/25 years of age (N = 2063). The study of the second cohort, which started in 1994 (N = 2846), permitted comparison of aspects of perinatal health between the two groups in the same region, such as birth weight, mortality and health care use. In 1997/98, a new birth cohort study was started in São Luís (N = 2443), capital of the State of Maranhão. The 1994 Ribeirão Preto cohort and the São Luís cohort are in the second phase of joint follow-up. These studies permit comparative temporal analyses in the same place (Ribeirão Preto 1978/79 and 1994) and comparisons of two contrasting populations regarding cultural, economic and sociodemographic conditions (Ribeirão Preto and São Luís).

Hypertensive disorders during pregnancy and health outcomes in the offspring: a systematic review.

UNLABELLED: The hypertensive disorders of pregnancy complicate up to 10% of pregnancies worldwide and are a leading cause of maternal, foetal, and neonatal morbidity and mortality. The aim of this study was to present an overview of recent studies addressing offspring's medium and long-term health outcomes after intrauterine exposure to maternal hypertension. A search on PubMed/MEDLINE and Bireme databases was conducted to identify observational studies that reported any offspring outcome measured after the 6th month of life. The search was limited to studies published after May 2008. Forty-five articles were included and categorized into four groups of outcomes: cardiovascular, immune, metabolic and behavioural/neurological effects. According to our findings, hypertensive disorders of pregnancy had an overall negative impact on offspring's cardiovascular, immune and neurological health, although not all parameters analysed in each group had consistent results among studies. The most prominent and reliable associations were verified between gestational hypertension and higher offspring's blood pressure and between preeclampsia and offspring's lower cognitive functioning. In the metabolic outcomes, body composition had conflicting results among papers, while all studies that examined blood biomarkers showed no evidence that preeclampsia or gestational hypertension could be associated with an alteration of this metabolic outcomes. Most included studies were highly heterogeneous regarding the measure of outcomes and covariables used for adjustments. Future studies should consider using the same protocols and cut-off points already published so that results can be better compared and summarized. This review was registered in PROSPERO. REGISTRATION NUMBER: CRD42015020838.

Early life trauma is associated with decreased peripheral levels of thyroid-hormone T3 in adolescents.

An adverse early life environment can induce changes on behavioral and metabolic responses later in life. Recent studies in rats showed that the quality of maternal care as measured by high levels of pup licking and grooming (LG) was associated with changes in the relationship between the precursor thyroid-hormone T4 and the more active T3. Here we investigated if early exposure to childhood abuse is associated with thyroid-hormone levels in human adolescents. Given the empirical evidence from animal models showing that good maternal care was associated with increased conversion of T4 to T3, we hypothesized that early adversity would be associated with a decreased peripheral conversion of T4 to T3. A sample of 80 adolescents (10-18 years) participated in this study. We used the Childhood Trauma Questionnaire to investigate early life stress. We calculate the body mass index (BMI) assessing weight and height and sexual maturation stage was determined by self-assessment. Blood samples were collected to measure T3 and T4 levels. ANCOVA were used to evaluate the influence of the Physical Abuse domain of the Childhood Trauma Questionnaire as the early life stress variable in T3 and T4 separately, adjusted for potential confounders such as pubertal status, gender, socioeconomic status and BMI. Early life trauma was associated with reduced T3 levels in adolescents, when adjusted for potential confounders (p=0.013), but not with peripheral T4 levels (p=0.625). We extended findings from animal models showing that adverse early experience persistently impacts on the individual's responses to stress, which is marked by an abnormal metabolism of thyroid hormones. Further studies are needed to further investigate the nature of such associations.

Litter size reduction alters insulin signaling in the ventral tegmental area and influences dopamine-related behaviors in adult rats.

Postnatal overfeeding is a well-known model of early-life induced obesity and glucose intolerance in rats. However, little is known about its impact on insulin signaling in specific brain regions such as the mesocorticolimbic system, and its putative effects on dopamine-related hedonic food intake in adulthood. For this study, rat litters were standardized to 4 (small litter - SL) or 8 pups (control - NL) at postnatal day 1. Weaning was at day 21, and all tests were conducted after day 60 of life in male rats. In Experiment 1, we demonstrated that the SL animals were heavier than the NL at all time points and had decreased AKT/pAKT ratio in the Ventral Tegmental Area (VTA), without differences in the skeletal muscle insulin signaling in response to insulin injection. In Experiment 2, the standard rat chow intake was addressed using an automated system (BioDAQ, Research Diets(®)), and showed no differences between the groups. On the other hand, the SL animals ingested more sweet food in response to the 1 min tail-pinch challenge and did not develop conditioned place preference to sweet food. In Experiment 3 we showed that the SL rats had increased VTA TH content but had no difference in this protein in response to a sweet food challenge, as the NL had. The SL rats also showed decreased levels of dopamine D2 receptors in the nucleus accumbens. Here we showed that early postnatal overfeeding was linked to an altered functioning of the mesolimbic dopamine pathway, which was associated with altered insulin signaling in the VTA, suggesting increased sensitivity, and expression of important proteins of the dopaminergic system.

Detection of inborn errors of metabolism in unselected patients from pediatric intensive care units in Porto Alegre, Brazil: evaluation of screening techniques.

1. The present study provides an analysis of the interpretation and usefulness of mass biochemical urine screening tests currently applied to a population of severely ill children consisting of 232 unselected individuals, under various medications, held in intensive care units. 2. Testing for glycosaminoglycans by the cetyltrimethylammonium bromide reaction is of little benefit to this population. The Ehrlich reaction, used to detect porphobilinogen, should be reserved for cases which present clinical symptoms. Owing to the large number of false-positives and because chromatography or electrophoresis can easily be used to detect tyrosine, it is suggested that the nitrosonaphthol test be abandoned. The cyanide nitroprusside reaction should be used when chromatography or electrophoresis suggests cystinuria, homocystinuria or beta-mercapto lactate disulfiduria. 3. Because of its high sensitivity in detecting reducing substances, the Clinitest is useful for selecting samples to be investigated further by sugar chromatography. 4. Given the relatively high frequency of organic acidurias, particularly methylmalonic aciduria, in intensive care unit populations, it is suggested that the p-nitroaniline reaction be incorporated into the battery of chemical urine tests. 5. A comparison between paper chromatography and high voltage paper electrophoresis in terms of effective analysis of amino acid patterns demonstrated that chromatography is preferential, since this is as sensitive as electrophoresis, does not require a special apparatus and permits the simultaneous use of plasma and urine from the same patient, thus facilitating the interpretation of amino acid patterns.

Maternal age, social changes, and pregnancy outcome in Ribeirão Preto, southeast Brazil, in 1978-79 and 1994.

This study focused on changes in demographic, social, and health-care patterns and pregnancy outcome related to maternal age from 1978-79 to 1994 in Ribeirão Preto, São Paulo State, Brazil. Information on pregnancy outcome was obtained from two cohorts of singleton live births, 6,681 births in 1978/79 and 2,839 births in 1994. A standardized questionnaire was submitted to mothers after delivery, and demographic information was collected from official records. There was a significant increase in teenage pregnancies (from 5.1% to 7.4%) and a decrease in infant mortality (36/1,000 to 17/1,000). There were significant decreases in the proportion of mothers with low schooling (24.5% to 14.4%), smoking (28.9% to 21.%), and multiparity (14.7% to 9.0%). Prenatal coverage improved (from 23.4% to 9.0% of patients with fewer than 4 prenatal visits), while cesareans increased (from 30.6% to 50.8%), as did preterm delivery (7.2% to 13.6%) and low birthweight (7.2% to 10.6%). Despite significant improvements in some maternal characteristics, the proportion of teenage pregnancies, preterm deliveries, low birthweight, and cesareans increased, raising concerns about the health costs and consequences for mothers and infants.

Infant mortality rates according to socioeconomic status in a Brazilian city.

OBJECTIVE: Data from municipal databases can be used to plan interventions aimed at reducing inequities in health care. The objective of the study was to determine the distribution of infant mortality according to an urban geoeconomic classification using routinely collected municipal data. METHODS: All live births (total of 42,381) and infant deaths (total of 731) that occurred between 1994 and 1998 in Ribeirão Preto, Brazil, were considered. Four different geoeconomic areas were defined according to the family head's income in each administrative urban zone. RESULTS: The trends for infant mortality rate and its different components, neonatal mortality rate and post-neonatal mortality rate, decreased in Ribeirão Preto from 1994 to 1998 (chi-square for trend, p<0.05). These rates were inversely correlated with the distribution of lower salaries in the geoeconomic areas (less than 5 minimum wages per family head), in particular the post-neonatal mortality rate (chi-square for trend, p<0.05). Finally, the poor area showed a steady increase in excess infant mortality. CONCLUSIONS: The results indicate that infant mortality rates are associated with social inequality and can be monitored using municipal databases. The findings also suggest an increase in the impact of social inequality on infant health in Ribeirão Preto, especially in the poor area. The monitoring of health inequalities using municipal databases may be an increasingly more useful tool given the continuous decentralization of health management at the municipal level in Brazil.

[Perinatal health: methodology and characteristics of the studied population]. / Saúde perinatal: metodologia e características da população estudada.

OBJECTIVE: To describe the methodological procedures and some sociodemographic and medical care characteristics of the population studied in a research project on perinatal health developed in the Ribeirão Preto county, SP, in 1994, in order to make historical comparisons with the indicators of mother-child health of a similar study conducted 15 years before in the same municipality. MATERIAL AND METHOD: All the hospital births that occurred in Ribeirão Preto from June 1978 to May 1979 were studied by interviewing the mothers and obtaining data about maternal and paternal habits, social situation of the family, medical care during pregnancy and delivery, duration of pregnancy, and anthropometric and mortality data about the newborn children. A new study was conducted in 1994 using the same methodology to collect data about a sample of 1/3 of the births that had occurred in the municipality in that year (all the hospital births observed during a period of 4 months), and also about the mortality of this group up to one year after the termination of birth data collection. The interviews were held after delivery and infant weight and length were measured immediately after birth. Infant mortality was evaluated by surveying the data referring to all deaths of infants born during the year of the study and up to 1 year after its termination. The data were obtained from the Municipal Health Secretariat to which copies of all death certificates emitted in the registry offices of the county are sent obligatorily. RESULTS: An investigation was made into 3,663 births, 3,579 of which were singletons; of these, 2,846 were from the municipality. Comparison with the data obtained in the previous study showed an increase in the frequency of some indicators such as adolescent mothers, prematurity, low birth weight and cesarian section; on the other hand, there was a 50% decrease in the mortality rate and its components.

Effects of in utero conditions on adult feeding preferences.

The fetal or early origins of adult disease hypothesis states that environmental factors, particularly nutrition, act in early life to program the risks for chronic diseases in adult life. As eating habits can be linked to the development of several diseases including obesity, diabetes and cardiovascular disease, it could be proposed that persistent food preferences across the life-span in people who were exposed to an adverse fetal environment may partially explain their increased risk to develop metabolic disease later in life. In this paper, we grouped the clinical and experimental evidence demonstrating that the fetal environment may impact the individual's food preferences. In addition, we review the feeding preferences development and regulation (homeostatic and hedonic pathways, the role of taste/olfaction and the reward/pleasure), as well as propose mechanisms linking early life conditions to food preferences later in life. We review the evidence suggesting that in utero conditions are associated with the development of specific food preferences, which may be involved in the risk for later disease. This may have implications in terms of public health and primary prevention during early ages.

Associations between parenting behavior and anxiety in a rodent model and a clinical sample: relationship to peripheral BDNF levels.

Adverse early-life environment is associated with anxiety-like behaviors and disorders. Brain-derived neurotrophic factor (BDNF) is sensitive to this environment and could be a marker of underlying brain changes. We aimed at evaluating the development of anxiety-like behaviors in a rat model of early adversity, as well as the possible association with BDNF levels. Similar associations were investigated in a sample of adolescent humans. For the rat study, Wistar rat litters were divided into: early-life stress (ELS, limited access to nesting material) and control groups. Maternal behavior was observed from days 1 to 9 of life and, as adults, rats were subjected to behavioral testing and BDNF measurements in plasma, hippocampus, amygdala and periaqueductal gray. For the human study, 129 adolescents were evaluated for anxiety symptoms and perceived parental care. Serum BDNF levels and the Val66Met polymorphism of the BDNF gene were investigated. We found that ELS dams showed more pure contact, that is, contact with low care and high control, toward pups, and their adult offspring demonstrated higher anxiety-like behaviors and plasma BDNF. Also the pure contact correlated positively with adult peripheral BDNF. Similarly in humans, there was a positive correlation between maternal overprotection and serum BDNF only in Met carriers. We also found negative correlations between maternal warmth and separation anxiety, social phobia and school phobia. Finally, our translational approach revealed that ELS, mediated through variations in maternal care, is associated with anxiety in both rats and humans and increased peripheral BDNF may be marking these phenomena.

Exposure to maternal smoking during fetal life affects food preferences in adulthood independent of the effects of intrauterine growth restriction.

Experimental animal studies have shown that nicotine exposure during gestation alters the expression of fetal hypothalamic neuropeptides involved in the control of appetite. We aimed to determine whether the exposure to maternal smoking during gestation in humans is associated with an altered feeding behavior of the adult offspring. A longitudinal prospective cohort study was conducted including all births from Ribeirão Preto (São Paulo, Brazil) between 1978 and 1979. At 24 years of age, a representative random sample was re-evaluated and divided into groups exposed (n = 424) or not (n = 1586) to maternal smoking during gestation. Feeding behavior was analyzed using a food frequency questionnaire. Covariance analysis was used for continuous data and the χ 2 test for categorical data. Results were adjusted for birth weight ratio, body mass index, gender, physical activity and smoking, as well as maternal and subjects' schooling. Individuals exposed to maternal smoking during gestation ate more carbohydrates than proteins (as per the carbohydrate-to-protein ratio) than non-exposed individuals. There were no differences in the consumption of the macronutrients themselves. We propose that this adverse fetal life event programs the individual's physiology and metabolism persistently, leading to an altered feeding behavior that could contribute to the development of chronic diseases in the long term.

Risk factors for sedentary behavior in young adults: similarities in the inequalities.

Physical activity is a known protective factor, with benefits for both metabolic and psychological aspects of health. Our objective was to verify early and late determinants of physical activity in young adults. A total of 2063 individuals from a birth cohort in Ribeirão Preto, Brazil, were studied at the age of 23-25 years. Poisson regression was performed using three models: (1) early model considering birth weight, gestational age, maternal income, schooling and smoking; (2) late model considering individual's gender, schooling, smoking and body mass index; and (3) combined (early + late) model. Physical activity was evaluated using the International Physical Activity Questionnaire, stratifying the individuals into active or sedentary. The general rate of sedentary behavior in the sample was 49.6%. In the early model, low birth weight (relative risk (RR) = 1.186, confidence interval (95%CI) 1.005-1.399) was a risk factor for sedentary activity. Female gender (RR = 1.379, 95%CI = 1.259-1.511) and poor schooling (RR = 1.126, 95%CI = 1.007-1.259) were associated with sedentary behavior in the late model. In the combined model, only female gender and participant's schooling remained significant. An interaction between birth weight and individual's schooling was found, in which sedentary behavior was more prevalent in individuals born with low birth weight only if they had higher educational levels. Variables of early development and social insertion in later life interact to determine an individual's disposition to practice physical activities. This study may support the theoretical model 'Similarities in the inequalities', in which opposed perinatal backgrounds have the same impact over a health outcome in adulthood when facing unequal social achievement during the life-course.

Influence of intrauterine and extrauterine growth on neurodevelopmental outcome of monozygotic twins.

There have been indications that intrauterine and early extrauterine growth can influence childhood mental and motor function. The objective of the present study was to evaluate the influence of intrauterine growth restriction and early extrauterine head growth on the neurodevelopmental outcome of monozygotic twins. Thirty-six monozygous twin pairs were evaluated at the corrected age of 12 to 42 months. Intrauterine growth restriction was quantified using the fetal growth ratio. The effects of birth weight ratio, head circumference at birth and current head circumference on mental and motor outcomes were estimated using mixed-effect linear regression models. Separate estimates of the between (interpair) and within (intrapair) effects of each measure on development were thus obtained. Neurodevelopment was assessed with the Bayley Scales of Infant Development, 2nd edition, by a psychologist blind to the exposure. A standardized neurological examination was performed by a neuropediatrician who was unaware of the exposures under investigation. After adjustment, birth weight ratio and head circumference at birth were not associated with motor or mental outcomes. Current head circumference was associated with mental but not with motor outcomes. Only the intrapair twin effect was significant. An increase of 1 cm in current head circumference of one twin compared with the other was associated with 3.2 points higher in Mental Developmental Index (95%CI = 1.06-5.32; P < 0.03). Thus, no effect of intrauterine growth was found on cognition and only postnatal head growth was associated with cognition. This effect was not shared by the co-twin.

Influence of intrauterine and extrauterine growth on neurodevelopmental outcome of monozygotic twins

There have been indications that intrauterine and early extrauterine growth can influence childhood mental and motor function. The objective of the present study was to evaluate the influence of intrauterine growth restriction and early extrauterine head growth on the neurodevelopmental outcome of monozygotic twins. Thirty-six monozygous twin pairs were evaluated at the corrected age of 12 to 42 months. Intrauterine growth restriction was quantified using the fetal growth ratio. The effects of birth weight ratio, head circumference at birth and current head circumference on mental and motor outcomes were estimated using mixed-effect linear regression models. Separate estimates of the between (interpair) and within (intrapair) effects of each measure on development were thus obtained. Neurodevelopment was assessed with the Bayley Scales of Infant Development, 2nd edition, by a psychologist blind to the exposure. A standardized neurological examination was performed by a neuropediatrician who was unaware of the exposures under investigation. After adjustment, birth weight ratio and head circumference at birth were not associated with motor or mental outcomes. Current head circumference was associated with mental but not with motor outcomes. Only the intrapair twin effect was significant. An increase of 1 cm in current head circumference of one twin compared with the other was associated with 3.2 points higher in Mental Developmental Index (95 percentCI = 1.06-5.32; P < 0.03). Thus, no effect of intrauterine growth was found on cognition and only postnatal head growth was associated with cognition. This effect was not shared by the co-twin.

Do early life factors influence body mass index in adolescents?

The association between early life factors and body mass index (BMI) in adulthood has been demonstrated in developed countries. The aim of the present study was to assess the influence of early life factors (birth weight, gestational age, maternal smoking, and social class) on BMI in young adulthood with adjustment for adult socioeconomic position. A cohort study was carried out in 1978/79 with 6827 mother-child pairs from Ribeirão Preto city, located in the most developed economic area of the country. Biological, economic and social variables and newborn anthropometric measurements were obtained shortly after delivery. In 1996, 1189 males from this cohort, 34.3 percent of the original male population, were submitted to anthropometric measurements and were asked about their current schooling on the occasion of army recruitment. A multiple linear regression model was applied to determine variables associated with BMI. Mean BMI was 22.7 (95 percentCI = 22.5-23.0). After adjustment, BMI was 1.22 kg/m² higher among infants born with high birth weight (³4000 g), 1.21 kg/m² higher among individuals of low social class at birth and 0.69 kg/m² higher among individuals whose mothers smoked during pregnancy (P < 0.05). The association between social class at birth and BMI remained statistically significant (P < 0.05) even after adjustment for adult schooling. These findings suggest that early life social influences on BMI were more important and were not reversed by late socioeconomic position. Therefore, prevention of overweight and obesity should focus not only on changes in adult life styles but also on factors such as high birth weight.

Do intrauterine growth restriction and overweight at primary school age increase the risk of elevated body mass index in young adults?

Obesity is one of the rising public health problems characterized as a risk factor for many chronic diseases in adulthood. Early life events such as intrauterine growth restriction, as well as life style, are associated with an increased prevalence of this disease. The present study was performed to determine if intrauterine growth restriction interacts with overweight at primary school age to affect body mass index (BMI) in young adults. From June 1, 1978 to May 31, 1979, 6827 singleton liveborns from Ribeirão Preto, São Paulo State, Brazil, corresponding to 98 percent of all births at the 8 maternity hospitals, were examined and their mothers were interviewed. Samples from the initial cohort were examined again at primary school age (8 to 11 years of age) and at the time of military service (18 years of age). There were 519 male individuals with complete measurements taken in the three surveys. Intrauterine growth-restricted individuals had a BMI 0.68 kg/m² lower than that of individuals who were not restricted (95 percentCI = -1.34 to -0.03) and overweight at primary school age showed a positive and strong effect on BMI at 18 years of age (coefficient 5.03, 95 percentCI = 4.27 to 5.79). However, the increase in BMI was much higher - 6.90 kg/m² - when the conscript had been born with intrauterine growth restriction and presented overweight at primary school age (95 percentCI = 4.55 to 9.26). These findings indicate that the effect of intrauterine growth restrictionon BMI at 18 years of age is modified by later weight gain during school age.