Low birth weight and longitudinal trends of cardiovascular risk factor variables from childhood to adolescence: the bogalusa heart study

Protective Effects of Maternal Education against Low Birth Weight Deliveries: Blacks' Diminished Returns

Background

Racial and economic disparities in low birth weight (LBW) deliveries is among the most well-established differences between Blacks and Whites. As LBW is an established risk factor for chronic diseases such as asthma and diabetes, it is particularly important to understand drivers of racial and economic disparities in LBW deliveries in urban areas.

Aims

Built on the Minorities' Diminished Returns framework, which argues that educational attainment generates fewer positive health outcomes for Black than White Americans, we conducted this study with three aims: 1) to test the association between mothers' educational attainment and LBW of babies born in urban areas, 2) to compare Blacks and Whites for the effect of mothers' educational attainment on LBW, and 3) to test whether LBW is predictive of future chronic diseases 15 years later.

Methods

Data came from the Fragile Families and Child Well-being / included a random sample of births in cities larger than 200,000 population. For the aims 1 and 2, we analyzed data of 2,922 births to Black (n = 2,146) or White (n = 776) mothers. For aim 3, we analyzed data of a subsample of 1,604 Black or White newborns who were followed to age 15. The presence or absence of chronic diseases was determined at age 15. Logistic regression was used for data analysis.

Results

Maternal educational attainment was inversely associated with LBW overall. We, however, found a significant interaction between maternal educational attainment and race, suggesting that the inverse association between maternal education and LBW is weaker for Black than White babies. At the same time, LBW increased the odds of chronic disease 15 years later.

Conclusions

Diminished returns of maternal educational attainment contribute to racial disparities in LBW, which in turn contributes to future racial inequalities in chronic diseases in urban settings. That is, smaller protective effects of maternal education on reducing LBW for Black than White children contribute to the high prevalence of chronic diseases among adolescents in urban settings. Health disparities are not just due to racial differences in socioeconomic status but also diminishing returns of socioeconomic status indicators such as education for racial and ethnic minorities. Research should study contextual factors that reduce Blacks' ability to translate their human capital to health outcomes in urban settings.

Association between birth weight and childhood cardiovascular disease risk factors in West Virginia

The reported associations between birth weight and childhood cardiovascular disease (CVD) risk factors have been inconsistent. In this study, we investigated the relationship between birth weight and CVD risk factors at 11 years of age. This study used longitudinally linked data from three cross-sectional datasets (N = 22,136) in West Virginia; analysis was restricted to children born full-term (N = 19,583). The outcome variables included resting blood pressure [systolic blood pressure (SBP), diastolic blood pressure (DBP)] and lipid profile [total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, non-HDL, and triglycerides (TG)]. Multiple regression analyses were performed, adjusting for child's body mass index (BMI), sociodemographics, and lifestyle characteristics. Unadjusted analyses showed a statistically significant association between birth weight and SBP, DBP, HDL, and TG. When adjusted for the child's BMI, the association between birth weight and HDL [b = 0.14 (95% CI: 0.11, 0.18) mg/dl per 1000 g increase] and between birth weight and TG [b = -0.007 (-0.008, -0.005) mg/dl per 1000 g increase] remained statistically significant. In the fully adjusted model, low birth weight was associated with higher LDL, non-HDL, and TGs, and lower HDL levels. The child's current BMI at 11 years of age partially (for HDL, non-HDL, and TG) and fully mediated (for SBP and DBP) the relationship between birth weight and select CVD risk factors. While effects were modest, these risk factors may persist and amplify with age, leading to potentially unfavorable consequences in later adulthood.

The interrelationships of birthweight, inflammation and body composition in healthy adults

BACKGROUND

Lower birthweight is associated with an increased risk of cardiovascular diseases and diabetes. We hypothesized that inflammation and body fat may be potential mediators for these inverse relationships.

MATERIALS AND METHODS

Healthy adults aged 25-41 years were enrolled in a prospective population-based cohort study in the Principality of Liechtenstein. Main exclusion criteria were diabetes, overt cardiovascular disease or a body mass index > 35 kg/m(2) . Birthweight was self-reported by the study participants. White blood cell (WBC) count and high-sensitivity C-reactive protein (hs-CRP) levels were assayed from fresh blood samples. Body composition was determined by bioelectrical impedance analysis. Multivariable linear regression models were constructed to assess the relationships between birthweight, inflammation and body composition.

RESULTS

Our sample consisted of 1774 participants (53·4% females) with a median age of 37 years. Median birthweight was 3355 g. In multivariable models, we found an inverse relationship of birthweight with hs-CRP levels (β -0·010 (95% CI -0·02; -0·002), P = 0·01) and WBC count (β -0·002 (95% CI -0·004; -0·0002), P = 0·03). Additional adjustment for body fat mass attenuated these relationships (β -0·008 (95% CI -0·02; 0·0003), P = 0·06 for hs-CRP levels and (β -0·002 (95% CI -0·004; 0·0006), P = 0·16 for WBC count. Body fat mass itself was strongly associated with birthweight (β -0·06 (95% CI -0·10; -0·03), P < 0·0001).

CONCLUSION

Birthweight is inversely associated with inflammation in adulthood. This relationship may be mediated by an elevated body fat mass among individuals with lower birthweight.

Developmental programming of cardiovascular disease following intrauterine growth restriction: findings utilising a rat model of maternal protein restriction

Over recent years, studies have demonstrated links between risk of cardiovascular disease in adulthood and adverse events that occurred very early in life during fetal development. The concept that there are embryonic and fetal adaptive responses to a sub-optimal intrauterine environment often brought about by poor maternal diet that result in permanent adverse consequences to life-long health is consistent with the definition of "programming". The purpose of this review is to provide an overview of the current knowledge of the effects of intrauterine growth restriction (IUGR) on long-term cardiac structure and function, with particular emphasis on the effects of maternal protein restriction. Much of our recent knowledge has been derived from animal models. We review the current literature of one of the most commonly used models of IUGR (maternal protein restriction in rats), in relation to birth weight and postnatal growth, blood pressure and cardiac structure and function. In doing so, we highlight the complexity of developmental programming, with regards to timing, degree of severity of the insult, genotype and the subsequent postnatal phenotype.

Progression of cardio-metabolic risk factors in subjects born small and large for gestational age

Background

Subjects born small (SGA) and large (LGA) for gestational age have an increased risk of cardio-metabolic alterations already during prepuberty. Nevertheless, the progression of their cardio-metabolic profile from childhood to adolescence has not been fully explored. Our aim was to assess potential changes in the cardio-metabolic profile from childhood to adolescence in subjects born SGA and LGA compared to those born appropriate (AGA) for gestational age.

Methods

This longitudinal study included 35 AGA, 24 SGA and 31 LGA subjects evaluated during childhood (mean age (±SD) 8.4±1.4 yr) and then re-assessed during adolescence (mean age 13.3±1.8 yr). BMI, blood pressure, insulin resistance (fasting insulin, HOMA-IR) and lipids were assessed. A cardio-metabolic risk z-score was applied and this consisted in calculating the sum of sex-specific z-scores for BMI, blood pressure, HOMA-IR, triglycerides and triglycerides:high-density lipoprotein cholesterol ratio.

Results

Fasting insulin and HOMA-IR were higher in SGA and LGA than AGA subjects both during childhood (all P<0.01) and adolescence (all P<0.01). Similarly, the clustered cardio-metabolic risk score was higher in SGA and LGA than AGA children (both P<0.05), and these differences among groups increased during adolescence (both P<0.05). Of note, a progression of the clustered cardio-metabolic risk score was observed from childhood to adolescence within SGA and within LGA subjects (both P<0.05).

Conclusions

SGA and LGA subjects showed an adverse cardio-metabolic profile during childhood when compared to AGA peers, with a worsening of this profile during adolescence. These findings indicate an overtime progression of insulin resistance and overall estimated cardiovascular risk from childhood to adolescence in SGA and LGA populations.

Aorta structural alterations in term neonates: the role of birth and maternal characteristics

AIM

To evaluate the influence of selected maternal and neonatal characteristics on aorta walls in term, appropriately grown-for-gestational age newborns.

METHODS

Age, parity, previous abortions, weight, height, body mass index before and after delivery, smoking, and history of hypertension, of diabetes, of cardiovascular diseases, and of dyslipidemia were all assessed in seventy mothers. They delivered 34 males and 36 females healthy term newborns who underwent ultrasound evaluation of the anteroposterior infrarenal abdominal aorta diameter (APAO), biochemical profile (glucose, insulin, total cholesterol, HDL and LDL cholesterol, triglycerides, fibrinogen, and D-dimers homeostasis model assessment [HOMAIR]index), and biometric parameters.

RESULTS

APAO was related to newborn length (r = +0.36; P = 0.001), head circumference (r = +0.37; P = 0.001), gestational age (r = +0.40, P = 0.0005), HOMA index (r = +0.24; P = 0.04), and D-dimers (r = +0.33, P = 0.004). Smoke influenced APAO values (odds ratio: 1.80; confidence interval 95%: 1.05-3.30), as well as diabetes during pregnancy (r = +0.42, P = 0.0002). Maternal height influenced neonatal APAO (r = +0.47, P = 0.00003). Multiple regression analysis outlined neonatal D-dimers as still significantly related to neonatal APAO values.

CONCLUSIONS

Many maternal and neonatal characteristics could influence aorta structures. Neonatal D-dimers are independently related to APAO.

Aorta structural alterations in term neonates: the role of birth and maternal characteristics

Aim. To evaluate the influence of selected maternal and neonatal characteristics on aorta walls in term, appropriately grown-for-gestational age newborns. Methods. Age, parity, previous abortions, weight, height, body mass index before and after delivery, smoking, and history of hypertension, of diabetes, of cardiovascular diseases, and of dyslipidemia were all assessed in seventy mothers. They delivered 34 males and 36 females healthy term newborns who underwent ultrasound evaluation of the anteroposterior infrarenal abdominal aorta diameter (APAO), biochemical profile (glucose, insulin, total cholesterol, HDL and LDL cholesterol, triglycerides, fibrinogen, and D-dimers homeostasis model assessment [HOMA_IR]index), and biometric parameters. Results. APAO was related to newborn length (r = +0.36; P = 0.001), head circumference (r = +0.37; P = 0.001), gestational age (r = +0.40, P = 0.0005), HOMA index (r = +0.24; P = 0.04), and D-dimers (r = +0.33, P = 0.004). Smoke influenced APAO values (odds ratio: 1.80; confidence interval 95%: 1.05–3.30), as well as diabetes during pregnancy (r = +0.42, P = 0.0002). Maternal height influenced neonatal APAO (r = +0.47, P = 0.00003). Multiple regression analysis outlined neonatal D-dimers as still significantly related to neonatal APAO values. Conclusions. Many maternal and neonatal characteristics could influence aorta structures. Neonatal D-dimers are independently related to APAO.

Medical record validation of maternal recall of pregnancy and birth events from a twin cohort

This study aims to assess the validity of maternal recall for several perinatal variables 8-10 years after pregnancy in a twin sample. Retrospective information was collected 8-10 years after the delivery event in a cohort of mothers from the University of Southern California Twin Study (N = 611) and compared with medical records for validity analysis. Recall of most variables showed substantial to perfect agreement (κ = 0.60-1.00), with notable exceptions for specific medical problems during pregnancy (κ ≤ 0.40) and substance use when mothers provided continuous data (e.g., number of cigarettes per day; r ≤ 0.24). With the exception of delivery method, neonatal intensive care unit admission, birth weight, neonatal information, and post-delivery complications were also recalled with low accuracy. For mothers of twins, maternal recall is generally a valid measure for perinatal variables 10 years after pregnancy. However, caution should be taken regarding variables such as substance use, medical problems, birth length, and post-delivery complications.

Ethnic variability in adiposity, thrifty phenotypes and cardiometabolic risk: addressing the full range of ethnicity, including those of mixed ethnicity

Ethnic groups vary in cardiometabolic risk, but the underlying mechanisms remain unclear. Several components of body composition variability (fat/lean ratio, fat distribution, lean mass composition and metabolism, and adipose tissue biology) are increasingly linked with cardiometabolic risk and vary substantially across ethnic groups. Constituents of lean mass are proposed to contribute to 'metabolic capacity', a generic trait favouring the maintenance of homeostasis. Adiposity is proposed to contribute to 'metabolic load', which at higher levels challenges metabolic homeostasis, elevating cardiometabolic risk. Ethnic differences in body composition, representing different load-capacity ratios, may therefore contribute to ethnic variability in cardiometabolic risk. Ecological and evolutionary factors potentially contributing to ethnic variability in body composition are explored. In contemporary populations, clinicians encounter an increasing range of ethnicity, along with many individuals of mixed-ethnic ancestry. Increasing understanding of the contribution of body composition to cardiometabolic risk may reduce the need to treat ethnic groups as qualitatively different. A conceptual model is proposed, treating insulin sensitivity and stroke risk as composite functions of body composition variables. Operationalizing this model may potentially improve the ability to assess cardiovascular risk across the full ethnicity spectrum, and to predict cardiometabolic consequences of excess weight gain.

Is the metabolic syndrome a "small baby" syndrome?: the bogalusa heart study

BACKGROUND

Metabolic syndrome has been called a "small baby syndrome," but other analyses suggest that postnatal growth is more important than birthweight, or that large babies are also at risk. The aim of this analysis was to examine whether there was a relationship between both low and high birthweight and metabolic syndrome, using multiple definitions of metabolic syndrome, and to determine whether this relationship varied by body size across the life course.

METHODS

Data from the Bogalusa Heart Study, a study of cardiovascular disease in children and young adults, were linked to birth certificate data. Metabolic syndrome was defined by the National Cholesterol Education Program, the International Diabetes Foundation, and the World Health Organization (WHO) definition. Small-for-gestational-age (SGA) was defined as birthweight <10(th) percentile by sex for gestational age and large-for-gestational-age (LGA) as birthweight >90(th) percentile. Birthweight-for-gestational-age was also examined as a continuous predictor. Chi-squared tests and logistic regression were used to examine the relationship between birth size and metabolic syndrome.

RESULTS

Higher birthweight-for-gestational-age was associated with a reduced risk of metabolic syndrome, especially by the WHO definition. After adjustment for body mass index (BMI), categorized birthweight was associated with metabolic syndrome, with the protective associations with LGA being stronger than the positive associations with SGA. Among the individual components of metabolic syndrome, higher waist circumference was associated with both SGA and LGA after BMI was controlled for. Effects of SGA and BMI at any age were largely independent rather than interactive.

CONCLUSIONS

SGA is associated with some, but not all, components of metabolic syndrome. The relationship between SGA and metabolic syndrome is partially confounded by later BMI.

Metabolic Syndrome in Adolescence

Background—

There are well-established predisposing factors for the development of metabolic syndrome (MetS) in childhood or adolescence, but no specific risk profile has been identified as yet. The Prediction of Metabolic Syndrome in Adolescence (PREMA) study was conducted (1) to construct a classification score that could detect children at high risk for MetS in adolescence and (2) to test its predictive accuracy.

Methods and Results—

In the derivation cohort (1270 children), data from natal and parental profile and from initial laboratory assessment at 6 to 8 years of age were used to detect independent predictors of MetS at 13 to 15 years of age according to the International Diabetes Federation definition. In the validation cohort (1091 adolescents), the discriminatory capacity of the derived prediction score was tested on an independent adolescent population. MetS was diagnosed in 105 adolescents in the derivation phase (8%), whereas birth weight <10th percentile (odds ratio, 6.02; 95% confidence interval, 2.53–10.12, P <0.001), birth head circumference <10th percentile (odds ratio, 4.15; 95% confidence interval, 2.04–7.14, P <0.001), and parental overweight or obesity (in at least 1 parent; odds ratio, 3.22; 95% confidence interval, 1.30–5.29, P <0.01) were independently associated with diagnosis of MetS in adolescence. Among adolescents in the validation cohort (86 [8%] with MetS), the presence of all these 3 predictors predicted MetS with a sensitivity of 91% and a specificity of 98%.

Conclusions—

The coexistence of low birth weight, small head circumference, and parental history of overweight or obesity may be useful for detection of children at risk of developing MetS in adolescence.

Early-life determinants of total and HDL cholesterol concentrations in 8-year-old children; the PIAMA birth cohort study

BACKGROUND

Adult cholesterol concentrations might be influenced by early-life factors, such as breastfeeding and birth weight, referred to as "early programming". How such early factors exert their influence over the life course is still poorly understood. Evidence from studies in children and adolescents is scarce and conflicting. We investigated the influence of 6 different perinatal risk factors on childhood total and HDL cholesterol concentrations and total-to-HDL cholesterol ratio measured at 8 years of age, and additionally we studied the role of the child's current Body Mass Index (BMI).

METHODS

Anthropometric measures and blood plasma samples were collected during a medical examination in 751 8-year-old children participating in the prospective Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort study. Linear and logistic regression were performed to estimate associations of total and HDL cholesterol concentrations with breastfeeding, birth weight, infant weight gain, maternal overweight before pregnancy, gestational diabetes and maternal smoking during pregnancy, taking into account the child's current BMI.

RESULTS

Linear regressions showed an association between total-to-HDL cholesterol ratio and maternal pre-pregnancy overweight (β = 0.15, Confidence Interval 95% (CI): 0.02, 0.28), rapid infant weight gain (β = 0.13, 95%CI: 0.01, 0.26), and maternal smoking during pregnancy (β = 0.14, 95%CI: 0.00, 0.29). These associations were partly mediated by the child's BMI.

CONCLUSION

Total-to-HDL cholesterol ratio in 8-year-old children was positively associated with maternal pre-pregnancy overweight, maternal smoking during pregnancy and rapid infant weight gain.

The influence of down-regulation of suppressor of cellular signaling proteins by RNAi on glucose transport of intrauterine growth retardation rats

Intrauterine growth retardation (IUGR) has been linked to metabolic syndrome including insulin resistance, and overexpression of suppressors of cytokine signaling (SOCSs) proteins is thought to be associated with increased whole-body insulin sensitivity. The insulin-resistant IUGR rat model was established by maternal food restriction (about 30% of the normal rats). The weight, length, and homeostasis model assessment of insulin resistance (HOMA-IR) of IUGR-born rats was higher than the control group. Insulin receptor substrate (IRS)-1 expression decreased, whereas SOCS-1 and SOCS-3 increased in the skeletal muscle of IUGR rats compared with the control group. The recombination plasmids PGPU6/GFP/Neo-SOCS-1small hairpin RNA (shRNA) and PGPU6/GFP/Neo-SOCS-3shRNA were transfected into skeletal muscle cells, and the shRNAs efficiently inhibited the expression of SOCS-1 and SOCS-3. Insulin-stimulated glucose transporter-4 (GLUT4) translocation was also dramatically increased. In conclusion, these data provide additional information on the mechanism of insulin resistance associated with IUGR. Down-regulation of SOCS-1 and SOCS-3 ameliorates the capacity of glucose transport and provides a potential gene therapy approach to managing metabolic syndrome.

Does birth weight influence physical activity in youth? A combined analysis of four studies using objectively measured physical activity

Animal models suggest growth restriction in utero leads to lower levels of motor activity. Furthermore, individuals with very low birth weight report lower levels of physical activity as adults. The aim of this study was to examine whether birth weight acts as a biological determinant of physical activity and sedentary time. This study uses combined analysis of three European cohorts and one from South America (n = 4,170). Birth weight was measured or parentally reported. Height and weight were measured and used to calculate Body Mass Index (BMI). PA was objectively measured using accelerometry for ≥3 days, ≥10 hours day. Data was standardized to allow comparisons between different monitors. Total physical activity was assessed as counts per minute (cpm), with time spent above moderate activity (MVPA) >2,000 counts and time spent sedentary (<100 counts). There was no evidence for an association between birth weight and total physical activity (p = 0.9) or MVPA (p = 0.7). Overall there was no evidence for an association between birth weight and sedentary time (p = 0.8). However in the Pelotas study we did find an association between higher birth weight (kg) and lower overall physical activity (cpm) (β = -31, 95%CI: -58, -46, p = 0.03) and higher birth weight and greater sedentary time (mins/day) (β = 16.4, 95%CI: 5.3, 27.5, p = 0.004), although this was attenuated and no longer significant with further adjustment for gestational age. Overall this combined analysis suggests that birth weight may not be an important biological determinant of habitual physical activity or sedentary behaviour in children and adolescents.

Association of maternally inherited GNAS alleles with African-American male birth weight

OBJECTIVE

Human birth weight variation has a significant genetic component and important clinical consequences. We performed a survey of single nucleotide polymorphisms (SNPs) in 14 candidate genes to identify associations with birth weight variation.

METHODS

SNP variation was surveyed in 221 healthy African-American mother-newborn pairs. Genes were selected based on previous association with obesity-related traits, significant differences in circulating protein levels in low birth weight pregnancies or association with newborn size in model organisms or growth disorders in humans. Association was tested via multiple linear regression with adjustment for significant covariables.

RESULTS

Under a dominant model SNP rs7754561 of ENPPI was significantly associated with birth weight. Among imprinted loci, maternal genotypes for SNP rs6026576 of GNAS were significantly associated with birth weight (additive and dominant models). This association was restricted to male offspring. Analyses that distinguished between alleles of paternal and maternal origin demonstrated that only maternally-transmitted alleles were associated with birth weight and that this association was restricted to male newborns.

CONCLUSION

The effect of only maternally-transmitted alleles of GNAS may be a consequence of the complex splicing and imprinting pattern of the GNAS gene, although the reason this effect is observed only among male newborns is unclear.

Relationship of low birth weight to pulsatile arterial function in asymptomatic younger adults: the Bogalusa Heart Study

BACKGROUND

Low birth weight, an indicator of intrauterine growth restriction, is associated with adult cardiovascular (CV) disease, type 2 diabetes, and adverse levels of CV risk factors. Impaired pulsatile arterial function is also an independent predictor of early vascular damage and related CV outcome. However, information is scant regarding the influence of low birth weight on pulsatile arterial function.

METHODS

The study cohort consisted of 538 black and white subjects (29% black, 42% male) aged 18-44 years (mean 36.7 years) enrolled in the Bogalusa Heart Study. Subjects were categorized into low birth weight and normal birth weight. Pulsatile arterial function was assessed in terms of large artery compliance, small artery compliance, and systemic vascular resistance by noninvasive radial artery pressure pulse contour analysis.

RESULTS

Blacks and females had significantly lower birth weight compared to their counterparts. Low vs. normal birth weight group had lower large artery compliance (13.3 ml/mm Hg x 10 vs. 15.5 ml/mm Hg x 10, P = 0.0002). Further, after adjusting for age, race, and sex, the large artery compliance increased across quartiles of increasing birth weight specific for race, sex, and gestational age (P for trend = 0.03). In multivariate regression model, adding race, sex, age, body surface area, systolic blood pressure, diastolic blood pressure, triglycerides/high-density lipoprotein cholesterol ratio one by one, the effect was attenuated but significant (beta = -0.067, P = 0.033).

CONCLUSIONS

The observed deleterious association of low birth weight on arterial wall dynamics in asymptomatic younger adults may account in part for the adverse CV risk in the Bogalusa sample.

The Relationship of Low Birth Weight to Blood Pressure, Cortisol Levels, and Reactivity in African American Adolescents: A Pilot Study

Epidemiological studies show a relationship between low birth weight (LBW) and adult cardiovascular disease. Blood pressure and cortisol hyper-responsiveness during physiologic stress may function as biological markers for hypertension. The purpose of this study was to explore the relationship of blood pressure and cortisol levels with induced physiologic stress to LBW. Forty-eight adolescents, 14 to 16 years old, were tested for blood pressure and cortisol levels at rest and in response to a physiological stressor. A history of LBW was obtained. Multivariate repeated measures analysis and chi-square analyses were used to determine the changes in blood pressure and cortisol.Forty-eight African American adolescents, mean age 14.98 years (SD = 0.33), completed the study. Thirteen adolescents (27%) reported LBW. Although not statistically significant, systolic and diastolic pressures were 6 mmHg and 2 mmHg, respectively, higher in the LBW group when compared with the normal birth weight (NBW) group (p = 0.33 and p = 0.21, and 6 (46%) had elevated blood pressures (p = 0.005)). Blood pressure changes, cardiovascular reactivity, elevated blood, or all of these were significantly higher in LBW African American adolescents (p = 0.006). Cardiovascular reactivity was not significant (p = 0.208)). The mean average cortisol levels were (18.8 nmol/dL (SD = 11.0) but comparable (p = 0.72)). The number of LBW adolescents with cortisol reactivity was significantly higher that in the NBW group (p = 0.041). This study adds support to the association of LBW to biological markers of hypertension in childhood.

Apgar scores reported in personal child health records: validity for epidemiological studies?

AIM

In epidemiological studies on children, information in the neonatal period that might affect children's long-term health could be extracted from the personal child health record (PCHR), because the booklet exists in most countries. We aimed to assess, in individual children, the validity of Apgar scores reported in the PCHR using maternity medical records as the gold standard.

METHODS

In two French hospitals, 435 women who had a child in January 2006 were recruited and 90% filled in a postal questionnaire 6 weeks after delivery, copying neonatal information (including Apgar scores) from the PCHR. This information was compared with data independently recorded at birth by physicians in maternity medical records.

RESULTS

We found that the proportion of missing Apgar scores in the PCHR was higher when scores in the medical records were lower. Moreover, Apgar scores reported in the PCHR were overestimated when scores in the medical records were low. Using medical records as the gold standard, specificity for PCHR-reported 1-min Apgar score was 100% and sensitivity 33%. Similar trends were found for the 5-min score. This supports the hypothesis that information considered as 'socially sensitive' by physicians may be intentionally altered in PCHRs.

CONCLUSIONS

Apgar scores reported in PCHRs may not yield reliable information for epidemiological studies. When the PCHR is the only source of information for the neonatal period in an epidemiological study, it would be preferable to use a composite neonatal indicator rather than the Apgar score.

[Birth weight and metabolic syndrome in adults: meta-analysis]

OBJECTIVES

To assess published evidences of the effect of birth weight on metabolic syndrome in adults.

METHODS

PubMed and LILACS databases were searched for articles published from 1966 through May 2006. The terms used were: "birth weight", "birthweight", "intra-uterine growth restriction (IUGR)", "fetal growth retardation", "metabolic syndrome", "syndrome X", "Reaven's X syndrome". Two hundred and twenty-four studies reporting estimates of the association between birth weight and metabolic syndrome or its components were considered eligible. Eleven studies provided odds ratios and were included in the meta-analysis.

RESULTS

All but two studies reported an inverse relationship between birth weight and metabolic syndrome. A comparison between low birth weight vs. normal birth weight subjects showed the random effects odds ratio for metabolic syndrome was 2.53 (95% CI: 1.57;4.08). The funnel plot graphic suggests a publication bias but, even in the studies with more than 400 subjects, the results remained significant (pooled odds ratio: 2.37 (95% CI: 1.15;4.90).

CONCLUSIONS

Low birth weight increases the risk of metabolic syndrome in adults.

Sex differences in the fetal programming of hypertension

BACKGROUND

Numerous clinical and experimental studies support the hypothesis that the intrauterine environment is an important determinant of cardiovascular disease and hypertension.

OBJECTIVE

This review examined the mechanisms linking an adverse fetal environment and increased risk for chronic disease in adulthood with an emphasis on gender differences and the role of sex hormones in mediating sexual dimorphism in response to a suboptimal fetal environment.

METHODS

This review focuses on current findings from the PubMed database regarding animal models of fetal programming of hypertension, sex differences in phenotypic outcomes, and potential mechanisms in offspring of mothers exposed to an adverse insult during gestation. For the years 1988 to 2007, the database was searched using the following terms: fetal programming, intrauterine growth restriction, low birth weight, sex differences, estradiol, testosterone, high blood pressure, and hypertension.

RESULTS

The mechanisms involved in the fetal programming of adult disease are multifactorial and include alterations in the regulatory systems affecting the long-tterm control of arterial pressure. Sex differences have been observed in animal models of fetal programming, and recent studies suggest that sex hormones may modulate activity of regulatory systems, leading to a lower incidence of hypertension and vascular dysfunction in females compared with males.

CONCLUSIONS

Animal models of fetal programming provide critical support for the inverse relationship between birth weight and blood pressure. Experimental models demonstrate that sex differences are observed in the pathophysiologic response to an adverse fetal environment. A role for sex hormone involvement is strongly suggested,with modulation of the renin-angiotensin system as a possible mechanism.

Evidence of Arteriolar Narrowing in Low-Birth-Weight Children

Background— Cardiovascular disease may have its origins in utero, but the influence of in utero growth on microvascular structure in children is unknown. We hypothesized that poor in utero growth is associated with narrower arteriolar caliber, which may help explain the established association of low birth weight with hypertension and cardiovascular disease in adulthood.

Methods and Results— We examined the relation of birth weight and other markers of in utero growth to microvascular caliber in the retina in a population-based study of 1369 6-year-old children in Sydney, Australia (Sydney Childhood Eye Study). Birth weight, birth length, and head circumference were obtained from parental records. Retinal arteriolar and venular calibers were measured from digitized retinal photographs by a validated computer-assisted method. Lower birth weight, shorter birth length, and smaller head circumference were associated with narrower retinal arteriolar caliber. Each kilogram decrease in birth weight was associated with a 2.3-μm (95% CI 0.6 to 3.9, P =0.01) narrower retinal arteriolar caliber after controlling for age, gender, ethnicity, height, body mass index, axial length, mean arterial blood pressure, and prematurity. Similar associations were observed between shorter birth length and smaller head circumference with narrower retinal arteriolar caliber.

Conclusions— Children who had lower birth weight, shorter birth length, and smaller head circumference had narrower retinal arteriolar calibers. These data support the concept that poor in utero growth may have an adverse influence on microvascular structure.

Perinatal factors reported by mothers: do they agree with medical records?

As perinatal events have been linked with diseases of later onset, epidemiological studies on child development and adult health require information on the perinatal period. When national neonatal registers do not exist, review of medical records may be impractical. However, neonatal information could be obtained by asking mothers to complete a postal questionnaire using data from the Personal Child Health Record (PCHR). We assessed agreement between medical records and mothers' reports for information on delivery and the newborn's condition at birth, based on the PCHR, a short time after delivery. Of 711 women giving birth in 3 French hospitals and invited to participate in the study, 580 (82%) completed a postal questionnaire 6 weeks after delivery, copying the data recorded in the PCHR when available. Information on pregnancy, delivery and the newborn's health at birth was independently extracted from medical records by physicians of the maternity departments. Agreement between medical records and maternal reports for a range of perinatal factors was assessed in 580 newborn-mother dyads using kappa coefficients. Agreement was excellent for first and second stages of delivery, gestational age, birth weight, birth size and head circumference (kappa coefficients 0.80-1.00) and good for hospitalization during pregnancy, but poor for Apgar scores. With this exception, mothers' reports appeared reliable when compared with medical records. As PCHRs exist in most developed countries, this approach could be used in epidemiological studies on child development to increase the reliability of mothers' reports of their newborn's condition at birth.

The association of low birth weight and physiological risk factors of hypertension in African American adolescents

Low birth weight (LBW) has been associated with increased blood pressure and the development of cardiovascular disease including hypertension. Elevated blood pressure, cortisol, and hyperresponsiveness during physiologic stress may function as hypertension biological markers. We examined the association of blood pressure and cortisol levels during induced physiologic stress with LBW in an African American adolescent population (n = 106).

METHODS AND RESULTS

Birth weight was obtained from parents. Blood pressure and cortisol levels were measured at rest and in response to an induced physiological stressor. Compared with normal birth weight group (n = 73), the LBW group (n = 33) demonstrated elevated (+4 mm Hg) diastolic pressure (P = .002) and cortisol hyperresponsiveness (P = .05). Seventy-nine percent of LBW adolescents had elevated blood pressure and/or cardiovascular reactivity (P = .04), and 39% had elevated blood pressures.

CONCLUSIONS

Low birth weight African American adolescents demonstrated physiological risk factors for hypertension, and these findings add support to the association between LBW and the development of hypertension.

Microcirculation in obesity: an unexplored domain

Obesity is traditionally linked to diabetes and cardiovascular diseases. Very recent experimental, clinical and epidemiological, sometimes provocative, data challenge this automaticity by showing that not the amount but the distribution of fat is the important determinant. Moderate abdominal fat accumulation may thus be more harmful than even consequent overweight. In view of the worldwide burden of obesity, factors leading to it in children and young adults must urgently be identified. Since obesity is a very complex cardiometabolic situation, this will require to focus investigations on uncomplicated obese subjects and adequate animal models. The recent discovery of intergenerational transmissions of obesity risk factors and also the key role played by gestational and perinatal events (epigenetic factors) give rise to completely new concepts and research avenues. Considering the potential close relationship between microcirculation and tissue metabolism, demonstrations of structural and/or functional abnormalities in microvascular physiology very early in life of subjects at risk for obesity might provide a solid basis for further investigations of such links. Microcirculation(arterioles, capillaries and venules) is conceivably a key compartment determining over one or several decades the translation of genetic and epigenetic factors into fat accumulation. Available animal models should serve to answer this cardinal question.

Association between paternally inherited haplotypes upstream of the insulin gene and umbilical cord IGF-II levels

The insulin (INS) and IGF 2 (IGF2) genes are in close proximity to each other and undergo maternal imprinting during fetal growth. We investigated the association between maternal and umbilical cord IGF 2 protein (IGF-II) levels and single nucleotide polymorphisms (SNPs) in the INS and IGF2 genes in 207 healthy African-American mother-newborn pairs. No association was found between maternal IGF-II levels and polymorphism in the INS-IGF2 locus. A significant association was found between newborn IGF-II levels and two SNPs (rs3842738 and rs689) at the 5' end of the INS-IGF2 locus. Analyses of haplotypes inferred from these two SNPs demonstrate a significant relationship between paternally transmitted haplotypes and newborn IGF-II levels, but no association with maternally transmitted haplotypes.

Association between small for gestational age and paternally inherited 5' insulin haplotypes

OBJECTIVE

To test the association between small for gestational age and polymorphisms in the insulin gene in newborns and their mothers, as well as the effect of the parental transmission of haplotypes.

SUBJECTS

Pairs of healthy African-American full-term newborns (N=207) and mothers were recruited from Memphis TN and Jackson MS with birth weights ranging from 2210 to 4735 g.

METHODS

Six single nucleotide polymorphisms (SNPs) located in the insulin (INS) and insulin-like growth factor 2 (IGF2) genes were genotyped in mothers and newborns. Haplotypes composed of three SNPs in the 5' region of the INS-IGF2 locus were computationally inferred. Odds ratios for risk of small for gestational age (SGA) birth were calculated for individual SNPs and inferred haplotypes in the newborns and in the mothers using logistic regression. For 162 mother--newborn pairs the parental transmission of the haplotypes could be inferred, and the risks for SGA birth were calculated for the three common haplotypes in this sample.

RESULTS

Three INS SNPs exhibited significant association with risk for SGA birth. The SNP alleles associated with increased risk for SGA were opposite in the maternal and newborn genomes, implying opposing influences on the rate of fetal growth. Consistent with these results, haplotypes composed of complementary nucleotide sequences (CAC at rs3842738, rs689 and rs3842748, respectively, in the newborn versus GTG in the mother) were significantly associated with risk for SGA birth. In analyses of haplotypes according to parental transmission, the same trend in risk for SGA was observed for both maternally and paternally transmitted haplotypes, although a significant difference in risk was observed only for paternally transmitted haplotypes.

CONCLUSION

Polymorphisms near the 5' end of the INS-IGF2 locus are significantly associated with risk for SGA birth with a major effect due to the paternally transmitted haplotype, which is preferentially expressed due to imprinting.