Birthweight, adult risk factors and incident coronary heart disease: the Caerphilly Study

Job strain and adverse pregnancy outcomes: A scoping review and meta-analysis

BACKGROUND

Previous studies have shown that job strain is associated with low birthweight (LBW), preterm birth (PTB), and small for gestational age (SGA). We conducted a scoping review and meta-analysis to assess the association between job strain and adverse pregnancy outcomes.

METHODS

A literature search was performed on PubMed. We included English-language studies that examined the association between job strain (based on the Karasek demand-control model) and pregnancy outcomes. We excluded letters, posters, reviews, and qualitative studies. Random effects meta-analysis was performed. Heterogeneity was assessed using τ2 and I2 statistics. Potential bias was assessed using standard funnel plots. Asymmetry was evaluated by Egger's test. Leave-one-out analysis was performed for sensitivity analyses.

RESULTS

Three eligible studies were found for LBW, seven for PTB, and four for SGA. The number of subjects ranged from 135 to 4889, and the prevalence of high job strain ranged from 6.64% to 33.9%. The pooled odds ratio and 95% confidence interval (CI) for LBW, PTB, and SGA were 1.23 (95% CI: 0.97, 1.56), 1.10 (95% CI: 1.00, 1.22), and 1.16 (95% CI: 0.97, 1.39) respectively, indicating modest associations. Heterogeneity for LBW and PTB may not be important but may be moderate for SGA. No publication bias was detected for LBW and PTB, but possible publication bias exists for SGA.

CONCLUSION

We found a modest association between job strain and PTB. Since job strain is only one of the many aspects of an unhealthy work environment, interventions that improve working conditions more broadly are needed.

The thrifty phenotype hypothesis: The association between ultrasound and Doppler studies in fetal growth restriction and the development of adult disease

Barker pioneered the idea that the epidemic of coronary heart disease in Western countries in the 20th century, which paradoxically coincided with improved standards of living and nutrition, has its origin in fetal life. Indeed, there is substantial evidence associating low birthweight because of fetal growth restriction with an increased risk of vascular disease in later adult life. These conclusions led to the second part of the Barker hypothesis, the thrifty phenotype, in which adaptation to undernutrition in fetal life leads to permanent metabolic and endocrine changes. Such changes are beneficial if the undernutrition persists after birth but may predispose the individual to obesity and impaired glucose tolerance if conditions improve. The hypothesis assumes that a poor nutrient supply during a critical period of in utero life may "program" a permanent structural or functional change in the fetus, thereby altering the distribution of cell types, gene expression, or both. The fetus, in response to placental undernutrition and to maintain sufficient vascular supply to the brain, decreases resistance to blood flow in the middle cerebral artery. Simultaneously, because of the limited blood supply to the fetus, the arterial redistribution process is accompanied by increased resistance to flow to other fetal vital organs, such as the heart, kidneys, liver, and pancreas. It may explain why individuals exposed to ischemic changes in utero develop dyslipidemia, lower nephron number, and impaired glucose tolerance, all factors contributing to metabolic syndrome later in life. Nevertheless, support for the hypotheses comes mainly from studies in rodents and retrospective epidemiologic studies. This review focused on ultrasound and Doppler studies of human fetal growth restriction in several fetal organs: the placenta, fetal circulation, brain, heart, kidneys, adrenal glands, liver, and pancreas. Support for the hypothesis was provided by animal studies involving conditions that create fetuses with growth restriction with effects on various fetal organs and by human studies that correlate impaired fetal circulation with the in utero development and function of fetal organs.

Prenatal exposure to multiple metals and birth outcomes: An observational study within the National Children's Study cohort

BACKGROUND

Prenatal exposure to metals may play an important role in fetal growth. However, the epidemiologic evidence for certain metals is sparse, and most of the existing research has focused on evaluating single metals in highly exposed target populations.

OBJECTIVES

We evaluated associations of cadmium, lead, manganese, selenium, and total mercury exposures during pregnancy with fetal growth using data from mother-infant pairs participating in the National Children's Study.

METHODS

Prenatal metal exposures were measured using maternal blood collected from 6 to 32 weeks of gestation. Birth outcomes, including gestational age, birthweight, birth length, head circumference, and ponderal index, were ascertained through physical measurement at birth or abstraction from medical records. Regression coefficients and their 95% confidence intervals were estimated from multivariable linear regression models in the overall study population as well as among male and female infants. We further evaluated pairwise metal-metal interactions.

RESULTS

Sex-specific associations were observed for lead, with inverse associations for birthweight, birth length, head circumference, and gestational age observed only among female infants. Sex-specific associations were also observed for selenium, with a positive association for birthweight observed among male infants; selenium was also positively associated with ponderal index and inversely associated with birth length among female infants. Overall, total mercury was inversely associated with birthweight and ponderal index, and the association with birthweight was stronger among female infants. No significant associations were observed with cadmium and manganese. In the metal-metal interaction analyses, we found evidence of a synergistic interaction between lead and total mercury and antagonistic interaction between selenium and total mercury with selected birth outcomes.

CONCLUSIONS

Our findings suggest that prenatal exposure to metals may be related to birth outcomes, and infant sex may modify these associations.

Exposure to antenatal corticosteroids and reduced respiratory sinus arrhythmia in adult survivors of extremely low birth weight

Purpose/aim: Antenatal corticosteroid (ACS) therapy has dramatically increased survival rates among extremely low birth weight (ELBW) infants. However, the long-term effects of ACS on autonomic nervous system function have not been explored. Using the world's oldest longitudinally followed cohort of ELBW infants we compared respiratory sinus arrhythmia (RSA) among ELBW survivors whose mothers received ACS (ELBW-S), those who did not (ELBW-NS) and normal birth weight (NBW) controls in their 20 and 30 s. Methods: Resting electrocardiogram (ECG) was recorded from ELBW-S (n = 28), ELBW-NS (n = 36), and matched NBW controls (n = 79) at 22-26 and 29-36 years. Resting RSA was compared across groups via analyses of covariance (ANCOVA), adjusting for sex, medication use, postnatal steroid exposure and the presence of chronic health conditions. RSA was also compared across assessments for each group. Results: At 29-36 years, resting RSA in ELBW-S was significantly lower than in NBW controls. RSA in the ELBW-NS group was intermediate between ELBW-S and NBW groups. Although the ELBW-S group also showed nominally reduced RSA compared to NBW controls at the 22-26-year visit, this difference was not statistically significant. Conclusions: ELBW survivors exposed to ACS had lower RSA than NBW controls during their 30 s, suggestive of a decline in parasympathetic input to heart. ELBW survivors who received ACS may be particularly vulnerable to cardiovascular problems in later life.

Long-term cardiovascular consequences of fetal growth restriction: biology, clinical implications, and opportunities for prevention of adult disease

In the modern world, cardiovascular disease is a leading cause of death for both men and women. Epidemiologic studies consistently have suggested an association between low birthweight and/or fetal growth restriction and increased rate of cardiovascular mortality in adulthood. Furthermore, experimental and clinical studies have demonstrated that sustained nutrient and oxygen restriction that are associated with fetal growth restriction activate adaptive cardiovascular changes that might explain this association. Fetal growth restriction results in metabolic programming that may increase the risk of metabolic syndrome and, consequently, of cardiovascular morbidity in the adult. In addition, fetal growth restriction is strongly associated with fetal cardiac and arterial remodeling and a subclinical state of cardiovascular dysfunction. The cardiovascular effects ocurring in fetal life, includes cardiac morphology changes, subclinical myocardial dysfunction, arterial remodeling, and impaired endothelial function, persist into childhood and adolescence. Importantly, these changes have been described in all clinical presentations of fetal growth restriction, from severe early- to milder late-onset forms. In this review we summarize the current evidence on the cardiovascular effects of fetal growth restriction, from subcellular to organ structure and function as well as from fetal to early postnatal life. Future research needs to elucidate whether and how early life cardiovascular remodeling persists into adulthood and determines the increased cardiovascular mortality rate described in epidemiologic studies.

Effects of prenatal low protein and postnatal high fat diets on visceral adipose tissue macrophage phenotypes and IL-6 expression in Sprague Dawley rat offspring

Adipose tissue macrophages (ATM) are implicated in adipose tissue inflammation and obesity-related insulin resistance. Maternal low protein models result in fetal programming of obesity. The study aims to answer whether maternal undernutrition by protein restriction affects the ATM M1 or M2 phenotype under postnatal high fat diet in F1 offspring. Using a rat model of prenatal low protein (LP, 8% protein) diet followed by a postnatal high fat energy diet (HE, 45% fat) or low fat normal energy diet (NE, 10% fat) for 12 weeks, we investigated the effects of these diets on adiposity, programming of the offspring ATM phenotype, and the associated inflammatory response in adipose tissue. Fat mass in newborn and 12-week old LP fed offspring was lower than that of normal protein (20%; NP) fed offspring; however, the adipose tissue growth rate was higher compared to the NP fed offspring. While LP did not affect the number of CD68⁺ or CD206⁺ cells in adipose tissue of NE offspring, it attenuated the number of these cells in offspring fed HE. In offspring fed HE, LP offspring had a lower percentage of CD11c⁺CD206⁺ ATMs, whose abundancy was correlated with the size of the adipocytes. Noteworthy, similar to HE treatment, LP increased gene expression of IL-6 within ATMs. Two-way ANOVA showed an interaction of prenatal LP and postnatal HE on IL-6 and IL-1β transcription. Overall, both LP and HE diets impact ATM phenotype by affecting the ratio of CD11c⁺CD206⁺ ATMs and the expression of IL-6.

Pediatric Blood Pressure and Adult Preclinical Markers of Cardiovascular Disease

A high blood pressure level in adults is considered the single most important modifiable risk factor for global disease burden, especially those of cardiovascular (CV) origin such as stroke and ischemic heart disease. Because blood pressure levels have been shown to persist from childhood to adulthood, elevations in pediatric levels have been hypothesized to lead to increased CV burden in adulthood and, as such, might provide a window in the life course where primordial and primary prevention could be focused. In the absence of substantive data directly linking childhood blood pressure levels to overt adult CV disease, this review outlines the available literature that examines the association between pediatric blood pressure and adult preclinical markers of CV disease.

Hypertension and diabetes in Africa: design and implementation of a large population-based study of burden and risk factors in rural and urban Malawi

Background

The emerging burden of cardiovascular disease and diabetes in sub-Saharan Africa threatens the gains made in health by the major international effort to combat infectious diseases. There are few data on distribution of risk factors and outcomes in the region to inform an effective public health response. A comprehensive research programme is being developed aimed at accurately documenting the burden and drivers of NCDs in urban and rural Malawi; to design and test intervention strategies. The programme includes population surveys of all people aged 18 years and above, linking individuals with newly diagnosed hypertension and diabetes to healthcare and supporting clinical services. The successes, challenges and lessons learnt from the programme to date are discussed.

Results

Over 20,000 adults have been recruited in rural Karonga and urban Lilongwe. The urban population is significantly younger and wealthier than the rural population. Employed urban individuals, particularly males, give particular recruitment challenges; male participation rates were 80.3 % in the rural population and 43.6 % in urban, whilst female rates were 93.6 and 75.6 %, respectively. The study is generating high quality data on hypertension, diabetes, lipid abnormalities and risk factors.

Conclusions

It is feasible to develop large scale studies that can reliably inform the public health approach to diabetes, cardiovascular disease and other NCDs in Sub-Saharan Africa. It is essential for studies to capture both rural and urban populations to address disparities in risk factors, including age structure. Innovative approaches are needed to address the specific challenge of recruiting employed urban males.

Perinatal risk factors for premature ischaemic heart disease in a Swedish national cohort

OBJECTIVE

Several studies have reported associations between restricted fetal development, as shown by birth weight or birth length, and later ischaemic heart disease (IHD). However, few studies have examined the importance of these perinatal factors when taking into account gestational age at birth, hereditary factors, sociodemographic factors and comorbidities. This study investigated the importance of perinatal risk factors for premature IHD and myocardial infarction (MI) in a large Swedish cohort.

SETTING AND PARTICIPANTS

National cohort study of 1,970,869 individuals who were live-born in Sweden in 1973 through 1992, and followed up to 2010 (ages 18-38 years).

PRIMARY AND SECONDARY OUTCOME MEASURES

The main outcome was IHD, and the secondary outcome was MI.

RESULTS

A total of 668 individuals were diagnosed with IHD in 18.8 million person-years of follow-up. After adjusting for gestational age at birth, sociodemographic factors, comorbidities and family history of IHD, low fetal growth was associated with increased risk of IHD (HR for <-2 vs -1 to <1 SD, 1.54; 95% CI 1.15 to 2.07; p=0.004) and increased risk of MI (HR for <-2 vs -1 to <1 SD, 2.48; 95% CI 1.66 to 3.71; p<0.001) in young adulthood. In contrast, gestational age at birth was not associated with the risk of IHD or MI.

CONCLUSIONS

In this large national cohort, low fetal growth was strongly associated with IHD and MI in young adulthood, independently of gestational age at birth, sociodemographic factors, comorbidities and family history of IHD.

Can 'early programming' be partly explained by smoking? Results from a prospective, population-based cohort study

BACKGROUND

Numerous studies have focused the association between low birthweight and later disease. Our objective was to study the association between birthweight and later adult smoking and thereby explore a possible mechanism for the association between low birthweight and later adult disease.

METHODS

We studied associations between birthweight of women (n=247704) born in 1967-1995 and smoking habits at the end of their pregnancy 13-42 years later in a prospective, population-based cohort study from The Medical Birth Registry of Norway. Similarly, the association between birthweight of men (n=194393) and smoking habits of their partners were assessed. Finally, we studied the relation between smoking habits of the participating women and the cause specific death of their mothers (n=222808).

RESULTS

Twenty per cent of women with birthweight less than 2000 g were adult daily smokers compared with 11% with birthweight 4000-4499 g [relative risk=1.8, 95% confidence interval 1.4, 2.2]. Similarly, we found an association between men's birthweight and their partners smoking habits. Mothers of smoking women had doubled risk of dying from lung cancer and from cardiovascular disease compared with mothers of non-smoking women.

CONCLUSIONS

Being born with low birthweight is associated with smoking in adulthood. Associations of adult smoking with partners' birthweight and mothers' smoking-related causes of death suggest a shared smoking environment, and may account for some of the established association between birthweight and later cardiovascular disease.

Birth weight, season of birth and postnatal growth do not predict levels of systemic inflammation in Gambian adults

Objectives

Studies testing whether systemic inflammation might lie on the causal pathway between aberrant fetal and post-natal growth patterns and later cardiovascular disease have been inconclusive, possibly due to the use of single markers of unknown predictive value. We used repeated measures of a comprehensive set of inflammatory markers to investigate the relationship between early life measures and systemic inflammation in an African population.

Methods

Individuals born in three rural villages in The Gambia, and for whom early life measurements were recorded, were traced (n = 320). Fasting levels of eight inflammatory markers (C-reactive protein, serum amyloid A, orosomucoid, fibrinogen, α 1-antichymotrypsin, sialic acid, interleukin-6 and neopterin) were measured, and potential confounding factors recorded. The association between early life measurements and systemic inflammation was assessed using regression analysis.

Results

Levels of most markers were unrelated to early growth patterns. In analyses adjusted for age and sex, more rapid growth between birth and 3 months of age was associated with higher levels of fibrinogen, orosomucoid, and sialic acid. These relationships persisted after further adjustment for body mass index but after full adjustment only the association with fibrinogen remained.

Conclusions

This study provides little evidence that size at birth or growth in early infancy determine levels of inflammatory markers in young Gambian adults. Am. J. Hum. Biol. 25:457–464, 2013. © 2013 Wiley Periodicals, Inc.

Weight status in adolescence is associated with later life functional limitations

OBJECTIVE

This study examines the relationship between weight status in adolescence and later life functional limitations.

METHOD

We use the Wisconsin Longitudinal Study to characterize the relationship between standardized relative body mass ascertained from high school photograph portraits in 1957 and self-reported functional imitations in 2004.

RESULTS

Compared to individuals with normal body mass, those who were overweight in high school had poorer later life physical function, with observed gender differences. Women who were underweight in adolescence had better functioning in older adulthood than their normal weight counterparts. This relationship, however, was not found among men.

CONCLUSIONS

These findings underscore the long-term consequences of being overweight in adolescence on the functional disadvantages conferred in late life.

Associations of maternal prepregnancy body mass index and gestational weight gain with adult offspring cardiometabolic risk factors: the Jerusalem Perinatal Family Follow-up Study

BACKGROUND

Accumulating evidence demonstrates that both maternal prepregnancy body mass index (mppBMI) and gestational weight gain (GWG) are associated with adult offspring adiposity. However, whether these maternal attributes are related to other cardiometabolic risk factors in adulthood has not been comprehensively studied.

METHODS AND RESULTS

We used a birth cohort of 1400 young adults born in Jerusalem who had extensive archival data and clinical information at 32 years of age to prospectively examine the associations of mppBMI and GWG with adiposity and related cardiometabolic outcomes. Greater mppBMI, independently of GWG and confounders, was significantly associated with higher offspring BMI, waist circumference, systolic and diastolic blood pressures, insulin, and triglycerides and with lower high-density lipoprotein cholesterol. For example, the effect sizes were translated to nearly 5 kg/m(2) higher mean BMI, 8.4 cm higher waist circumference, 0.13 mmol/L (11.4 mg/dL) higher triglycerides, and 0.10 mmol/L (3.8 mg/dL) lower high-density lipoprotein cholesterol among offspring of mothers within the upper mppBMI quartile (mppBMI >26.4 kg/m(2)) compared with the lower quartile (mppBMI <21.0 kg/m(2)). GWG, independently of mppBMI, was positively associated with offspring adiposity; differences of 1.6 kg/m(2) in BMI and 2.4 cm in waist were observed when offspring of mothers in the upper (GWG >14 kg) and lower (GWG <9 kg) quartiles of GWG were compared. Further adjustment for offspring adiposity attenuated the observed associations to the null.

CONCLUSIONS

Maternal size both before and during pregnancy is associated with cardiometabolic risk factors in young adult offspring. The associations appear to be driven mainly by offspring adiposity. Future studies that explore mechanisms underlying the intergenerational cycle of obesity are warranted to identify potentially novel targets for cardiometabolic risk-reduction interventions.

Birthweight and mortality in adulthood: a systematic review and meta-analysis

BACKGROUND

Small birth size may be associated with increased risk of cardiovascular diseases (CVD), whereas large birth size may predict increased risk of obesity and some cancers. The net effect of birth size on long-term mortality has only been assessed in individual studies, with conflicting results.

METHODS

The Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines for conducting and reporting meta-analysis of observational studies were followed. We retrieved 22 studies that assessed the association between birthweight and adult mortality from all causes, CVD or cancer. The studies were systematically reviewed and those reporting hazard ratios (HRs) and 95% confidence intervals (95% CIs) per kilogram (kg) increase in birthweight were included in generic inverse variance meta-analyses.

RESULTS

For all-cause mortality, 36,834 deaths were included and the results showed a 6% lower risk (adjusted HR = 0.94, 95% CI: 0.92-0.97) per kg higher birthweight for men and women combined. For cardiovascular mortality, the corresponding inverse association was stronger (HR = 0.88, 95% CI: 0.85-0.91). For cancer mortality, HR per kg higher birthweight was 1.13 (95% CI: 1.07-1.19) for men and 1.04 (95% CI: 0.98-1.10) for women (P(interaction) = 0.03). Residual confounding could not be eliminated, but is unlikely to account for the main findings.

CONCLUSION

These results show an inverse but moderate association of birthweight with adult mortality from all-causes and a stronger inverse association with cardiovascular mortality. For men, higher birthweight was strongly associated with increased risk of cancer deaths. The findings suggest that birthweight can be a useful indicator of processes that influence long-term health.

Childhood body mass index and adult pro-inflammatory and pro-thrombotic risk factors: data from the New Delhi birth cohort

OBJECTIVE

Weight gain and growth in early life may influence adult pro-inflammatory and pro-thrombotic cardiovascular risk factors.

METHODS

Follow-up of a birth cohort in New Delhi, India, whose weight and height were measured every 6 months until age 21 years. Body mass index (BMI) at birth, during infancy (2 years), childhood (11 years) and adulthood (26-32 years) and BMI gain between these ages were analysed in 886 men and 640 women with respect to adult fibrinogen, high-sensitivity C-reactive protein (hsCRP) and plasminogen activator inhibitor-1 (PAI-1) concentrations.

RESULTS

All the pro-inflammatory/pro-thrombotic risk factors were higher in participants with higher adiposity. In women, BMI at birth and age 2 years was inversely related to fibrinogen (P = 0.002 and 0.05) and, after adjusting for adult adiposity, to hsCRP (P = 0.02 and 0.009). After adjusting for adult adiposity, BMI at 2 years was inversely related to hsCRP and PAI-1 concentrations (P < 0.001 and 0.02) in men. BMI gain between 2 and 11 years and/or 11 years to adulthood was positively associated with fibrinogen and hsCRP in women and with hsCRP and PAI-1 in men.

CONCLUSIONS

Thinness at birth or during infancy, and accelerated BMI gain during childhood/adolescence are associated with a pro-inflammatory/pro-thrombotic state in adult life. An altered inflammatory state could be one link between small newborn/infant size and adult cardiovascular disease. Associations between pro-inflammatory markers and childhood/adolescent BMI gain are probably mediated through adult adiposity.

Low birth weight and lung function in adulthood: retrospective cohort study in China, 1948-1996

OBJECTIVE

The goal was to determine whether the components of low lung function in adulthood were associated with low birth weight in a Chinese population.

METHODS

A retrospective cohort study was conducted from December 1995 to August 1996. A total of 627 men and women who were born between 1948 and 1954 were recruited; lung function indices were tested and respiratory diseases were examined in the Peking Union Medical College Hospital. Information on variables was recorded, and multivariate analysis of variance was performed to evaluate associations.

RESULTS

Significant associations were observed between birth weight and forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), and peak expiratory flow (PEF) in adulthood, after adjustment for maternal age, gestational week, offspring's gender, birth height, history of dyspnea and asthma, lung diseases before 16 years of age, lung diseases after measles and pneumonia before 16 years of age, cough with sputum within 2 years, current asthma, taking medicine for asthma, adult BMI, male alcohol consumption, and male smoking (P < .001). Linear trends between birth weight and FEV(1), FVC, and PEF were noted (P < .001, 1-way analysis of variance); FEV(1), FVC, and PEF values increased with increasing birth weight. Low birth weight was associated with the FEV(1)/FVC predictive value (P < .05), but there was no linear trend (P > .05).

CONCLUSIONS

Low birth weight may increase the prevalence of and risk for low lung function in adulthood in the Chinese population. The development of lung function may be affected by hypogenesis in utero.

Insulin resistance: the possible link between gestational diabetes mellitus and hypertensive disorders of pregnancy

Gestational hypertension, preeclampsia, and diabetes are all associated with increased risks of poor maternal and perinatal outcomes. Pregnant women with gestational diabetes have been shown in population studies to have increased risk of pregnancy-associated hypertension compared with nondiabetic women. Moreover, pregnant patients with hypertension are at increased risk for developing gestational diabetes mellitus. It has been hypothesized that this association could be due, at least in part, to insulin resistance. Although insulin resistance is a physiologic phenomenon in normal pregnancy, in predisposed individuals this could lead to hyperinsulinemia with the development of gestational hypertension, gestational diabetes mellitus, or both.

Is body mass index before middle age related to coronary heart disease risk in later life? Evidence from observational studies

Objective

Although obesity beginning early in life is becoming more common, its implications for coronary heart disease (CHD) risk in later life remain uncertain. We examined the relationship of body mass index (BMI) before 30 years of age to CHD risk in later life.

Design

Systematic review of published studies relating BMI between age 2-30 years to later CHD risk. Studies were identified using Medline (1950 onwards), Embase (1980 onwards) and Web of Science (1970 onwards) databases (to November 2007).

Measurements

Relative risks (RR) of CHD associated with a 1 standard deviation (SD) increase in BMI (most based on a narrow age-range at measurement) were extracted by 2 authors independently, and combined using random-effect models.

Results

Fifteen studies provided seventeen estimates (731,337 participants, 23,894 CHD events) of the association of early BMI to later CHD outcome. BMI in early childhood (2 to 6 years, 3 estimates) showed a weak inverse association with CHD risk (RR 0.94, 95% CI 0.82-1.07). BMI in later childhood (7 to <18 years, 7 estimates) and BMI in early adult life (18-30 years, 7 estimates) were both positively related to later CHD risk (RR 1.09, 95% CI 1.00-1.20; RR 1.19, 95% CI 1.11-1.29 respectively). However, there was considerable statistical heterogeneity between study estimates. Results were unaffected by adjustment for social class and/or cigarette smoking, blood pressure and/or total cholesterol, in studies with available data. Gender and year of birth (1900-1976) had little effect on the association.

Conclusions

BMI is positively related to CHD risk from childhood onwards; the associations in young adults are consistent with those observed in middle age. Long-term control of BMI from childhood may be important to reduce the risk of CHD.

Breast-feeding influences on later life--cardiovascular disease

Current evidence, almost exclusively from observational studies, provides a rather mixed picture. From the few studies that have been able to look at fatal or non-fatal cardiovascular events, there is little indication that breast-feeding is associated with either an increased or decreased risk. With respect to blood pressure, the meta-analyses suggest a small but statistically significant lowering of around 1 mmHg SBP associated with having been breast-fed in infancy. However, there is a strong indication from the meta-analyses that even this small effect may partly be accounted for by publication bias. The strongest evidence for an effect of breast-feeding reviewed in this chapter is for serum lipids, where there is good evidence that being breast-fed is associated with an increase in serum total cholesterol in infancy. In childhood there appears to be no association, while in adults there is some indication of breast-feeding being associated with a small decline in total cholesterol levels. As already outlined at the start of the chapter, this whole area of research is made particularly difficult by the fact that breast-feeding can be defined in many different ways. Some studies use definitions that are equivalent to exclusive breast-feeding prior to weaning, while others define it as having ever been breast-fed. This problem of classification is likely to dilute any real associations that may exist. The other major problem is one of interpretation. A result implying that breast-feeding is a "good thing" for cardiovascular health could equally be construed as evidence for a "bad" effect of bottle-feeding. From these data alone, we cannot convincingly determine which conclusion is correct. This is not simply a philosophical debating point. As discussed above in relation to the interpretation of results from the randomised trial of infant feeding, the issue has implications for all research on this topic. Some progress in this area will be made if studies are conducted which define breast-feeding in a more precise and comparable way, and take account of the composition of alternative infant feeds. This will be most easily done by following up more recent study populations that were originally recruited to look at shorter-term effects of infant feeding on outcomes such as growth. With respect to randomised trial evidence, looking at the cardiovascular disease risk profiles of children (and later adults) who were part of the PROBIT trial in Belarus (see Chapters 5 and 10) is likely to prove fruitful.

Weight at birth and all-cause mortality in adulthood

BACKGROUND

Small size at birth is associated with subsequent cardiovascular disease and diabetes, and large size is associated with obesity and cancer. The overall impact of these opposing effects on mortality throughout the lifespan is unclear because causes of death change with age.

METHODS

We investigated the association of birth weight with adult all-cause mortality using a Danish school-based cohort of 216,464 men and women born from 1936 through 1979. The cohort was linked to vital statistic registers. The main outcome was all-cause mortality from ages 25 through 68 years. Associations with death from cancer, circulatory disease, and all other causes were also examined.

RESULTS

During 5,205,477 person-years of follow-up, 11,149 deaths occurred among men and 6609 among women. The cumulative hazard ratios of the association between birth weight categories and all-cause mortality was constant for all ages investigated and did not differ between men and women. Compared with subjects having birth weights in the reference category (3251-3750 g), those with the lowest birth weights (2000-2750 g) had 17% higher mortality (95% confidence interval = 1.11-1.22), and those with the highest birth weights (4251-5500 g) had 7% higher mortality (1.01-1.15) from all causes. The association of birth weight with cancer increased linearly, whereas the association of birth weight with circulatory disease and all other causes was U-shaped.

CONCLUSIONS

To the degree that the association of birth weight with adult survival is causal, the U-shaped association between birth weight and adult mortality suggests that population increases in birth weight may not necessarily lead to improved health in adulthood.

Perinatal Risk Factors for Ischemic Heart Disease

Background— Several studies have reported an association between low birth weight and ischemic heart disease, but it remains unclear whether the association is mediated through poor fetal growth or short gestational duration.

Methods and Results— In a cohort study, we have identified all subjects born preterm or with a low birth weight at 4 major delivery units in Sweden from 1925 through 1949. For comparison, an equal number of subjects with none of these criteria were identified within the same source population. The study population consists of 6425 subjects, of whom 2931 were born before 37 weeks of gestation and 2176 had a birth weight <2500 g. Fetal growth was estimated through birth weight for gestational age. The cohort was followed up for occurrence of ischemic heart disease through the nationwide Hospital Discharge and Cause of Death Registries during the period of 1987 through 2002. In the cohort, 617 cases of ischemic heart disease occurred. Compared with subjects with a normal fetal growth, those born small for gestational age (birth weight ≤−2 SD below the mean) were at increased risk of ischemic heart disease (adjusted hazard ratio, 1.64; 95% confidence interval, 1.23 to 2.18). The negative association between fetal growth and risk of ischemic heart disease was independent of gestational duration.

Conclusions— The association between low birth weight and adult risk of ischemic heart disease appears to be mediated entirely by poor fetal growth.

What evidence is there that adjustment for adult height influences the relationship between birth weight and blood pressure?

BACKGROUND

The inverse association between birth weight and blood pressure may partly be the result of inappropriate adjustment for adult body size, but it remains unclear whether adjustment for adult height elicits this effect.

AIM

The study investigated the impact of adjustment for adult height on the relationship between birth weight and blood pressure.

METHODS

A systematic search of Medline from 1996 to 2006 was conducted using the terms 'birth weight', 'blood pressure' and 'hypertension', and any papers containing linear regression analyses of blood pressure on birth weight for populations with an average age of 25+ were eligible for inclusion in comparative meta-analyses.

RESULTS

None of the 30 studies identified had published regression coefficients for blood pressure on birth weight before and after adjustment for adult height, and only two studies were found to adjust for adult height at all. Data from these studies were obtained, and it was found that adjustment for height made the association between birth weight and systolic blood pressure (SBP) more negative in one study but less negative in the other. When compared with meta-analyses of comparable models, it was found that both studies were substantially different from the combined estimate of the relationship between birth weight and SBP.

CONCLUSIONS

Both the differences between the two selected studies and their differences from the combined estimates obtained by meta-analysis are likely to be due to differences in the age of the participants. The relationship between birth weight and SBP tended to become more strongly inverse in studies with older participants. Additionally, the correlations between height and SBP were found to change from positive to negative with increasing age, which explained the differential impact of adjustment for height in the two selected studies. It therefore appears that adjustment for height may have little effect for older participants, but more so for younger participants.

Epidemiology, genes and the environment: lessons learned from the Helsinki Birth Cohort Study

Nonoptimal growth during fetal life and infancy is associated with an increased risk of coronary heart disease and type 2 diabetes later in life. This early pattern of growth is associated with an increased disease risk especially when followed by a relative gain in body size later in childhood. Genetic factors are closely involved in growth and disease pathogenesis and gene-early life environmental interactions will be described affecting adult health outcomes. This overview will primarily focus upon findings from the Helsinki Birth Cohort Study consisting of 15846 subjects born 1924-1944 on whom growth data and information on adult health are available.

Cardiovascular Diseases, Aging and the Gender Gap in the Human Longevity

This brief communication probes into the biological meaning of the gender gap in longevity and its possible ramifications to the expression of cardiovascular diseases in humans. It addresses the potential role of the estrogen and the X chromosome in the longer life span of women than men in modern societies. In addition, it links features of the reproductive and post-reproductive periods with cardiovascular diseases and longevity in women.

Is birth weight a risk factor for ischemic heart disease in later life?

BACKGROUND

An inverse association between birth weight and ischemic heart disease (IHD) has been seen in observational studies.

OBJECTIVE

We wanted to determine the strength and consistency of the association between birth weight and subsequent IHD.

DESIGN

We conducted a systematic review of observational studies.

RESULTS

Seventeen published studies of birth weight and subsequent IHD were identified that included a total of 144,794 singletons. Relative risk estimates for the association between birth weight and IHD were available from 16 of these studies. Additional data from 2 unpublished studies of 3801 persons were also included. In total, the analyses included data from 18 studies on 4210 nonfatal and 3308 fatal IHD events in 147,009 persons. The mean weighted estimate for the association between birth weight and the combined outcome of nonfatal and fatal IHD was 0.84 (95% CI: 0.81, 0.88) per kilogram of birth weight (P<0.0001). No significant heterogeneity was observed between estimates in different studies (P=0.09), nor was there evidence of publication bias (P=0.3, Begg test). Neither restricting the analysis to fatal IHD events nor adjusting for socioeconomic status had any appreciable effect on the findings.

CONCLUSIONS

These findings are consistent with a 1 kg higher birth weight being associated with a 10-20% lower risk of subsequent IHD. However, even if causal, interventions to increase birth weight are unlikely to reduce the incidence of IHD materially. Further studies are needed to determine whether the observed association reflects a stronger underlying association with a related exposure or is due (at least in part) to residual confounding.

A life-course approach to the aetiology of late-onset dementias

Substantial progress has been made in the understanding of the neurobiology of dementias, but comprehensive causal models are not available. Genetic and environmental factors probably interact to determine vulnerability to the dementias. The life-course approach to age-related diseases, when systematically applied to the dementias, provides opportunities to identify the nature and timing of environmental contributions. We discuss the relevance of the fetal origins of adult disease hypothesis to the dementias. Associations between the dementias (most often described as Alzheimer's disease) and ischaemic heart disease, obesity, hypertension, hyperlipidaemia, and non-insulin-dependent diabetes mellitus are set against associations between dementias and childhood intelligence, low educational attainments, low socioeconomic status, occupation, and lifetime dietary history. Biological mechanisms that explain how fetal development might influence the risk of adult disease may be relevant to many age-related diseases including the dementias and, possibly, to the biology of ageing.

Correlations of siblings' and mothers' utilisation of primary and hospital health care: a record linkage study in Western Australia

A relationship between maternal and child use of general practitioners (GPs) has been shown to exist for some time, however, the reasons for this relationship are not clear and the extent to which this relationship extends to tertiary care is unknown. The aim of this study was to examine the relationships between the utilisation of health care by siblings and mothers over a 14 year period. A retrospective cohort study of 756 mothers and their 1494 children up to age 14 years was conducted in three general practices in Western Australia. Medicare claims and hospital morbidity records for 1984-1997 were linked using deterministic and probabilistic matching. Generalised Estimating Equations and correlations were used to examine the relationships between the utilisation of primary and hospital health care by family members. Significant correlations were found between hospital admissions of all participants and their GP visits, specialist visits, pathology and diagnostic imaging combined and hospital length of stay. There was a strong association between siblings' use of GPs. A child's rate of GP attendance increased with that of its mother. There was a weak but significant relationship between siblings' use of hospitals, and a child's hospital admission rate increased with that of its mother. It is concluded that there is a strong relationship between siblings' use of GPs and a weaker but still significant association between the hospital admissions of siblings. As expected, there were strong associations between mother and child visits to GPs. There was also an association between a mother's use of hospital and that of her children. This finding reduces the plausibility that the relationships found between utilisation of health care by siblings and mothers can be explained entirely by behavioural factors, and suggests the presence of intergenerational correlation of morbidity.

Embryonic and fetal programming of physiological disorders in adulthood

In the past decade, data from numerous epidemiological studies have indicated strong inverse associations between birth weight and risk of coronary heart disease, hypertension, type 2-diabetes, and other diseases in adulthood. The "Barker hypothesis" thus postulates that a number of organ structures and functions undergo programming during embryonic and fetal life. This developmental programming determines the set points of physiological and metabolic responses in adult life. Alterations of nutrient availability during gestation may lead to developmental adaptations, via hormonal maneuvers by the embryo and fetus that readjust these set points. These adaptive measures have short-term benefits to the embryo and fetus, so that the newborn will be better prepared for the adverse environment (e.g., undernutrition). However, adequate nutritional support during postnatal life that enables catch-up growth may create metabolic conflicts that predispose the adult to aberrant physiological functions and, ultimately, increased risk of disease. It is plausible that other adverse in utero conditions, including exposure to developmental toxicants, may similarly alter adult disease susceptibility. This article provides an overview of the Barker hypothesis, its supporting evidence, the current advances in understanding the biological mechanisms underlying this phenomenon, and its implications for developmental toxicology.

Longitudinal study of birth weight and adult body mass index in predicting risk of coronary heart disease and stroke in women

OBJECTIVES

To determine whether birth weight and adult body size interact to predict coronary heart disease in women, as has been observed for men. To determine whether birth weight and adult body size interact to predict risk of stroke.

DESIGN

Longitudinal cohort study.

SETTING AND PARTICIPANTS

66,111 female nurses followed since 1976 who were born of singleton, term pregnancies and reported their birth weight in 1992.

MAIN OUTCOME MEASURES

1504 events of coronary heart disease (myocardial infarction or sudden cardiac death) and 1164 strokes.

RESULTS

For each kilogram of higher birth weight, age adjusted hazard ratios from prospective analysis were 0.77 (95% confidence interval 0.69 to 0.87) for coronary heart disease and 0.89 (0.78 to 1.01) for total stroke. In combined prospective and retrospective analysis, hazard ratios were 0.84 (0.76 to 0.93) for total stroke, 0.83 (0.71 to 0.96) for ischaemic stroke, and 0.86 (0.66 to 1.11) for haemorrhagic stroke. Exclusion of macrosomic infants (> 4536 g) yielded stronger estimates. Risk of coronary heart disease was especially high for women who crossed from a low centile of weight at birth to a high centile of body mass index in adulthood. The association of lower birth weight with increased risk of stroke was apparent across categories of body mass index in adults and was not especially strong among heavier women.

CONCLUSIONS

Higher body mass index in adulthood is an especially strong risk factor for coronary heart disease among women who were small at birth. In this large cohort of women, size at birth and adiposity in adulthood interacted to predict events of coronary heart disease but not stroke events.

Developmental origins of the metabolic syndrome: prediction, plasticity, and programming

The "fetal" or "early" origins of adult disease hypothesis was originally put forward by David Barker and colleagues and stated that environmental factors, particularly nutrition, act in early life to program the risks for adverse health outcomes in adult life. This hypothesis has been supported by a worldwide series of epidemiological studies that have provided evidence for the association between the perturbation of the early nutritional environment and the major risk factors (hypertension, insulin resistance, and obesity) for cardiovascular disease, diabetes, and the metabolic syndrome in adult life. It is also clear from experimental studies that a range of molecular, cellular, metabolic, neuroendocrine, and physiological adaptations to changes in the early nutritional environment result in a permanent alteration of the developmental pattern of cellular proliferation and differentiation in key tissue and organ systems that result in pathological consequences in adult life. This review focuses on those experimental studies that have investigated the critical windows during which perturbations of the intrauterine environment have major effects, the nature of the epigenetic, structural, and functional adaptive responses which result in a permanent programming of cardiovascular and metabolic function, and the role of the interaction between the pre- and postnatal environment in determining final health outcomes.

A review of low birth weight: predictors, precursors and morbidity outcomes

This paper reviews the global evidence concerning infant low birth weight (LBW) (2.500kg and below) in relation to suggested causative factors, such as undernutrition, stress, smoking, drug abuse and deprived living environments. In addition, health promotion strategies in place to reduce LBW incidence in both developed and underdeveloped countries are reviewed. The paper also focuses on the high incidence of LBW in the UK in comparison to other European and developed countries. Predictors of LBW are then considered comparing findings of a study conducted in the UK with findings in underdeveloped countries. In addition, LBW risk is discussed in the context of vulnerability factors, such as teen pregnancy, child abuse and domestic violence. In conclusion, the author argues for a health promotion policy in the UK to reduce incidence of LBW in areas of deprivation and suggests that the improvement of maternal health is key in improving the health of today's infants and children who will one day become the adults of tomorrow.

Dutch women with a low birth weight have an increased risk of myocardial infarction later in life: a case control study

Background

To investigate whether low birth weight increases the risk of myocardial infarction later in life in women.

Methods

Nationwide population-based case-control study. Patients and controls: 152 patients with a first myocardial infarction before the age of 50 years in the Netherlands. 568 control women who had not had a myocardial infarction stratified for age, calendar year of the index event, and area of residence.

Results

Birth weight in the patient group was significantly lower than in control women (3214 vs. 3370 gram, mean difference -156.3 gram (95%CI -9.5 to -303.1). The odds ratio for myocardial infarction, associated with a birth weight lower than 3000 gram (20^th percentile in controls) compared to higher than 3000 gram was 1.7 (95%CI 1.1–2.7), while the odds ratio for myocardial infarction for children with a low birth weight (< 2000 g) compared to a birth weight ≥ 2000 g was 2.4 (95%CI 1.0 – 5.8). Both figures did not change after adjustment for putative confounders (age, education level, body mass index, waist-hip ratio, hypertension, diabetes, hypercholesterolemia, smoking, and family history of cardiovascular disease).

Conclusions

Low birth weight is associated with an increased risk of myocardial infarction before age of 50 in Dutch women.

Diet during pregnancy, neonatal outcomes and later health

Renewed interest in nutrition during pregnancy has been generated by the hypothesis that adult disease has origins in early life. Animal experiments clearly show that altering maternal diet before and during pregnancy can induce permanent changes in the offspring’s birth size, adult health and lifespan. Among women living in Western societies, cigarette smoking is the most important factor known to reduce fetal growth, followed by low pre-pregnancy weight and low gestational weight gain. Obesity is also associated with pregnancy complications and adverse neonatal outcomes, so inadequate or excessive energy intake is not optimal for the developing fetus. Against a history of inconsistent results, several recent studies suggest that in Western settings the balance of macronutrients in a woman’s diet can influence newborn size. Effects appear to be modest, but this relationship may not encapsulate the full significance for health of the child, as there is emerging evidence of associations with long-term metabolic functioning that are independent of birth size. Consequences of inadequate maternal nutrition, for the offspring, may depend on timing during gestation, reflecting critical windows for fetal development. Where women are not malnourished, changing a woman’s nutritional plane during pregnancy may be detrimental to the unborn baby, and systematic reviews of the literature on dietary supplementation during pregnancy indicate few benefits and possible risks. In view of this, improved diet before pregnancy deserves greater attention.

Can we generalise from findings in twins?

A number of recent studies have used data from twins to shed light on the causal pathways underlying the observed association between birthweight and cardiovascular risk factors or coronary heart disease. The issue of whether findings from twin studies are generally informative, or whether factors associated with twinning preclude generalisation, is considered here. It is concluded that the association between birthweight and later health may differ quantitatively between twins and singletons, but evidence regarding blood pressure suggests it may not differ qualitatively. However, more information is needed on a number of gestational and maternal factors, and on measures of health other than blood pressure. Placentation and issues relating to infertility and its treatment need to be recorded and, together with gestation length, may need to be taken into account in analyses.

The impact of birth weight on coronary heart disease morbidity and mortality in a birth cohort followed up for 85 years: a population-based study of men born in 1913

OBJECTIVES

To analyse whether there is a relationship between birth weight on the one hand and coronary heart disease (CHD) and cardiovascular disease (CVD) mortality and morbidity on the other, whether such a relationship is influenced by potential modifying factors from the time of birth, adult height and the presence of diabetes, and what significance these possible associations might have for the CHD and CVD rates in the general population.

DESIGN

Population-based birth cohort.

SETTING

Sweden.

SUBJECTS

A total of 1319 singleton men born in 1913, surviving until age 20 and from then on followed until 85 years of age.

MAIN OUTCOME MEASURES

CHD and CVD mortality and morbidity events.

RESULTS

The gestational age adjusted CHD and CVD mortality and morbidity hazard ratios were virtually unaffected by birth weight. Taking possible effect-modifying variables into account did not change the results. The population attributable risk percentage for CHD and CVD mortality and morbidity due to a birth weight <or=3000 g was 1% or less.

CONCLUSIONS

Birth weight did not significantly affect CHD or CVD mortality or morbidity. A birth weight <or=3000 g contributes little to the burden of CHD and CVD on a community level.

The body mass index is a less-sensitive tool for detecting cases with obesity-associated co-morbidities in short stature subjects

OBJECTIVE

To assess the ability of the body mass index (BMI) to detect obesity-associated morbidity in subjects with a normal or short stature.

METHODS

Information was obtained on 119 975 subjects from a cardiovascular risk factors detection program. Standardized questionnaires were used. Capillary glucose and cholesterol concentrations were measured. Diabetes, arterial hypertension and hypercholesterolemia were selected as end points. Sensitivity, specificity and the likelihood ratio for several BMI thresholds were calculated. ROC curves were constructed to identify the BMI cutoff points with best diagnostic performance. The area under the curve (AUC) was used to assess the proficiency of BMI.

RESULTS

Short stature (height </=150 cm for women or </=160 cm for men) was found in 24 854 subjects (20.7%). These cases had a higher prevalence of type II diabetes and arterial hypertension even after adjusting for confounding variables. In addition, the frequency of the abnormalities was higher even at the lowest BMI values; the prevalence increased in direct proportion with the BMI, but at a lower rate compared to cases with normal stature. The AUC for every co-morbidity was smaller in short stature subjects. The likelihood ratio for detecting co-morbidities increased at the same BMI value in subjects with or without short stature.

CONCLUSIONS

The prevalence of obesity-associated co-morbidities is higher in subjects with short stature compared to those without it. The proficiency of BMI as a diagnostic tool is poor in short stature subjects. This problem is not resolved by decreasing BMI thresholds used to define overweight.

Early Malnutrition and Metabolic Abnormalities Later in Life

Early malnutrition has been significantly associated with chronic diseases later in life. The finding of metabolic abnormalities in individuals with malnutrition in fetal life and early in postnatal life may have important public health implications in developing countries, although only a few studies have examined the relationship between body weight at the first year of life and later metabolic abnormalities. We assessed the effects of malnutrition during the first year of life (independent of birth weight) on several metabolic parameters in young men. The areas under the curves of glucose and insulin were significantly higher in 52 individuals with a history of malnutrition during the first year of life (cases) than in controls. An insulin sensitivity index was derived and was lower in cases than in controls. In cases, the insulin sensitivity index worsened as body mass index (BMI) increased within the normal range of BMI. A euglycemic insulin clamp as well as an abdominal CT scan were performed in 26 cases and 27 controls. Higher levels of abdominal adipose tissue were more detrimental to insulin sensitivity in previously malnourished individuals. This study suggests that metabolic programming early in life is not restricted to intrauterine growth. We conclude that early malnutrition in extrauterine life independent of birth weight has an adverse effect on insulin sensitivity, glucose tolerance, and lipid profile in young men. This appears to worsen as body mass index increases, even within "normal" limits.

Differential association of birth weight with cardiovascular risk variables in African-Americans and Whites: the Bogalusa heart study

PURPOSE

To study the relationship between low birth weight and the subsequent development of cardiovascular risk factors and to compare this relationship between African-Americans and whites at 7 to 21 years of age.

METHODS

The relationship of birth weight with cardiovascular risk factors, namely, systolic and diastolic blood pressure (BP), BMI, HDL, LDL, triglycerides, and HOMA insulin resistance (HOMA-IR) was examined retrospectively using information on 1155 participants (730 whites and 425 African-Americans) from two cohorts of the Bogalusa Heart Study.

RESULTS

Participants with lower birth weight had higher systolic BP, HOMA-IR, triglycerides, and LDL. The association of birth weight with LDL, triglycerides, and HOMA-IR was stronger in African-Americans, while the association with systolic BP was stronger in whites. Subjects with birth weight <2500 g were at increased risk of having values of HOMA-IR and LDL in the upper quartile of the observed range compared with those with birth weight >2500 g.

CONCLUSIONS

These results support a relationship between low birth weight and the later development of important cardiovascular risk factors in young African-Americans and white individuals. This relationship tends to be stronger in African-Americans than in whites, except for systolic blood pressure.

Birth weight and cardiovascular risk factors in a cohort followed until 80 years of age: the study of men born in 1913

OBJECTIVES

To analyse whether there is a relation-ship between birth weight and cardiovascular risk factors given the influence of potential modifying factors from birth time, former generations and adult life.

DESIGN

Population-based cohort followed until 80 years of age.

SETTING

Sweden.

SUBJECTS

A total of 478 singleton men born in 1913 and participating in a population study in Gothenburg, Sweden, from age 50.

MAIN OUTCOME MEASURES

Systolic blood pressure (SBP), antihypertensive treatment, incident diabetes mellitus, and serum total cholesterol, serum triglycerides and waist circumference as both continuous variables and in the highest quintiles of their distributions.

RESULTS

After adjustment for the influence of birth time variables, hereditary factors and anthropometric and socio-economic adult life variables, SBP decreased by 3.7 mmHg per 1000 g increase of birth weight, the prevalence of antihypertensive treatment decreased by 32%, diabetes decreased by 53%, serum total cholesterol decreased by 0.20 mmol L(-1) and being in the top quintile of serum cholesterol decreased by 23%. The population risk percentage due to a birth weight < or =3000 g was for all three outcomes 3.8% and for antihypertensive treatment, diabetes and cholesterol 0.2, 18 and 2.5%, respectively.

CONCLUSIONS

Low birth weight thus seems to affect the development of increasing SBP, antihypertensive treatment, diabetes and high cholesterol even when potential effect modifiers from birth time, former generations and adult life were taken into account. In the general population, the risk percentage due to a birth weight < or =3000 g was largest for diabetes.

Birthweight and relationship with infant, child and adult mortality in the Jerusalem perinatal study

There is growing evidence that several chronic adult diseases, such as coronary heart disease and stroke, can result from events occurring in fetal life. The aim of this study was to examine the relation between birthweight and all-cause mortality in young adults. We studied total mortality in a population-based cohort of 80 936 offspring born in Jerusalem in 1964-76. During an average follow-up of 28.8 years 2 324 984 person-years were contributed and 2092 deaths occurred. Overall, in both genders, the univariable and the multivariable Cox-proportional hazard models indicated a strong negative relationship between birthweight and total mortality, mostly because of infant deaths. At ages 1-14 birthweight seemed unrelated to all-cause mortality. In males aged 15+, birthweight was again a significant predictor of death (Hazard ratio (HR) = 0.88, 95% confidence interval (CI) [0.78, 0.99], for 1 standard deviation (SD) increase in birthweight). The analysis by categories suggested a general decreasing of the risk of mortality with increasing birthweight (HRs = 1.0, 1.02, 0.85, 0.77, 0.57 for those belonging to birthweight groups of < 2500 g, 2500-2999 g, 3000-3499 g, 3500-3999 g and > or = 4000 g, respectively). In females aged 15+ there was a J-shaped relation between birthweight and mortality but these associations were not statistically significant. These findings add to a growing body of evidence that events during intrauterine life have remote consequences for adult health and underline the need to consider gender differences.

Relationship between birthweight and blood lipid concentrations in later life: evidence from the existing literature

BACKGROUND

It has been suggested that there is a link between fetal growth and chronic diseases later in life. Several studies have shown a negative association between birthweight and cardiovascular diseases, as well as cardiovascular disease risk factors, such as blood pressure and type 2 diabetes. Far fewer studies have focused on the association between size at birth and blood lipid concentrations. We have conducted a qualitative assessment of the direction and consistency of the relationship between size at birth and blood lipid concentrations to see whether the suggested relationship between intrauterine growth and cardiovascular diseases is mediated by lipid metabolism.

METHODS

A literature search covering the period January 1966 to January 2003 was performed using Medline, Embase, and Web of Science. All papers written in English and reporting the relationship between size at birth and lipid levels in humans were assessed. Bibliographies were searched for further publications.

RESULTS

From an initial screen of 1198 references, 39 papers were included involving 28 578 individuals. There was no consistent relationship between size at birth and blood lipid levels; the one exception being triglyceride concentration, which showed statistically significant negative or U-shaped, but not positive, relationships with birthweight.

CONCLUSION

This review does not strongly support a link between birthweight and blood lipid levels in later life. However, the research in this area is limited and in order to make any definitive conclusions, longitudinal studies with sufficient power, data, and prospective follow-up are needed.

Effect of malnutrition during the first year of life on adult plasma insulin and glucose tolerance

There is evidence linking intrauterine growth retardation with increased cardiovascular risk and diabetes mellitus (DM) later in life. However, little is known about the association between malnutrition during the first year of life and metabolic abnormalities in adulthood. The objective of this study was to assess the effect of documented malnutrition during the first year of life on glucose tolerance, plasma insulin, lipid profile, and blood pressure in early adulthood, as well as to assess the interaction between body mass index (BMI) and malnutrition on these variables. A study group of young men with a documented history of malnutrition during their first year of life was recruited from 4 pediatric hospitals in Mexico City and compared with a control group. Subjects included were 52 men, aged 20.2 +/- 3.6 years, with a mean birth weight of 3.0 +/- 0.7 kg and documented malnutrition in their first year of life; controls were 50 men, aged 23.3 +/- 1.8 years, with a mean birth weight of 3.2 +/- 0.5 kg. Insulin and glucose concentrations, fasting and in response to an oral glucose load, plasma lipids, blood pressure, and an insulin sensitivity index (ISI) were measured. The areas under the curves of glucose (AUCG) and insulin (AUCI) were significantly higher in cases (P =.012 and <.002, respectively), independent of birth weight, BMI, or age. BMI was significantly associated with fasting plasma insulin (FPI), AUCI, ISI, triglyceride, and high-density lipoprotein (HDL)-cholesterol concentrations in cases, but not in controls. These data suggest that early malnutrition in extrauterine life, independently of birth weight, has an adverse effect on insulin metabolism and glucose tolerance in young men, and it worsens as body mass increases even within the normal range of BMI. Therefore, it is advisable to prevent obesity in individuals exposed to early malnutrition.

Nutrition before birth, programming and the perpetuation of social inequalities in health

The need to explain social inequalities in health has led to the theory that chronic disease is due, in part, to a legacy of adverse experiences in early life. Epidemiological studies show consistently that individuals who are small at birth have an increased risk of cardiovascular disease in adulthood. There is growing consensus that this association reflects a causal relationship and is not simply the product of bias or confounding. The concept of programming is invoked as the biological mechanism; birth size is thus a proxy for fetal programming. Recent findings suggest that fetal programming interacts with the post-birth environment. The adverse exposures that are thought to underlie and potentiate programming cluster in socially patterned ways, thus creating substantial inequalities in health. Experiments in animals demonstrate that nutritional interventions before or during pregnancy can produce programming phenomena in the offspring, sometimes without an impact on birth size. However, the extent to which maternal nutrition contributes to programming in contemporary developed countries is uncertain.

Low gestational age associated with abnormal retinal vascularization and increased blood pressure in adult women

The objective was to investigate any possible relationship between functional and structural vascular changes in women with low gestational age and/or low birth weight by analyzing the retinal vascular pattern in women with thoroughly documented blood pressure. Retinal vessel morphology was evaluated by digital image analysis of ocular fundus photographs in 47 subjects, aged 23-30 y. The women were allocated into three groups: 1) those born preterm and appropriate for gestational age (AGA), with a median gestational age at birth of 30 wk and a median birth weight of 1250 g (n = 14); 2) those born small for gestational age (SGA) but full term (median 40 wk), with a median birth weight of 2130 g (n = 17), and 3) those born full term, AGA, and with a median birth weight of 3640 g (n = 16). Women born preterm had significantly higher length index for arterioles compared with the other two groups (median 1.11 and 1.08, respectively, p = 0.005). In addition, the preterm-born women had significantly fewer number of vascular branching points compared with the controls (median 27 and 30, respectively, p = 0.03). The abnormal retinal vascularization observed in ex-preterm women together with an increased casual blood pressure observed in these subjects suggests that being born preterm does have effects on the vascular system that persist into adult life. In addition, it demonstrates that preterm birth seems to affect the vascular system both functionally and structurally, which, in adulthood, could result in a lower threshold for the development of vascular disease.