Diet in pregnancy and the offspring's blood pressure 40 years later

Variable placental thickness affects placental functional efficiency independent of other placental shape abnormalities

Our previous work suggests that stressors that impact placental vascular growth result in a deformed chorionic surface shape, which reflects an abnormal placental three-dimensional shape. We propose to use variability of placental disk thickness as a reflector of deviations in placental vascular growth at the finer level of the fetal stems. We hypothesize that increased variability of thickness is associated with abnormal chorionic surface shape, but will be a predictor of reduced placental functional efficiency (smaller baby for a given placental weight) independent of shape. These measures may shed light on the mechanisms linking placental growth to risk of adult disease. The sample was drawn from the Pregnancy, Infection and Nutrition Study. In all, 94.6% of the cohort consented to placental examination. Of the 1023 delivered at term, those previously sectioned by the Pathology Department were excluded, leaving 587 (57%) cases with intact placentas that were sliced and photographed. The chorionic surface shape and the shape of a central randomly oriented placental slice were analyzed and measures were compared using correlation. Lower mean placental disk thickness and more variable disk thickness were each strongly and significantly correlated with deformed chorionic plate shapes. More variable disk thickness was strongly correlated with reduced placental efficiency independent of abnormal chorionic surface shape. Variability of placental disk thickness, simple to measure in a single randomly oriented central slice, may be an easily acquired measure that is an independent indicator of lowered placental efficiency, which may in turn program the infant and result in increased risk for development of adult diseases.

Placental programming of blood pressure in Indian children

Aim

To determine whether the size and shape of the placental surface predict blood pressure in childhood.

Methods

We studied blood pressure in 471 nine-year-old Indian children whose placental length, breadth and weight were measured in a prospective birth cohort study.

Results

In the daughters of short mothers (<median height), systolic blood pressure (SBP) rose as placental breadth increased (β = 0.69 mmHg/cm, p = 0.05) and as the ratio of placental surface area to birthweight increased (p = 0.0003). In the daughters of tall mothers, SBP rose as the difference between placental length and breadth increased (β = 1.40 mmHg/cm, p = 0.007), that is as the surface became more oval. Among boys, associations with placental size were only statistically significant after adjusting for current BMI and height. After adjustment, SBP rose as placental breadth, area and weight decreased (for breadth β = −0.68 mmHg/cm, p < 0.05 for all three measurements).

Conclusions

The size and shape of the placental surface predict childhood blood pressure. Blood pressure may be programmed by variation in the normal processes of placentation: these include implantation, expansion of the chorionic surface in mid-gestation and compensatory expansion of the chorionic surface in late gestation.

Evidence for developmental programming of cerebral laterality in humans

Adverse fetal environments are associated with depression, reduced cognitive ability and increased stress responsiveness in later life, but underlying mechanisms are unknown. Environmental pressures on the fetus, resulting from variations in placental function and maternal nutrition, health and stress might alter neurodevelopment, promoting the development of some brain regions over others. As asymmetry of cerebral activity, with greater right hemisphere activity, has been associated with psychopathology, we hypothesized that regional specialization during fetal life might be reflected persistently in the relative activity of the cerebral hemispheres. We tested this hypothesis in 140 healthy 8-9 year-old children, using tympanic membrane temperature to assess relative blood flow to the cerebral hemispheres at rest and following psychosocial stress (Trier Social Stress Test for Children). Their birth weight and placental weight had already been measured when their mothers took part in a previous study of pregnancy outcomes. We found that children who had a smaller weight at birth had evidence of greater blood flow to the right hemisphere than to the left hemisphere (r = -.09, P = .29 at rest; r = -.18, P = .04 following stress). This finding was strengthened if the children had a relatively low birth weight for their placental weight (r = -.17, P = .05 at rest; r = -.31, P = .0005 following stress). Our findings suggest that lateralization of cerebral activity is influenced persistently by early developmental experiences, with possible consequences for long-term neurocognitive function.

Evidence that prenatal programming of hypertension by dietary protein deprivation is mediated by fetal glucocorticoid exposure

BACKGROUND

Prenatal programming by maternal dietary protein deprivation and prenatal dexamethasone result in a reduction in nephron number and hypertension when the offspring are studied as adults.

METHODS

To determine whether prenatal dietary protein deprivation results in a reduction in nephron number and hypertension in offspring by exposure to maternal glucocorticoids, we administered metyrapone to rats fed either a 6% or 20% protein diet to inhibit glucocorticoid production and compared the offspring to rats that were the product of mothers fed either a 6% or 20% protein diet during the last half of pregnancy.

RESULTS

Male offspring from the 6% group had elevated systolic blood pressure (149 ± 2 vs. 130 ± 5 mm Hg, P < 0.05) and a reduction in glomeruli compared to the 20% group (22,111 ± 627 vs. 29,666 ± 654 glomeruli/kidney, P < 0.001). Maternal metyrapone administration did not affect the blood pressure in the 20% group but ameliorated the increase in blood pressure in the 6% male group to values comparable to the 20% control group (138 ± 6 vs. 130 ± 5 mm Hg). Male offspring of the 6% group that received metyrapone had an increase in the number of glomeruli compared to the vehicle-treated 6% group (26,780 ± 377 vs. 22,111 ± 627 glomeruli/kidney, P < 0.001), but less glomeruli compared to the 20% protein control group (26,780 ± 377 vs. 29,666 ± 654 glomeruli/kidney, P = 0.01).

CONCLUSIONS

The reduction in nephron number and hypertension induced by maternal protein deprivation in male offspring is ameliorated by inhibition of glucocorticoid production.

Metabolic imprinting, programming and epigenetics – a review of present priorities and future opportunities

Metabolic programming and metabolic imprinting describe early life events, which impact upon on later physiological outcomes. Despite the increasing numbers of papers and studies, the distinction between metabolic programming and metabolic imprinting remains confusing. The former can be defined as a dynamic process whose effects are dependent upon a critical window(s) while the latter can be more strictly associated with imprinting at the genomic level. The clinical end points associated with these phenomena can sometimes be mechanistically explicable in terms of gene expression mediated by epigenetics. The predictivity of outcomes depends on determining if there is causality or association in the context of both early dietary exposure and future health parameters. The use of biomarkers is a key aspect of determining the predictability of later outcome, and the strengths of particular types of biomarkers need to be determined. It has become clear that several important health endpoints are impacted upon by metabolic programming/imprinting. These include the link between perinatal nutrition, nutritional epigenetics and programming at an early developmental stage and its link to a range of future health risks such as CVD and diabetes. In some cases, the evidence base remains patchy and associative, while in others, a more direct causality between early nutrition and later health is clear. In addition, it is also essential to acknowledge the communication to consumers, industry, health care providers, policy-making bodies as well as to the scientific community. In this way, both programming and, eventually, reprogramming can become effective tools to improve health through dietary intervention at specific developmental points.

Changes in placental size during Ramadan

BACKGROUND

Placental growth responds to maternal influences. Ramadan is an annual period of day-time fasting during which people in Saudi Arabia, including pregnant women, change their diets and physical activity. Little is known about the effects of this altered lifestyle on placental development.

METHODS

We studied the birth records of 7083 babies born over a four-year period to Saudi nationals in Unizah, a small city 350km to the north of Riyadh, the capital city of Saudi Arabia. The records included birth weight, placental weight and gestational age.

RESULTS

Mean birth weight was similar to European values but the mean placental weight and ratio of placental weight to birth weight were lower. Among babies who were in the second or third trimester of gestation during Ramadan the mean placental weight and ratio were below those of babies who were not in utero during Ramadan. Among boys the mean placental ratios were 14.4 percent (second trimester) and 14.5 percent (third trimester) compared with 14.9 percent (p=<0.001 and 0.002). The corresponding figures for girls were 14.8 and 14.6 percent compared with 15.1 percent (p=0.02 and <0.001).

CONCLUSIONS

In Saudi Arabia placentas respond to mothers' limited ability to deliver nutrients to them. Placental growth slows but efficiency is increased so that fetal growth is sustained, albeit with a reduced reserve capacity. The lifestyle changes associated with Ramadan further slow placental growth. Ramadan may influence placental growth through dietary changes other than day-time fasting. Changes in placental growth during Ramadan could be associated with altered fetal programming, and may therefore have long-term implications for the health of the next generation.

The surface area of the placenta and hypertension in the offspring in later life

Hypertension is more common among people who had low birthweight. Birthweight depends on the mothers body size and on the growth of the placenta. We studied a group of 2003 subjects, of whom 644 were being treated for hypertension. They were born during 1934-44 in a hospital that kept detailed records of maternal and placental size. Hypertension was associated with reduced placental weight and surface area. These associations were strongest in the offspring of mothers with below average height or low socioeconomic status. In people whose mothers had below average height (160 cm) the prevalence of hypertension fell from 38% if the placental area was 200 cm(2) or less to 21% if the area was more than 320 cm(2) (p=0.0007). In the offspring of tall, middle class mothers, who were likely to have been the best nourished, hypertension was predicted by large placental weight in relation to birthweight. The odds ratio rose from 1.0 if the ratio of placental weight to birthweight was 0.17 or less to 1.9 (95% confidence interval 0.8 to 5.0) if the ratio was more than 0.21 (p for trend =0.03). We conclude that the effects of placental area on hypertension depend on the mothers nutritional state. Poor maternal nutrition may compound the adverse effects of small placental size. In better-nourished mothers the placental surface may expand to compensate for fetal undernutrition. Growth along the minor axis of the surface may be more nutritionally sensitive than growth along the major axis.

Non-linear and gender-specific relationships among placental growth measures and the fetoplacental weight ratio

GOALS

Fetal growth depends on placental growth; the fetoplacental weight ratio (FPR) is a common proxy for the balance between fetal and placental growth. Male and female infants are known to have differing vulnerabilities in fetal life, during parturition and in infancy. We hypothesized that these differences may be paralleled by differences in how birth weight (BW) and the fetoplacental weight ratio (FPR) are affected by changes in placental proportions.

MATERIALS AND METHODS

Placental proportion measures (disk shape, larger and smaller chorionic diameters, chorionic plate area calculated as the area of an ellipse with the 2 given diameters, disk thickness, cord eccentricity and cord length) were available for 24,601 participants in the Collaborative Perinatal Project delivered between >34 and <43 completed weeks. The variables were standardized and entered into multiple automated regression splines (MARS 2.0, Salford Systems, Vista CA) to identify nonlinearities in the relationships of placental growth measures to BW and FPR with results compared for male and female infants.

RESULTS

Changes in chorionic plate growth in female compared to male infants resulted in a greater change in BW and FPR. The positive effects of umbilical cord length on BW reversed at the mean umbilical cord length in females and at +0.08 SD in male infants.

CONCLUSIONS

Female infants' BW and FPR are each more responsive to changes in placental chorionic plate growth dimensions than males; this may account for greater female resilience (and greater male vulnerability) to gestational stressors. The effect of umbilical cord length on FPR may be due to longer cords carrying greater fetal vascular resistance. Again male fetuses show a higher "threshold" to the negative effects of longer cords on FPR.

Feeding pregnant rats a low-protein diet alters the hepatic expression of SREBP-1c in their offspring via a glucocorticoid-related mechanism

Prenatal exposure to a low-protein diet programmes altered expression of genes that regulate lipid metabolism, including SREBP-1c. The main aim of this study was to investigate whether programmed changes to hepatic SREBP-1c expression in the rat are glucocorticoid-dependent. Rats were fed isocaloric diets (control or low-protein) throughout pregnancy. The low-protein group received 11beta-hydroxylase inhibitor, the inhibitor plus corticosterone, or vehicle injections over the first 2 weeks of pregnancy. The control group was administered vehicle injections only. On delivery the animals were transferred to a standard chow diet. The offspring were weaned at 4 weeks of age on to the same chow diet and killed for collection of liver tissue. The inhibitor of glucocorticoid synthesis reversed the suppressive effect of low-protein diet on hepatic SREBP-1c expression of both protein and mRNA seen in low-protein exposed offspring. To test if this effect is through direct effect on the SREBP-1c promoter, H4IIE cells were transfected with a luciferase reporter construct controlled by the SREBP-1c promoter treated with dexamethasone. Dexamethasone induced the expression of SREBP-1c in vitro. Together these studies demonstrate that foetal over-exposure to glucocorticoids, through indirect mechanism, play a crucial role in low-protein-diet-induced changes in lipid metabolism regulating genes.

Role of the kidney in the prenatal and early postnatal programming of hypertension

Epidemiologic studies from several different populations have demonstrated that prenatal insults, which adversely affect fetal growth, result in an increased incidence of hypertension when the offspring reaches adulthood. It is now becoming evident that low-birth-weight infants are also at increased risk for chronic kidney disease. To determine how prenatal insults result in hypertension and chronic kidney disease, investigators have used animal models that mimic the adverse events that occur in pregnant women, such as dietary protein or total caloric deprivation, uteroplacental insufficiency, and prenatal administration of glucocorticoids. This review examines the role of the kidney in generating and maintaining an increase in blood pressure in these animal models. This review also discusses how early postnatal adverse events may have repercussions in later life. Causes for the increase in blood pressure by perinatal insults are likely multifactorial and involve a reduction in nephron number, dysregulation of the systemic and intrarenal renin-angiotensin system, increased renal sympathetic nerve activity, and increased tubular sodium transport. Understanding the mechanism for the increase in blood pressure and renal injury resulting from prenatal insults may lead to therapies that prevent hypertension and the development of chronic kidney and cardiovascular disease.

Animal models for the study of the developmental origins of health and disease

Human epidemiological studies have indicated that the risk of developing non-communicable diseases in later life may be related to exposures during the developmental period. Developmental life is a vulnerable period of the lifespan during which adverse environmental factors have the potential to disturb the processes of cell proliferation and differentiation or to alter patterns of epigenetic remodelling. Animal models have been instrumental in demonstrating the biological plausibility of the associations observed in human populations, providing proof of principle to the theory of the developmental origins of health and disease (DOHaD). A variety of large- and small-animal models have made important contributions to the field, providing strong evidence of a causal relationship between early-life exposures and metabolic risk factors in later life. Studies of animal models are continuing to contribute to improving the understanding of the mechanisms of the developmental origins of disease. All models have their advantages and disadvantages, and the model that is most appropriate for any particular study is hypotheses dependent. The present review aims to briefly summarise the contributions that animal models have made to the DOHaD field, before reviewing the strengths and weaknesses of these animal models. It is proposed that the integration of evidence from a variety of different models is required for the advancement of understanding within the field.

Gross placental measures and childhood growth

OBJECTIVES

We hypothesised that the gross placental measures would be positively associated with childhood growth.

METHODS

We analysed data on 23,967 mother-infant pairs enrolled in the Collaborative Perinatal Project. In race-stratified regression models, the main outcomes were birthweight and z-score body-mass index (BMI) at ages 4 and 7.

RESULTS

Some placental measures were significantly associated with z-score BMI at age 7: in Blacks, placental weight (beta = 0.0004/g; 95%CI: 0.0001, 0.0008), chorionic plate area (beta = 0.0007; 95%CI: 0.0001, 0.0012) and largest diameter (beta = 0.013; 95%CI: 0.004, 0.026); and in Whites placental weight (beta = 0.0004/g; 95%CI: 0.0001, 0.0003) and largest diameter (Model 3: beta = 0.020; 95%CI: 0.007, 0.032). Tested as group, placental measures significantly predicted z-score BMI at age 7 (all p values < 0.005).

CONCLUSIONS

Placental structure independently predicts birthweight and childhood growth. Strategies to improve placental structure might favourably influence birthweight and childhood development.

Placental weight and placental weight-to-birth weight ratio are increased in diet- and exercise-treated gestational diabetes mellitus subjects but not in subjects with one abnormal value on 100-g oral glucose tolerance test

The aim of the present study was to determine whether the placental weight and placental weight-to-birth weight ratio (PW/BW) increased in pregnant women with one abnormal value (OAV) on 100-g oral glucose tolerance test (OGTT) and diet- and exercise-treated, non-insulin-requiring gestational diabetes mellitus (GDM) subjects. The 50-g glucose challenge test (GCT) was administered to 324 pregnant women. Women with abnormal 50-g test received a 100-g, 3-h OGTT using National Diabetes Data Group criteria. Women with GDM and OAV were treated with diet and exercise. Twenty subjects who required insulin or met exclusion criteria were excluded from the study. After the exclusion of 20 subjects, the GDM group consisted of 30 (9.7%) pregnant women and the OAV group consisted of 32 (9.9%) pregnant women. The control group consisted of 242 pregnant women. Birth weight (GDM: 3288.3+/-364.2 g; OAV: 3278.1+/-409.9 g; control group: 3270.6+/-346.5 g) did not differ significantly between groups (P>.05). Significantly higher placental weights (GDM: 694.8+/-152.1 g; OAV: 622.2+/-105.3 g; control group: 610.2+/-116.6 g; P<.01) and PW/BW (GDM: 0.21+/-0.03; OAV: 0.193+/-0.04; control group: 0.188+/-0.04; P<.01) were observed in GDM group compared to OAV and control group. No significant difference was found for OAV group in terms of placental weight and PW/BW compared to the control group. Our data indicated that women with OAV delivered infants and placenta of similar weight to those of normal pregnancies.

Nutritional programming of disease: unravelling the mechanism

Nutritional programming is the process through which variation in the quality or quantity of nutrients consumed during pregnancy exerts permanent effects upon the developing fetus. Programming of fetal development is considered to be an important risk factor for non-communicable diseases of adulthood, including coronary heart disease and other disorders related to insulin resistance. The study of programming in relation to disease processes has been advanced by development of animal models, which have utilized restriction or over-feeding of specific nutrients in either rodents or sheep. These consistently demonstrate the biological plausibility of the nutritional programming hypothesis and, importantly, provide tools with which to examine the mechanisms through which programming may occur. Studies of animals subject to undernutrition in utero generally exhibit changes in the structure of key organs such as the kidney, heart and brain. These appear consistent with remodelling of development, associated with disruption of cellular proliferation and differentiation. Whilst the causal pathways which extend from this tissue remodelling to disease can be easily understood, the processes which lead to this disordered organ development are poorly defined. Even minor variation in maternal nutritional status is capable of producing important shifts in the fetal environment. It is suggested that these environmental changes are associated with altered expression of key genes, which are responsible for driving the tissue remodelling response and future disease risk. Nutrition-related factors may drive these processes by disturbing placental function, including control of materno-fetal endocrine exchanges, or the epigenetic regulation of gene expression.

Non-communicable diseases in low- and middle-income countries: context, determinants and health policy

The rise of non-communicable diseases and their impact in low- and middle-income countries has gained increased attention in recent years. However, the explanation for this rise is mostly an extrapolation from the history of high-income countries whose experience differed from the development processes affecting today's low- and middle-income countries. This review appraises these differences in context to gain a better understanding of the epidemic of non-communicable diseases in low- and middle-income countries. Theories of developmental and degenerative determinants of non-communicable diseases are discussed to provide strong evidence for a causally informed approach to prevention. Health policies for non-communicable diseases are considered in terms of interventions to reduce population risk and individual susceptibility and the research needs for low- and middle-income countries are discussed. Finally, the need for health system reform to strengthen primary care is highlighted as a major policy to reduce the toll of this rising epidemic.

Modifiable maternal exposures and offspring blood pressure: a review of epidemiological studies of maternal age, diet, and smoking

Prenatal programming of adult disease is well established in animals. In humans the impact of common in utero exposures on long-term offspring health is less clear. We reviewed epidemiology studies of modifiable maternal exposures and offspring blood pressure (BP). Three maternal exposures were identified for review and meta-analyzed where possible: smoking during pregnancy, diet, and age at childbirth. Meta-analysis suggested there was a modest association between higher offspring BP and prenatal exposure to smoke (confounder-adjusted beta = 0.62 mm Hg, 95% confidence interval: 0.19-1.05, I = 16.4%). However, the level of confounder adjustment varied between studies, which in some studies attenuated the association to the null. There was no strong evidence that any component of maternal diet during pregnancy (maternal protein, energy, calcium, and various other nutrients) influences offspring BP. The results of studies of maternal age varied and there was strong evidence of heterogeneity in the pooled analysis. The association with maternal age, if present, was modest (confounder-adjusted beta = 0.09 mm Hg/y, 95% confidence interval: -0.03 to 0.21, I = 89.8%). In sum, there is little empirical evidence that the maternal exposures reviewed program offspring BP. Other components of offspring health may be more susceptible to effects of programming in utero.

Role of maternal glucocorticoid inducible kinase SGK1 in fetal programming of blood pressure in response to prenatal diet

Maternal stress and malnutrition modify intrauterine fetal development with impact on postnatal blood pressure, nutrient, water, and electrolyte metabolism. The present study explored the possible involvement of maternal serum- and glucocorticoid-inducible kinase (SGK)-1 in fetal programming of blood pressure. To this end, wild-type (sgk1(+/+)) male mice were mated with SGK1 knockout (sgk1(-/-)) female mice, and sgk1(-/-) males with sgk1(+/+) females, resulting in both cases in heterozygotic (sgk1(-/+)) offspring. Following prenatal protein restriction, the offspring of sgk1(+/+) mothers gained weight significantly slower and had significantly higher blood pressure after birth. Moreover, a sexual dimorphism was apparent in fasting blood glucose and plasma corticosterone concentrations, with higher levels in female offspring. In contrast, prenatal protein restriction of sgk1(-/-) mothers had no significant effect on postnatal weight gain, blood pressure, plasma glucose concentration, or corticosterone levels, irrespective of offspring sex. Plasma aldosterone concentration, urinary flow rates, and urinary excretions of Na(+) and K(+) were not significantly modified by either maternal genotype or nutritional manipulation. In conclusion, maternal signals mediated by SGK1 may play a decisive role in fetal programming of hypertension induced by prenatal protein restriction.

Constraints on food choices of women in the UK with lower educational attainment

OBJECTIVE

Women of lower educational attainment have less balanced and varied diets than women of higher educational attainment. The diets of women are vital to the long-term health of their offspring. The present study aimed to identify factors that influence the food choices of women with lower educational attainment and how women could be helped to improve those choices.

DESIGN

We conducted eight focus group discussions with women of lower educational attainment to identify these factors. We contrasted the results of these discussions with those from three focus group discussions with women of higher educational attainment.

SETTING

Southampton, UK.

SUBJECTS

Forty-two white Caucasian women of lower educational attainment and fourteen of higher educational attainment aged 18 to 44 years.

RESULTS

The dominant theme in discussions with women of lower educational attainment was their sense that they lacked control over food choices for themselves and their families. Partners and children exerted a high degree of control over which foods were bought and prepared. Women's perceptions of the cost of healthy food, the need to avoid waste, being trapped at home surrounded by opportunities to snack, and having limited skill and experience with food, all contributed to their sense they lacked control over their own and their family's food choices.

CONCLUSIONS

An intervention to improve the food choices of women with lower educational attainment needs to increase their sense of control over their diet and the foods they buy. This might include increasing their skills in food preparation.

Maternal and child undernutrition: consequences for adult health and human capital

In this paper we review the associations between maternal and child undernutrition with human capital and risk of adult diseases in low-income and middle-income countries. We analysed data from five long-standing prospective cohort studies from Brazil, Guatemala, India, the Philippines, and South Africa and noted that indices of maternal and child undernutrition (maternal height, birthweight, intrauterine growth restriction, and weight, height, and body-mass index at 2 years according to the new WHO growth standards) were related to adult outcomes (height, schooling, income or assets, offspring birthweight, body-mass index, glucose concentrations, blood pressure). We undertook systematic reviews of studies from low-income and middle-income countries for these outcomes and for indicators related to blood lipids, cardiovascular disease, lung and immune function, cancers, osteoporosis, and mental illness. Undernutrition was strongly associated, both in the review of published work and in new analyses, with shorter adult height, less schooling, reduced economic productivity, and--for women--lower offspring birthweight. Associations with adult disease indicators were not so clear-cut. Increased size at birth and in childhood were positively associated with adult body-mass index and to a lesser extent with blood pressure values, but not with blood glucose concentrations. In our new analyses and in published work, lower birthweight and undernutrition in childhood were risk factors for high glucose concentrations, blood pressure, and harmful lipid profiles once adult body-mass index and height were adjusted for, suggesting that rapid postnatal weight gain--especially after infancy--is linked to these conditions. The review of published works indicates that there is insufficient information about long-term changes in immune function, blood lipids, or osteoporosis indicators. Birthweight is positively associated with lung function and with the incidence of some cancers, and undernutrition could be associated with mental illness. We noted that height-for-age at 2 years was the best predictor of human capital and that undernutrition is associated with lower human capital. We conclude that damage suffered in early life leads to permanent impairment, and might also affect future generations. Its prevention will probably bring about important health, educational, and economic benefits. Chronic diseases are especially common in undernourished children who experience rapid weight gain after infancy.

Mechanisms underlying developmental programming of elevated blood pressure and vascular dysfunction: evidence from human studies and experimental animal models

Cardiovascular-related diseases are the leading cause of death in the world in both men and women. In addition to the environmental and genetic factors, early life conditions are now also considered important contributing elements to these pathologies. The concept of 'fetal' or 'developmental' origins of adult diseases has received increased recognition over the last decade, yet the mechanism by which altered perinatal environment can lead to dysfunction mostly apparent in the adult are incompletely understood. This review will focus on the mechanisms and pathways that epidemiological studies and experimental models have revealed underlying the adult cardiovascular phenotype dictated by the perinatal experience, as well as the probable key causal or triggering elements. Programmed elevated blood pressure in the adult human or animal is characterized by vascular dysfunction and microvascular rarefaction. Developmental mechanisms that have been more extensively studied include glucocorticoid exposure, the role of the kidneys and the renin-angiotensin system. Other pathophysiological pathways have been explored, such as the role of the brain and the sympathetic nervous system, oxidative stress and epigenetic changes. As with many complex diseases, a unifying hypothesis linking the perinatal environment to elevated blood pressure and vascular dysfunction in later life cannot be presumed, and a better understanding of those mechanisms is critical before clinical trials of preventive or 'deprogramming' measures can be designed.

Evidence of infant blood pressure programming by maternal nutrition during pregnancy: a prospective randomized controlled intervention study

OBJECTIVES

To evaluate the impact of maternal nutrition during pregnancy on infant blood pressure.

STUDY DESIGN

Pregnant women (n = 256) were randomized into 3 groups: modified dietary intake according to current recommendations and probiotics (diet/probiotics), placebo (diet/placebo), and a control/placebo group. In the infants born to these women, blood pressure was recorded at age 6 months using an automated oscillometric DINAMAP R.

RESULTS

Despite significant differences in maternal dietary intakes between the study groups, the intervention focusing on maternal fat intake showed no direct impact on infants' blood pressure. Instead, a complex U-shaped interrelationship was uncovered; the highest and lowest quartiles of intakes of specific nutrients, carbohydrate (P = .006 for systolic pressure and P = .015 for diastolic pressure), and monounsaturated fatty acids (P = .029 for diastolic pressure) compared with the middle quartiles resulted in higher blood pressure at age 6 months. The pattern between maternal carbohydrate intake during pregnancy and infants' blood pressure remained significant even after adjustment for breastfeeding and body length. A reverse U-shaped trend again was observed between maternal intake of fruits and infants' systolic blood pressure (P = .077).

CONCLUSION

With a view toward programming blood pressure to adulthood, our results suggest an opportunity for dietary counseling to promote child health.

Maternal and Social Origins of Hypertension

We previously reported that in 2003 people from the Helsinki birth cohort whose blood pressures were measured, 2 different paths of growth preceded the development of hypertension. People already diagnosed with hypertension were small at birth but of average body size at age 11 years. People newly diagnosed with hypertension grew slowly in utero and through childhood. We have now examined how the mother’s body size, placental size, and living conditions after birth, 3 influences that affect growth, affect hypertension. Diagnosed hypertension was associated with low placental weight and poor living conditions after birth. The odds ratios were 1.6 (95% CI, 1.1 to 2.3) in people with placental weights <550 g, compared with those with weights >750 g, and 2.2 (95% CI, 1.5 to 3.3) in people whose fathers were laborers compared with those in upper middle-class families. Newly diagnosed hypertension was associated with a small anteroposterior diameter of the mother’s bony pelvis, a known consequence of rickets or lesser degrees of malnutrition in infancy. The odds ratio was 2.2 (95% CI, 1.4 to 3.5) in people whose mothers’ pelvic external conjugate diameters were <18 cm when compared with people whose mothers’ diameters were ≥19 cm. We conclude that one path of growth that leads to hypertension is initiated by fetal undernutrition, which may make a baby vulnerable to postnatal stress, whereas the other originates in a functional incapacity in the mother’s metabolism, possibly protein metabolism, which she acquired through undernutrition during her infancy.

Placental insufficiency results in temporal alterations in the renin angiotensin system in male hypertensive growth restricted offspring

Reduced uterine perfusion initiated in late gestation in the rat results in intrauterine growth restriction (IUGR) and development of hypertension by 4 wk of age. We hypothesize that the renin angiotensin system (RAS), a regulatory system important in the long-term control of blood pressure, may be programmed by placental insufficiency and may contribute to the etiology of IUGR hypertension. We previously reported that RAS blockade abolished hypertension in adult IUGR offspring; however, the mechanisms responsible for the early phase of hypertension are unresolved. Therefore, the purpose of this study was to examine RAS involvement in early programmed hypertension and to determine whether temporal changes in RAS expression are observed in IUGR offspring. Renal renin and angiotensinogen mRNA expression were significantly decreased at birth (80 and 60%, respectively); plasma and renal RAS did not differ in conjunction with hypertension (mean increase of 14 mmHg) in young IUGR offspring; however, hypertension (mean increase of 22 mmHg) in adult IUGR offspring was associated with marked increases in renal angiotensin-converting enzyme (ACE) activity (122%) and renal renin and angiotensinogen mRNA (7-fold and 7.4-fold, respectively), but no change in renal ANG II or angiotensin type 1 receptor. ACE inhibition (enalapril, 10 mg x kg(-1) x day(-1), administered from 2 to 4 wk of age) abolished hypertension in IUGR at 4 wk of age (decrease of 15 mmHg, respectively) with no significant depressor effect in control offspring. Therefore, temporal alterations in renal RAS are observed in IUGR offspring and may play a key role in the etiology of IUGR hypertension.

Maternal nutrition during gestation and carotid arterial compliance in the adult offspring: the Dutch famine birth cohort

OBJECTIVE

Experimental evidence indicates that maternal undernutrition during gestation may program hypertension in the offspring. We investigated whether maternal undernutrition leads to increased arterial stiffness.

METHODS

We measured carotid artery lumen diameter (LD), distensibility (DC), stiffness (beta), and compliance (CC) by M-mode ultrasound in 673 individuals, aged 56-61 years, who had been born as term singletons around the time of the 1944-45 Dutch famine.

RESULTS

Maternal famine exposure had no effect on any of the measures of carotid size or stiffness in the offspring. Low maternal weight at the end of pregnancy and low birth weight were associated with decreased LD (0.01 mm/kg maternal weight, sex-adjusted P < 0.001; 0.1 mm/kg birth weight, sex-adjusted P = 0.08) and CC (0.002 mm2/kPa per kg maternal weight, sex-adjusted P = 0.001; 0.03 mm2/kPa per kg birth weight, sex-adjusted P = 0.03), but neither was associated with increased beta, or decreased DC. These effects were not attenuated by adjusting for maternal protein/carbohydrate ratio in the third trimester. The association of low birth weight with increased CC diminished after adjusting for maternal weight. The association of maternal weight with CC was smaller when adjusted for LD.

CONCLUSION

Our findings suggest that small maternal size, not poor maternal diet, in late gestation programs decreased arterial compliance in the adult offspring by affecting vessel size rather than vessel wall stiffness.

Maternal food restriction in the second half of pregnancy affects vascular function but not blood pressure of rat female offspring

Food restriction during pregnancy in rats induces intrauterine growth retardation with consequences persisting into adulthood. In the present study we have investigated the hypothesis that malnutrition in pregnant rats may lead to altered cardiovascular function in adult female offspring. Perinatal growth retardation was induced by a 50 % reduction of normal dietary intake in rats during the second half of pregnancy. Systolic and diastolic blood pressure values and heart rate were recorded in conscious female offspring (100 d old) using a femoral artery probe. No significant differences in heart rate, or in systolic and diastolic blood pressures were recorded between control offspring and offspring of nutritionally deprived rats. In order to ascertain whether cardiovascular variables in the offspring were influenced by lactation, subgroups of offspring from food-restricted dams were fostered with lactating dams fed on a normal diet. Blood pressure and heart rate were also found to be normal in these offspring. The rise in blood pressure associated with NO inhibition was similar in all groups. Isolated resistance artery function was assessed in vitro in offspring (100–120 d old) of a second group of semi-starved dams. Small mesenteric arteries from these animals showed reduced endothelium-dependent relaxation (to acetylcholine and bradykinin), but enhanced sensitivity to exogenous NO (sodium nitroprusside). We conclude that food restriction during the second half of pregnancy and/or lactation does not induce hypertension in adult offspring, but may effect subtle changes in vascular function.

Does maternal nutrition in pregnancy and birth weight influence levels of CHD risk factors in adult life?

The fetal-origins hypothesis suggests that maternal and fetal nutrition can have a profound and sustained impact on the health of the offspring in adult life. Although there is abundant literature reporting on the associations between birth weight and disease risk factors, only a handful of studies have been able to examine the relationship between maternal nutrition in pregnancy with the health of offspring in adult life directly. Between 1942 and 1944, nearly 400 pregnant women were recruited into a dietary study to determine whether the wartime dietary rations were sufficient to prevent nutritional deficiencies. Detailed biochemical and clinical assessments were conducted for each of the women, who were followed-up until after delivery. More than 50 years later, approximately one-quarter of the adult offspring were recruited into a study to explore the possible impact of maternal nutrition in pregnancy on CHD risk factors, including glucose tolerance, blood pressure and components of the lipid profile. Results from the present study provide no evidence to support the hypothesis that birth weight or maternal nutrition in pregnancy are associated with CHD risk factors in adult life.

Developmental programming of health and disease

The environment encountered in fetal and neonatal life exerts a profound influence on physiological function and risk of disease in adult life. Epidemiological evidence suggests that impaired fetal growth followed by rapid catch-up in infancy is a strong predictor of obesity, hypertension, non-insulin-dependent diabetes and CHD. Whilst these associations have been widely accepted to be the product of nutritional factors operating in pregnancy, evidence from human populations to support this assertion is scarce. Animal studies clearly demonstrate that there is a direct association between nutrient imbalance in fetal life and later disease states, including hypertension, diabetes, obesity and renal disease. These associations are independent of changes in fetal growth rates. Experimental studies examining the impact of micro- or macronutrient restriction and excess in rodent pregnancy provide clues to the mechanisms that link fetal nutrition to permanent physiological changes that promote disease. Exposure to glucocorticoids in early life appears to be an important consequence of nutrient imbalance and may lead to alterations in gene expression that have major effects on tissue development and function. Epigenetic mechanisms, including DNA methylation, may also be important processes in early-life programming.

Down-regulation of placental transport of amino acids precedes the development of intrauterine growth restriction in rats fed a low protein diet

Intrauterine growth restriction (IUGR) represents an important risk factor for perinatal complications and for adult disease. IUGR is associated with a down-regulation of placental amino acid transporters; however, whether these changes are primary events directly contributing to IUGR or a secondary consequence is unknown. We investigated the time course of changes in placental and fetal growth, placental nutrient transport in vivo and the expression of placental nutrient transporters in pregnant rats subjected to protein malnutrition, a model for IUGR. Pregnant rats were given either a low protein (LP) diet (n = 64) or an isocaloric control diet (n = 66) throughout pregnancy. Maternal insulin, leptin and IGF-I levels decreased, whereas maternal amino acid concentrations increased moderately in response to the LP diet. Fetal and placental weights in the LP group were unaltered compared to control diet at gestational day (GD) 15, 18 and 19 but significantly reduced at GD 21. Placental system A transport activity was reduced at GD 19 and 21 in response to a low protein diet. Placental protein expression of SNAT2 was decreased at GD 21. In conclusion, placental amino acid transport is down-regulated prior to the development of IUGR, suggesting that these placental transport changes are a cause, rather than a consequence, of IUGR. Reduced maternal levels of insulin, leptin and IGF-1 may link maternal protein malnutrition to reduced fetal growth by down-regulation of key placental amino acid transporters.

DEVELOPMENTAL PROGRAMMING OF OBESITY AND TYPE 2 DIABETES

Obesity and type 2 diabetes are serious health issues in the developed world and are becoming increasingly important on a global scale. Furthermore, the marked increases in both childhood obesity and type 2 diabetes will translate to further increases in adult obesity, diabetes and associated co-morbidities in the near future; as such it has been ranked as a critical public health threat. It is a widely held view that the primary cause of obesity is the development of an obesogenic environment, due to ease of access to highly calorific food and reduced energy expenditure in work and leisure activities. In addition there is strong evidence for a genetic component to human obesity with the identification of a number of genes associated with human obesity. However, on its own the genetic component of this condition cannot account for the dramatic increase in the prevalence of obesity in recent years. Of relevance and as highlighted by epidemiological and experimental studies, is the relationship between the periconceptual, fetal and early infant phases of life and the subsequent development of adult obesity. The terms “developmental programming” and the “Developmental Origins of Adult Health and Disease” are preferentially used to describe these relationships. Despite initial controversy when these relationships were first suggested, both prospective clinical and experimental studies have clearly shown that the propensity to develop abnormalities of cardiovascular, endocrine and metabolic homeostasis in adulthood are increased when fetal development has been adversely affected. This pathogenesis is not based on genetic defects but on altered gene expression seen as a result of fetal adaptation to an adverse intrauterine environment. The relative role of genetic versus environmental factors and the mechanisms underlying developmental programming remain speculative. It is generally argued that in response to an adverse intrauterine environment, the fetus adapts its physiological development to maximise its immediate chances for survival. Owing to the plasticity of the fetus, these adaptations may include resetting of metabolic homeostasis and endocrine systems and the down-regulation of growth, commonly reflected in an altered birth phenotype. It is thought that whilst these changes in fetal physiology (i.e. the prenatal environment) may be beneficial for short term survivalin uterothey may be maladaptive in postnatal life, contributing to poor health outcomes when offspring are exposed to catch-up growth, diet-induced obesity and other factors. The “predictive adaptive response” hypothesis proposes that the degree of mismatch between the pre- and postnatal environments is a major determinant of subsequent disease. This review will address recent work in animal models and observations in the clinical and epidemiological settings onin uteroadaptations and subsequent development of obesity and type 2 diabetes.

Diet, nutrition and the prevention of type 2 diabetes

Objectives:

The overall objective of this study was to evaluate and provide evidence and recommendations on current published literature about diet and lifestyle in the prevention of type 2 diabetes.

Design:

Epidemiological and experimental studies, focusing on nutritional intervention in the prevention of type 2 diabetes are used to make disease-specific recommendations. Long-term cohort studies are given the most weight as to strength of evidence available.

Setting and subjects:

Numerous clinical trials and cohort studies in low, middle and high income countries are evaluated regarding recommendations for dietary prevention of type 2 diabetes. These include, among others, the Finnish Diabetes Prevention Study, US Diabetes Prevention Program, Da Qing Study; Pima Indian Study; Iowa Women's Health Study; and the study of the US Male Physicians.

Results:

There is convincing evidence for a decreased risk of diabetes in adults who are physically active and maintain a normal body mass index (BMI) throughout adulthood, and in overweight adults with impaired glucose tolerance who lose weight voluntarily. An increased risk for developing type 2 diabetes is associated with overweight and obesity; abdominal obesity; physical inactivity; and maternal diabetes. It is probable that a high intake of saturated fats and intrauterine growth retardation also contribute to an increased risk, while non-starch polysaccharides are likely to be associated with a decreased risk. From existing evidence it is also possible that omega-3 fatty acids, low glycaemic index foods and exclusive breastfeeding may play a protective role, and that total fat intake andtransfatty acids may contribute to the risk. However, insufficient evidence is currently available to provide convincing proof.

Conclusions:

Based on the strength of available evidence regarding diet and lifestyle in the prevention of type 2 diabetes, it is recommended that a normal weight status in the lower BMI range (BMI 21–23) and regular physical activity be maintained throughout adulthood; abdominal obesity be prevented; and saturated fat intake be less than 7% of the total energy intake.

Maternal diabetes mellitus--early consequences for the offspring

Although several studies have focused on the effects of nutritional status during intrauterine development, few have addressed the impact of maternal diabetes mellitus on renal function and morphology in the young offspring. In the present study, renal morpho-functional aspects were studied in the offspring of diabetic rats. Diabetes was induced in female rats with a single dose of streptozotocyn (STZ), 10 days before mating. After weaning, the offspring (DO) had free access to food and water. Arterial blood pressure was measured, by tail plethysmography, from 2 months on. Renal function was evaluated in 2- and 3-month-old rats in the DO group and in controls (C). Analysis of renal morphology was carried out in newborn and in 1-, 2- and 3-month-old rats in both groups. Although the nephron number was not changed in the DO group, glomerular hypertrophy was observed from 2 months on. At the same age, the glomerular filtration rate was significantly reduced in DO, and blood pressure was significantly increased, when compared to C. Glucose tolerance test (GTT) from DO showed a different profile when compared to C. The number of PCNA positive cells in renal tissue was similar in both groups. Our data suggests that exposure to intrauterine diabetes may be an important cause of both impaired renal function and hypertension in offspring, without changes in the nephron number.

Data collected on maternal dietary exposures in the Danish National Birth Cohort

Recent research suggests that the diet consumed in, or shortly before, pregnancy can potentially lead to maldevelopment and diseases in the offspring, which may become apparent at any time from the embryonic stage until old age. For example, maternal diet may affect the chance of twinning (and associated complications), malformation risk, brain development, and the offspring's fecundity and risk of contracting cardiovascular diseases and cancer in adult life. Prospectively designed longitudinal studies with sufficient size and data quality are much needed to substantiate or refute these hypotheses. At present, the Danish National Birth Cohort is likely to be the largest epidemiological database containing extensive information on maternal dietary exposures. By October 2002, 100 000 women had been recruited in early pregnancy, for long-term follow-up of themselves and their offspring. The present paper details the information available in the database on early nutritional exposures with emphasis on maternal dietary intake. We also present distributions of selected nutritional exposures.

Higher maternal dietary protein intake in late pregnancy is associated with a lower infant ponderal index at birth

AIM

A high ponderal index at birth has been associated with later obesity and it has been suggested that intervention to prevent obesity and its sequela should consider the antenatal period. In this context, we investigated the association between maternal nutrition and birth anthropometry.

DESIGN

We analyzed data on 1040 mother-infant pairs collected during the Tasmanian Infant Health Survey (TIHS), Tasmania, 1988-1989. Maternal dietary intake during pregnancy was measured by food frequency questionnaire (FFQ) applied soon after birth. Outcomes of interest were birth weight, birth length, head circumference, ponderal index, head circumference -to-ponderal index ratio, placenta-to-birth weight ratio and head circumference-to-birth length index.

RESULTS

In multiple regression model, an increase of 10 g of absolute protein intake/day was associated with a reduction in birth weight of 17.8 g (95% CI: -32.7, -3.0; P=0.02). Protein intake was also associated negatively with ponderal index (beta=-0.01; 95% CI: -0.02, -0.00; P=0.01). A 1 % increase in carbohydrate intake resulted in a 1% decline in placental weight relative to birth weight. Higher protein intake in the third trimester was associated with a reduced ponderal index among large birth weight infants but not low birth weight infants.

CONCLUSIONS

This raises the possibility that any effect of high protein in altering infant anthropometry at birth may involve changes in body composition and future work to examine how a high-protein diet influences body composition at birth is warranted.

Geographical variation in neonatal phenotype

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Geographical variation in relationships between parental body size and offspring phenotype at birth

BACKGROUND

Size and body proportions at birth are partly determined by maternal body composition, but most studies of mother-baby relationships have only considered the effects of maternal height and weight on offspring birth weight, and few have examined the size of effects. Paternal size and body composition also play a role, primarily through the fetal genome, although few studies have investigated relationships with neonatal phenotype.

METHODS

Data from the UK, Finland, India, Sri Lanka, China, DR Congo, Nigeria and Jamaica were used to investigate the effects of maternal measures (derived at 30 weeks' gestation, n=16,418), and also paternal size (n=3,733) on neonatal phenotype, for singleton, live-born, term births.

RESULTS

After accounting for variation in maternal size and shape across populations, differences in neonatal phenotype were markedly reduced. Mother-baby relationships were similar across populations, although some were stronger in developing countries. Maternal height was generally the strongest predictor of neonatal length, maternal head circumference of neonatal head and maternal skinfold thickness of neonatal skinfolds. Relationships with maternal arm muscle area were generally weak. Effects of paternal height and body mass index were weaker than the equivalent maternal measurements in most studies.

CONCLUSIONS

Differences in maternal body composition account for a large part of the geographical variation in neonatal phenotype. The size of the effects of all maternal measures on neonatal phenotype suggests that nutrition at every stage of the mother's life cycle may influence fetal growth. Further research is needed into father-baby relationships and the genetic mechanisms that influence fetal growth.

High-protein nutrition during pregnancy and lactation programs blood pressure, food efficiency, and body weight of the offspring in a sex-dependent manner

Maternal low-protein diet during pregnancy is a risk factor for cardiovascular disease of the offspring in later life. The impact of high-protein diet during pregnancy on the cardiovascular phenotype of the offspring, however, is still unknown. We examined the influence of a high-protein diet during pregnancy and lactation on the renal, hemodynamic, and metabolic phenotype of the F1 generation. Female Wistar rats were either fed a normal protein diet (20% protein: NP) or an isocaloric high-protein diet (40% protein: HP) throughout pregnancy and lactation. At weaning, the offspring were fed with standard diet, and they were allocated according to sex and maternal diet to four groups: normal-protein male (NPm, n = 25), normal-protein female (NPf, n = 19), high-protein male (HPm, n = 24), high-protein female (HPf, n = 29). During the experiment (22 wk), the animals were characterized by repeated measurement of body weight, food intake, blood pressure, glucose tolerance, energy expenditure, and kidney function. At the end of the study period histomorphological analyses of the kidneys and weight measurement of reproductive fat pads were conducted. There were no differences in birth weight between the study groups. No influence of maternal diet on energy expenditure, glucose tolerance, and plasma lipid levels was detected. Blood pressure and glomerulosclerosis were elevated in male offspring only, whereas female offspring were characterized by an increased food efficiency, higher body weight, and increased fat pads. Our study demonstrates that a high-protein diet during pregnancy and lactation in rats programs blood pressure, food efficiency, and body weight of the offspring in a sex-dependent manner.

Wheezing and eczema in relation to infant anthropometry: evidence of developmental programming of disease in childhood

Early life factors and, in particular, the fetal environment have been suggested to programme risk of allergic disease in later life. Diversion of nutrients away from immune organs towards the brain, a process termed brain sparing, has been proposed as a mechanism underpinning this association. The study population was a group of 256 seven-year old children from the UK recruited from two general practitioner surgeries. Historical anthropometric data from birth to age three and current anthropometry were assessed as predictors of parent-reported wheeze and eczema. Eczema at seven years was not related to any anthropometric indices at birth or during infancy. A smaller head circumference at 10-15 days of age was noted in children with current wheeze at age 7 years (P = 0.018) and this relationship persisted after adjustment for current anthropometry and confounders. Comparison of children with head circumference over 36.5 cm at 10-15 days with those with head circumference under 35.5 cm, showed reduced odds for wheeze at 7 years (OR 0.12, 95% CI 0.03-0.44, P(trend) = 0.009). These data suggest that factors that determine fetal growth may be associated with wheeze in childhood and support the developmental origins of health and disease hypothesis. Brain sparing does not appear to play a role in this early life programming.

Diet around conception and during pregnancy--effects on fetal and neonatal outcomes

Substrate supply to the fetus is a major regulator of prenatal growth. Maternal nutrition influences the availability of nutrients for transfer to the fetus. Animal experiments demonstrate that restriction of maternal protein or energy intake can retard fetal growth. Effects of maternal nutrition vary with the type and timing of the restriction and the species studied. Maternal undernutrition before conception and/or in early pregnancy can alter fetal physiology in late gestation, and influence postnatal function, often without measurable effects on birth size. In contrast, to date, observational and intervention studies in humans provide limited support for a major role of maternal nutrition in determining birth size, except where women are quite malnourished. However, recent studies report associations between newborn size and the balance of macronutrients in women's diets in Western settings. Associations between maternal dietary composition and adult blood pressure of the offspring are also reported in human populations. Most studies in women have focused on dietary content or supplementation during mid-late pregnancy. Further investigation of how maternal dietary composition, before conception and throughout pregnancy, affects fetal physiology and health of the baby will increase the understanding of how maternal diet and nutritional status influence fetal, neonatal and longer-term outcomes.

What is the effect of adjusting for more than one measure of current body size on the relation between birthweight and blood pressure?

The statistical validity of the negative associations observed between birthweight and disease in later life has recently been questioned, because these associations might be due, in part, to inappropriate adjustment for current body size, creating a statistical artefact known as the 'reversal paradox'. The aim of this study was to explore the effect of adjusting for more than one measure of current body size on the association between birthweight and disease in later life using simulations and meta-analyses of empirical studies. The simulations examined the relation between birthweight and adult systolic blood pressure before and after adjusting for one, two or three measures of current body size by including current weight and subsequently adding body mass index and height in successive analytical models. Meta-analyses were then performed to compare the effect sizes observed among empirical studies reporting associations between birthweight and blood pressure before and after adjusting for one or two measures of current body size. The meta-analyses confirmed the results of the simulations - both showed that associations between birthweight and blood pressure tend to become increasingly negative following adjustment for current body size, and that this effect is enhanced after adjusting for additional measures of current body size.

Hazards associated with pregnancies and deliveries in lysinuric protein intolerance

Lysinuric protein intolerance (LPI) is an autosomal recessive transport disorder of the dibasic amino acids. The defect leads to deficiency of lysine, arginine, and ornithine and, secondarily, to a functional disorder of the urea cycle. Transient postprandial hyperammonemia and subsequent persistent protein aversion, linked with several other biochemical and clinical characteristics of the disease, suggest an increased risk for maternal and fetal complications during pregnancy and delivery. Our unique material on the outcomes of 18 pregnancies of 9 Finnish mothers with LPI and the follow-up of their 19 children shows that maternal LPI is truly associated with increased risk of anemia, toxemia, and intrauterine growth retardation during pregnancy and bleeding complications during delivery. Successful pregnancies and deliveries can still be achieved with careful follow-up of blood pressure and laboratory values. The children of the mothers with LPI generally develop normally. Special care of maternal protein nutrition and control of ammonemia, anemia, and toxemia during pregnancy are essential. We propose centralization of deliveries to obstetric units with capability to deal with bleeding complications and rare inborn errors of metabolism.

Hypotheses on the Fetal Origins of Adult Diseases: Contributions of Epidemiological Studies

Epidemiological studies have demonstrated associations between low birth weight and cardiovascular disease, type 2 diabetes and their risk factors in adult life. These findings have led to sharp debates in the literature concerning potential methodological study flaws and the effect size and causality of the associations. More recent studies seem to have overcome most methodological flaws and suggest a small effect size of low birth weight on adult diseases for the individual. However, the effect size may still be important on a population level. Various causal pathways have been hypothesized as mechanisms underlying these associations. These hypotheses have proposed central roles for (1) fetal undernutrition, (2) increased cortisol exposure, (3) genetic susceptibility and (4) accelerated post-natal growth. These hypotheses have been studied in various epidemiological study designs. Thus far, it is still not known which mechanisms underlie the associations between low birth weight and diseases in adult life. The causal pathways linking low birth weight to diseases in later life seem to be complex and may include combined environmental and genetic mechanisms in various periods of life. Well-designed epidemiological studies are necessary to estimate the population effect size and to identify the underlying mechanisms. This knowledge is needed to develop strategies for identifying groups at risk and prevention focused on early life.

Long-term effects of maternal diabetes on vascular reactivity and renal function in rat male offspring

Fetal growth impairment can occur in pregnancy complicated by diabetes. Although several studies have focused the effects of nutritional status on intrauterine development, the long-term impact of maternal diabetes on vascular and renal function in the offspring is poorly investigated. In the present study, blood pressure profiles and renal function parameters were investigated in the offspring of diabetic rats (DO). Female rats were made diabetic throughout gestation with a single dose of streptozotocyn (STZ) 10 d before mating. After weaning, the offspring had free access to food and water. Arterial pressure was evaluated every 15 d. Functional and morphometric kidney studies were performed in newborn, 3, 6 and 12-mo-old male rats in DO and in controls, C. Although maternal diabetes did not affect nephron number in the young adult rat, glomerular hypertrophy developed from 3 mo on. Glomerular Filtration Rate and Renal Plasma Flow were observed to be significantly decreased in DO when compared with C, from 3 mo on. In DO, hypertension was observed from 8 wk on and persisted elevated throughout the experimental period (12 mo). Vascular reactivity, evaluated in mesenteric arterial bed showed a decreased endothelium-dependent vasodilatation in 12-mo-old DO animals, while preserved response to sodium nitroprusside was demonstrated. Our data show that exposure to intrauterine diabetes induced by STZ does not affect nephron number in the young offspring but can cause permanent changes in Nitric Oxide (NO)-related vascular response, which, in turn may accelerate the natural age-related nephron loss.

Low birth weight, nephron number, and kidney disease

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

Blood pressure among very low birth weight (<1.5 kg) young adults

Our objective was to compare the blood pressure of 20-y-old very low birth weight (VLBW; <1.5 kg) individuals with that of normal birth weight (NBW) control individuals. The population included 195 VLBW (92 female and 103 male) and 208 NBW (107 female and 101 male) individuals who were born between 1977 and 1979. Independent effects of birth weight status (VLBW versus NBW) and within the VLBW cohort of intrauterine growth (birth weight z score) were examined via multiple regression analyses. VLBW individuals had a higher mean systolic blood pressure (SBP) than NBW control individuals (114 +/- 11 versus 112 +/- 13 mm Hg). SBP for VLBW female infants was 110 +/- 9 versus NBW 107 +/- 12 and for VLBW male individuals was 118 +/- 11 versus NBW 117 +/- 11 mm Hg. After adjustment for gender, race, and maternal education, the difference in SBP between VLBW and NBW individuals was 1.9 mm Hg but was 3.5 mm after also adjustment for later size (20-y weight and height z scores), which reflects catch-up growth. For female individuals, the difference in SBP between VLBW and NBW individuals was significant both unadjusted and adjusted for later size, whereas for male individuals, the difference was significant only after adjustment for later size. Intrauterine growth did not have a significant effect on SBP within the VLBW group, even after adjustment for later size. VLBW individuals, specifically female individuals, have a higher SBP than NBW control individuals. This is not explained by intrauterine growth failure.

Developmental determinants of blood pressure in adults

Over the past 20 years a large and varied body of research has attempted to make the case for the developmental origins of elevated adult blood pressure (BP). Experimental animal research has identified plausible biological mechanisms through which fetal nutritional insufficiency may affect adult BP. The majority of human epidemiologic studies demonstrate an inverse association of birth weight (the most commonly used marker of fetal nutrition) with adult BP and higher risk of hypertension among individuals with lower weight at birth. The most adverse BP outcomes occur among individuals who were small at birth but relatively large as adults, a finding that suggests a role for postnatal growth. We critically review the literature on proposed mechanisms and epidemiologic evidence for developmental origins of adult BP and hypertension, considering associations with birth weight, maternal nutrition during pregnancy, child growth patterns, and infant feeding.