Is blood pressure increased 19 years after intrauterine growth restriction and preterm birth? A prospective follow-up study in The Netherlands

Association of intrauterine growth restriction and low birth weight with acute kidney injury in preterm neonates

BACKGROUND

Preterm birth alters nephrogenesis and reduces the total nephron number. Intrauterine growth restriction (IUGR) seems to worsen nephron loss, but only a few studies have investigated its role in neonatal kidney impairment. We investigated whether IUGR, defined as reduced estimated fetal growth and/or placental flow alterations and low birth weight z-score, increases the risk of developing acute kidney injury (AKI) in very preterm infants.

METHODS

We performed a retrospective study including infants born with a birth weight (BW) ≤ 1500 g and/or gestational age (GA) ≤ 32 weeks admitted to our center between January 2016 and December 2021. Neonatal AKI was defined according to the neonatal KDIGO classification based on the decline of urine output and/or creatinine elevation. We used multivariable linear regressions to verify the association between AKI and GA, BW z-score, IUGR definition, and hemodynamically significant patent ductus arteriosus (PDA).

RESULTS

We included 282 infants in the analysis, with a median (IQR) GA = 29.4 (27.4, 31.3) weeks, BW = 1150 (870, 1360) g, and BW z-score =  - 0.57 (- 1.64, 0.25). AKI was diagnosed in 36 (13%) patients, and 58 (21%) had PDA. AKI was significantly associated with BW z-score (beta (std. error) =  - 0.08 (0.03), p = 0.008) and severe IUGR (beta (std. error) = 0.21 (0.08), p = 0.009), after adjusting for GA and PDA.

CONCLUSIONS

Our data suggest that low BW z-score and IUGR could represent adjunctive risk factors for kidney impairment in preterm babies. A higher resolution version of the Graphical abstract is available as Supplementary information.

Perinatal intermittent hypoxia increases early susceptibility to ANG II-induced hypertension in adult male but not in female Sprague-Dawley rats

Prenatal, perinatal, and adulthood exposure to chronic intermittent hypoxia (IH) increases blood pressure in rodents. Males exposed to chronic IH have higher blood pressure versus females. However, it is unknown if this same-sex difference exists with acute perinatal IH. We tested the hypothesis that acute perinatal IH increases baseline blood pressure and enhances sensitivity to angiotensin II (ANG II)-induced hypertension in male Sprague-Dawley rats. Male and female pups were randomized to control (room air) or IH (10 min of ∼10% O2 for 3 times/day) for the first 8 days of life. IH decreased oxygen saturation, as confirmed via a pulse oximeter. Pups were weaned at postnatal day 21. Blood pressure was measured via telemetry beginning at 14 wk of age and analyzed separately into light and dark phases to assess circadian rhythm. Osmotic minipumps to deliver ANG II were implanted at 15 wk of age. Perinatal IH exposure did not alter baseline blood pressure. One week of ANG II treatment increased blood pressure in light and dark periods in males exposed to IH versus control; there was no effect in females. Blood pressure among the groups was comparable following 2 wk of ANG II infusion. Perinatal IH did not change the circadian rhythm. Following ANG II treatment, indexes of renal injury were measured. Perinatal IH did not alter kidney size, structure, nephron number, or creatinine clearance. These data indicate that acute perinatal IH enhances early ANG II-induced hypertension in males, independent of nephron loss or decreases in body weight or kidney function.NEW & NOTEWORTHY The impact of acute intermittent hypoxia (IH) in early life on blood pressure in adulthood is unknown. This study used a new model exposing female and male rat pups to acute IH in the first 8 days of life, without exposing the dam. Although baseline blood pressure was not altered in adulthood, IH increased susceptibility to angiotensin II hypertension only in males, supporting increased susceptibility of males exposed to IH to a second cardiovascular stressor.

Novel Insights on Dietary Polyphenols for Prevention in Early-Life Origins of Hypertension: A Review Focusing on Preclinical Animal Models

Polyphenols are the largest group of phytochemicals with health benefits. Early life appears to offer a critical window of opportunity for launching interventions focused on preventing hypertension, as increasing evidence supports the supposition that hypertension can originate in early life. Although polyphenols have antihypertensive actions, knowledge of the potential beneficial action of the early use of polyphenols to avert the development of hypertension is limited. Thus, in this review, we first provide a brief summary of the chemistry and biological function of polyphenols. Then, we present the current epidemiological and experimental evidence supporting the early-life origins of hypertension. We also document animal data on the use of specific polyphenols as an early-life intervention to protect offspring against hypertension in adulthood and discuss underlying mechanisms. Continued research into the use of polyphenols to prevent hypertension from starting early in life will have far-reaching implications for future health.

Oxidative Stress-Induced Hypertension of Developmental Origins: Preventive Aspects of Antioxidant Therapy

Hypertension remains the leading cause of disease burden worldwide. Hypertension can originate in the early stages of life. A growing body of evidence suggests that oxidative stress, which is characterized as a reactive oxygen species (ROS)/nitric oxide (NO) disequilibrium, has a pivotal role in the hypertension of developmental origins. Results from animal studies support the idea that early-life oxidative stress causes developmental programming in prime blood pressure (BP)-controlled organs such as the brain, kidneys, heart, and blood vessels, leading to hypertension in adult offspring. Conversely, perinatal use of antioxidants can counteract oxidative stress and therefore lower BP. This review discusses the interaction between oxidative stress and developmental programming in hypertension. It will also discuss evidence from animal models, how oxidative stress connects with other core mechanisms, and the potential of antioxidant therapy as a novel preventive strategy to prevent the hypertension of developmental origins.

Cardiovascular Diseases of Developmental Origins: Preventive Aspects of Gut Microbiota-Targeted Therapy

Cardiovascular diseases (CVDs) can originate from early life. Accumulating evidence suggests that gut microbiota in early life is linked to CVDs in later life. Gut microbiota-targeted therapy has gained significant importance in recent decades for its health-promoting role in the prevention (rather than just treatment) of CVDs. Thus far, available gut microbiota-based treatment modalities used as reprogramming interventions include probiotics, prebiotics, and postbiotics. The purpose of this review is, first, to highlight current studies that link dysbiotic gut microbiota to the developmental origins of CVD. This is followed by a summary of the connections between the gut microbiota and CVD behind cardiovascular programming, such as short chain fatty acids (SCFAs) and their receptors, trimethylamine-N-oxide (TMAO), uremic toxins, and aryl hydrocarbon receptor (AhR), and the renin-angiotensin system (RAS). This review also presents an overview of how gut microbiota-targeted reprogramming interventions can prevent the developmental origins of CVD from animal studies. Overall, this review reveals that recent advances in gut microbiota-targeted therapy might provide the answers to reduce the global burden of CVDs. Still, additional studies will be needed to put research findings into practice.

Preventive Aspects of Early Resveratrol Supplementation in Cardiovascular and Kidney Disease of Developmental Origins

The increase in the incidence of cardiovascular diseases (CVDs) and kidney disease has stimulated research for strategies that could prevent, rather than just treat, both interconnected disorders. Resveratrol, a polyphenolic compound with pleiotropic biofunctions, has shown health benefits. Emerging epidemiological data supports that early life environmental insults are regarded as increased risks of developing CVDs and kidney disease in adulthood. Conversely, both disorders could be reversed or postponed by shifting interventions from adulthood to earlier stage by so-called reprogramming. The purpose of this review is first to highlight current epidemiological studies linking cardiovascular and renal programming to resulting CVD and kidney disease of developmental origins. This will be followed by a summary of how resveratrol could exert a positive influence on CVDs and kidney disease. This review also presents an overview of the evidence documenting resveratrol as a reprogramming agent to protect against CVD and kidney disease of developmental origins from animal studies and to outline the advances in understanding the underlying molecular mechanisms. Overall, this review reveals the need for future research to further clarify the reprogramming effects of resveratrol before clinical translation.

Identification of Latent Risk Clinical Attributes for Children Born Under IUGR Condition Using Machine Learning Techniques

BACKGROUND AND OBJECTIVE

Intrauterine Growth Restriction (IUGR) is a condition in which a fetus does not grow to the expected weight during pregnancy. There are several well documented causes in the literature for this issue, such as maternal disorder, and genetic influences. Nevertheless, besides the risk during pregnancy and labour periods, in a long term perspective, the impact of IUGR condition during the child development is an area of research itself. The main objective of this work is to propose a machine learning solution to identify the most significant features of importance based on physiological, clinical or socioeconomic factors correlated with previous IUGR condition after 10 years of birth.

METHODS

In this work, 41 IUGR (18 male) and 34 Non-IUGR (22 male) children were followed up 9 years after the birth, in average (9.1786 ± 0.6784 years old). A group of machine learning algorithms is proposed to classify children previously identified as born under IUGR condition based on 24-hours monitoring of ECG (Holter) and blood pressure (ABPM), and other clinical and socioeconomic attributes. In additional, an algorithm of relevance determination based on the classifier is also proposed, to determine the level of importance of the considered features.

RESULTS

The proposed classification solution achieved accuracy up to 94.73%, and better performance than seven state-of-the-art machine learning algorithms. Also, relevant latent factors related to HRV and BP monitoring are proposed, such as: day-time heart rate (day-time HR), day-night systolic blood pressure (day-night SBP), 24-hour standard deviation (SD) of SBP, dropped, morning cortisol creatinine, 24-hour mean of SDs of all NN intervals for each 5 minutes segment (24-hour SDNNi), among others.

CONCLUSION

With outstanding accuracy of our proposed solutions, the classification system and the indication of relevant attributes may support medical teams on the clinical monitoring of IUGR children during their childhood development.

Size at birth, growth trajectory in early life, and cardiovascular and metabolic risks in early adulthood: EPICure study

OBJECTIVE

To investigate whether size at birth and growth trajectories in infancy and childhood are associated with determinants of cardiovascular and metabolic risks in young adults born extremely preterm (EP, <26 weeks of gestation).

METHODS

We used longitudinal data from the EPICure study of 129 EP survivors up to 19 years in the UK and Ireland in 1995. Determinants of cardiovascular and metabolic risks at 19 years included the presence of metabolic syndrome, body mass index (BMI) and systolic blood pressure (SBP). Predictors were birth weight for gestation and gain in weight z-scores in the following periods: birth-postmenstrual age of 40 weeks (term), infancy (term-2.5 years), early childhood (2.5-6.0 years) and late childhood (6-11 years).

RESULTS

Metabolic syndrome was present in 8.7% of EP participants at 19 years. Compared with subjects without metabolic syndrome, those with metabolic syndrome tended to have a smaller size at birth (difference in means: -0.55 SD, 95% CI -1.10 to 0.01, p=0.053) and a greater increase in weight z-scores from term to 2.5 years (difference in means: 1.00 SD, 95% CI -0.17 to 2.17, p=0.094). BMI at 19 years was positively related to growth from 2.5 to 6.0 years ( β : 1.03, 95% CI 0.31 to 1.75, p=0.006); an inverse association with birthweight z-scores was found in the lower socioeconomic status group ( β : -1.79, 95% CI -3.41 to -0.17, p=0.031). Central SBP was positively related to growth from 2.5 to 6.0 years ( β : 1.75, 95% CI 0.48 to 3.02, p=0.007).

CONCLUSION

Size at EP birth and increased catch-up in weight from 2.5 to 6.0 years were associated with BMI and central SBP in early adulthood.

Preventing Developmental Origins of Cardiovascular Disease: Hydrogen Sulfide as a Potential Target?

The cardiovascular system can be programmed by a diversity of early-life insults, leading to cardiovascular disease (CVD) in adulthood. This notion is now termed developmental origins of health and disease (DOHaD). Emerging evidence indicates hydrogen sulfide (H₂S), a crucial regulator of cardiovascular homeostasis, plays a pathogenetic role in CVD of developmental origins. Conversely, early H₂S-based interventions have proved beneficial in preventing adult-onset CVD in animal studies via reversing programming processes by so-called reprogramming. The focus of this review will first summarize the current knowledge on H₂S implicated in cardiovascular programming. This will be followed by supporting evidence for the links between H₂S signaling and underlying mechanisms of cardiovascular programming, such as oxidative stress, nitric oxide deficiency, dysregulated nutrient-sensing signals, activation of the renin–angiotensin system, and gut microbiota dysbiosis. It will also provide an overview from animal models regarding how H₂S-based reprogramming interventions, such as precursors of H₂S and H₂S donors, may prevent CVD of developmental origins. A better understanding of cardiovascular programming and recent advances in H₂S-based interventions might provide the answers to bring down the global burden of CVD.

Effect of Correcting the Postnatal Age of Preterm-Born Children on Measures of Associations Between Infant Length-for-Age z Scores and Mid-Childhood Outcomes

Child growth standards are commonly used to derive age- and sex-standardized anthropometric indices but are often inappropriately applied to preterm-born children (<37 weeks of gestational age (GA)) in epidemiology studies. Using the 2004 Pelotas Birth Cohort, we examined the impact of correcting for GA in the application of child growth standards on the magnitude and direction of associations in 2 a priori–selected exposure-outcome scenarios: infant length-for-age z score (LAZ) and mid-childhood body mass index (scenario A), and infant LAZ and mid-childhood intelligence quotient (scenario B). GA was a confounder that had a strong (scenario A) or weak (scenario B) association with the outcome. Compared with uncorrected postnatal age, using GA-corrected postnatal age attenuated the magnitude of associations, particularly in early infancy, and changed inferences for associations at birth. Although differences in the magnitude of associations were small when GA was weakly associated with the outcome, model fit was meaningfully improved using corrected postnatal age. When estimating population-averaged associations with early childhood growth in studies where preterm- and term-born children are included, incorporating heterogeneity in GA at birth in the age scale used to standardize anthropometric indices postnatally provides a useful strategy to reduce standardization errors.

Reproductive risks in 35-year-old adults born very preterm and/or with very low birth weight: an observational study

Evidence suggests that increased survival over the last decades of very preterm (VPT; gestational age < 32 weeks)- and very low birth weight (VLBW; birth weight < 1500 g)-born infants is not matched by improved outcomes. The objective of our study was to evaluate the reproductive rate, fertility, and pregnancy complications in 35-year-old VPT/VLBW subjects. All Dutch VPT/VLBW infants born alive in 1983 and surviving until age 35 (n = 955) were eligible for a POPS-35 study. A total of 370 (39%) subjects completed a survey on reproductive rate, fertility problems, pregnancy complications, and perinatal outcomes of their offspring. We tested differences in these parameters between the VPT/VLBW subjects and their peers from Dutch national registries. POPS-35 participants had less children than their peers in the CBS registry. They reported more problems in conception and pregnancy complications, including a three times increased risk of hypertension during pregnancy.Conclusion: Reproduction is more problematic in 35-year olds born VPT/VLBW than in the general population, possibly mediated by an increased risk for hypertension, but their offspring have no elevated risk for preterm birth. What is known: At age 28, the Dutch national POPS cohort, born very preterm or with a very low birth in 1983, had lower reproductive rates than the general Dutch population (female 23% versus 32% and male 7% versus 22%). What is new: At age 35, the Dutch POPS cohort still had fewer children than the general Dutch population (female 56% versus 74% and male 40% versus 56%). Females in the POPS cohort had a higher risk of fertility problems and pregnancy complications than their peers in the Dutch national registries, but their offspring had no elevated risk for preterm birth.

Prematurity, perinatal inflammatory stress, and the predisposition to develop chronic kidney disease beyond oligonephropathy

Prematurity and perinatal stress, such as intrauterine growth restriction (IUGR) and chorioamnionitis, are pathological processes creating an impaired intrauterine environment. These intrauterine factors are associated with the development of proteinuria, hypertension, and chronic kidney disease (CKD) later in life. Initially, this was thought to be secondary to oligonephropathy, subsequent glomerular hypertrophy, and hyperfiltration, leading to glomerulosclerosis, a further decrease in nephron number, and finally CKD. Nowadays, there is increasing evidence that prematurity and perinatal stress affect not only nephron endowment but also the maturation of podocytes and vasculogenesis. IUGR is associated with podocyte damage and an aggravated course of nephrotic syndrome. Moreover, preterm birth and IUGR are known to cause upregulation of the postnatal renin-angiotensin system, resulting in hypertension. Chorioamnionitis causes damage to the glomeruli, thereby predisposing to the development of glomerulosclerosis. This review aims to summarize current knowledge on the influence of prematurity, IUGR, and chorioamnionitis on the development of different glomerular structures. After summarizing human and experimental data on low nephron number in general, a specific focus on the current understanding of podocyte and glomerular capillary formation in relation to prematurity and different causes of perinatal stress is presented.

Effects of maternal protein restriction on central and peripheral renin-angiotensin systems in male rat offspring

AIMS

We investigated the involvement of the renin angiotensin system (RAS) on the cardiorespiratory control in rats from dams fed with a low-protein diet.

MAIN METHODS

Male offspring were obtained from dams fed a normoprotein diet (NP, 17% casein) and low-protein diet (LP, 8% casein) during pregnancy and lactation. Direct measurements of arterial pressure (AP), heart rate (HR) and respiratory frequency (RF) were recorded in awake 90-day-old at resting and after losartan potassium through either intracerebroventricular (ICV) microinjections or intravenous (IV) administration. Cardiovascular variability was evaluated by spectral analysis. Peripheral chemoreflex sensitivity was assessed through the potassium cyanide (KCN; 40 μg/0.1 ml/rat, IV). Gene expression was evaluated by qPCR, and MAPK (Mitogen Activated Protein Kinase) expression was evaluated by western blot.

KEY FINDINGS

The LP offspring had higher mean AP (MAP) and RF than NP offspring. In the spectral analysis, the LP rats also showed higher low frequency of systolic AP (NP: 2.7 ± 0.3 vs. LP: 5.0 ± 1.0 mmHg). After ICV losartan, MAP and RF in LP rats remained higher than those in NP rats, but without changes in HR. The peripheral chemoreflex was similar between the groups. LP group had lower gene expression of Rac1 (Ras-related C3 botulinum toxin substrate 1) (NP: 1.13 ± 0.06 vs. LP: 0.88 ± 0.08). Peripherally, LP rats had larger delta of MAP after IV losartan (NP: -9.8 ± 2 vs. LP: -23 ± 6 mmHg), without changes in HR and RF.

SIGNIFICANCE

In rats, the RAS participates peripherally, but not centrally, in the maintenance of arterial hypertension in male offspring induced by maternal protein restriction.

Albuminuria, Hypertension, and Reduced Kidney Volumes in Adolescents Born Extremely Premature

Background: Premature birth is associated with decreased nephron number and an increased risk for chronic kidney disease (CKD). To inform the development of guidelines for kidney follow up of children born prematurely, we undertook a study of individuals born extremely preterm, with the aim of characterizing the prevalence and predictors of microalbuminuria, elevated blood pressure, and/or abnormal kidney volume in adolescence. Methods: Study participants (n = 42) were born before 28 weeks of gestation and were enrolled at birth in the Extremely Low Gestational Age Newborns (ELGAN) study. When participants were 15 years old, we obtained 2 manual blood pressures, a spot urine microalbumin measurement, and sonographic measurements of kidney length and volume. Results: Of the 42 participants, 60% were male, 52% were Caucasian (18% Hispanic), and 43% were African-American. Their median age was 15 (IQR 15, 15.3) years. In 33.3% of the cohort, blood pressure was elevated (>120/80 mmHg). Microalbuminuria (>30 mg/g) was present in 11.9% of the cohort, and kidney volume below the 10th percentile of normative data was present in 14%. Twenty-one (50%) of the sample had at least one kidney abnormality (microalbuminuria, elevated blood pressures, and/or kidney hypoplasia); these individuals were more likely to have experienced neonatal hypotension [55% vs. 17% among those with no kidney abnormality, p = 0.02]. Conclusions: Half of adolescents in this subset of ELGAN cohort have at least one risk factor of kidney disease (reduced kidney volume, microalbuminuria, and/or elevated blood pressures) at 15 years of age. This study suggests the importance of monitoring kidney outcomes in children after extremely preterm birth, especially those with a history of neonatal hypotension.

Risk of hypertension following perinatal adversity: IUGR and prematurity

Consistent with the paradigm shifting observations of David Barker and colleagues that revealed a powerful relationship between decreased weight through 2 years of age and adult disease, intrauterine growth restriction (IUGR) and preterm birth are independent risk factors for the development of subsequent hypertension. Animal models have been indispensable in defining the mechanisms responsible for these associations and the potential targets for therapeutic intervention. Among the modifiable risk factors, micronutrient deficiency, physical immobility, exaggerated stress hormone exposure and deficient trophic hormone production are leading candidates for targeted therapies. With the strong inverse relationship seen between gestational age at delivery and the risk of hypertension in adulthood trumping all other major cardiovascular risk factors, improvements in neonatal care are required. Unfortunately, therapeutic breakthroughs have not kept pace with rapidly improving perinatal survival, and groundbreaking bench-to-bedside studies are urgently needed to mitigate and ultimately prevent the tsunami of prematurity-related adult cardiovascular disease that may be on the horizon. This review highlights our current understanding of the developmental origins of hypertension and draws attention to the importance of increasing the availability of lactation consultants, nutritionists, pharmacists and physical therapists as critical allies in the battle that IUGR or premature infants are waging not just for survival but also for their future cardiometabolic health.

Postnatal nutritional intakes and hyperglycemia as determinants of blood pressure at 6.5 years of age in children born extremely preterm

BACKGROUND

Adverse developmental programming by early-life exposures might account for higher blood pressure (BP) in children born extremely preterm. We assessed associations between nutrition, growth and hyperglycemia early in infancy, and BP at 6.5 years of age in children born extremely preterm.

METHODS

Data regarding perinatal exposures including nutrition, growth and glycemia status were collected from the Extremely Preterm Infants in Sweden Study (EXPRESS), a population-based cohort including infants born <27 gestational weeks during 2004-2007. BP measurements were performed at 6.5 years of age in a sub-cohort of 171 children (35% of the surviving children).

RESULTS

Higher mean daily protein intake (+1 g/kg/day) during postnatal weeks 1-8 was associated with 0.40 (±0.18) SD higher diastolic BP. Higher mean daily carbohydrate intake (+1 g/kg/day) during the same period was associated with 0.18 (±0.05) and 0.14 (±0.04) SD higher systolic and diastolic BP, respectively. No associations were found between infant growth (weight, length) and later BP. Hyperglycemia and its duration during postnatal weeks 1-4 were associated primarily with higher diastolic BP z-scores.

CONCLUSIONS

These findings emphasize the importance of modifiable early-life exposures, such as nutrition and hyperglycemia, in determining long-term outcomes in children born extremely preterm.

Mechanical characterization of arteries affected by fetal growth restriction in guinea pigs (Cavia porcellus)

Fetal growth restriction (FGR) is a perinatal condition associated with a low birth weight that results mainly from maternal and placental constrains. Newborns affected by this condition are more likely to develop in the long term cardiovascular diseases whose origins would be in an altered vascular structure and function defined during fetal development. Thus, this study presents the modeling and numerical simulation of systemic vessels from guinea pig fetuses affected by FGR. We aimed to characterize the biomechanical properties of the arterial wall of FGR-derived the aorta, carotid, and femoral arteries by performing ring tensile and ring opening tests and, based on these data, to simulate the biomechanical behavior of FGR vessels under physiological conditions. The material parameters were first obtained from the experimental data of the ring tensile test. Then, the residual stresses were determined from the ring opening test and taken as initial stresses in the simulation of the ring tensile test. These two coupled steps are iteratively considered in a nonlinear least-squares algorithm to obtain the final material parameters. Then, the stress distribution changes along the arterial wall under physiological pressure were quantified using the adjusted material parameters. Overall, the obtained results provide a realistic approximation of the residual stresses and the changes in the mechanical behavior under physiological conditions.

High Blood Pressure at Early School Age Among Extreme Preterms

BACKGROUND AND OBJECTIVES

Former preterm infants are at increased risk of hypertension with increasing age. Our objective was to identify rates of high blood pressure (BP) (≥90th percentile) and hypertension (BP ≥95th percentile) and associated risk factors among extreme preterm (EPT) infants at 6 to 7 years of age.

METHODS

Assessment included BP and anthropometrics. Comparisons were made by BP ≥90th versus <90th percentile. Regressions were run to identify relative risk (RR) of factors associated with BP ≥90th percentile.

RESULTS

Among 379 EPT infants, 20.6% had systolic high BP, 10.8% systolic hypertension, 21.4% diastolic high BP, and 11.4% diastolic hypertension. Children with systolic high BP had higher rates of BMI, triceps skinfolds >85th percentile, and waist circumference >90th percentile. In regression analyses, weight gain velocity from 18 months to school age (RR = 1.36), and maternal gestational diabetes (MGD) (RR = 2.04) predicted systolic and either systolic and/or diastolic high BP (RR = 1.27 and RR = 1.67). Among children with BMI <85th percentile, 17% had systolic and 19% had diastolic high BP. Regression analysis for normal weight children indicated public insurance (RR = 2.46) and MGD (RR = 2.16) predicted systolic high BP, and MGD (RR = 2.08) predicted either systolic or diastolic high BP.

CONCLUSIONS

Both overweight and normal weight EPT children are at risk for high BP and hypertension. Public insurance, MGD, and weight gain velocity are risk factors. Findings of high BP among EPT children at early school age are worrisome and indicate a need for close follow-up.

Preterm Birth: Long Term Cardiovascular and Renal Consequences

BACKGROUND

Cardiovascular and chronic kidney diseases are a part of noncommunicable chronic diseases, the leading causes of premature death worldwide. They are recognized as having early origins through altered developmental programming, due to adverse environmental conditions during development. Preterm birth is such an adverse factor. Rates of preterm birth increased in the last decades, however, with the improvement in perinatal and neonatal care, a growing number of preterm born subjects has now entered adulthood. Clinical and experimental evidence suggests that preterm birth is associated with impaired or arrested structural or functional development of key organs/systems making preterm infants vulnerable to cardiovascular and chronic renal diseases at adulthood. This review analyzes the evidence of such cardiovascular and renal changes, the role of perinatal and neonatal factors such as antenatal steroids and potential pathogenic mechanisms, including developmental programming and epigenetic alterations.

CONCLUSION

Preterm born subjects are exposed to a significantly increased risk for altered cardiovascular and renal functions at young adulthood. Adequate, specific follow-up measures remain to be determined. While antenatal steroids have considerably improved preterm birth outcomes, repeated therapy should be considered with caution, as antenatal steroids induce long-term cardiovascular and metabolic alterations in animals' models and their involvement in the accelerated cellular senescence observed in human studies cannot be excluded.

Kidneys in 5-year-old preterm-born children: a longitudinal cohort monitoring of renal function

BackgroundBeing aware of the impact of low birth weight on late-onset hypertension, our aim was to describe systolic blood pressure (sBP) and renal function in 3-5-year-old preterm-born children and to determine which perinatal factors or childhood factors were associated with an altered renal function at 5 years in these children.MethodsThis was a prospective longitudinal cohort study of children born at 27-31 weeks of gestation and included at birth and examined at 3, 4, and 5 years of age. The primary outcome was renal function at 5 years: BP, estimated glomerular filtration rate, and albuminuria.ResultsOne hundred and sixty five children were examined, of whom 93 (56.4%) were male. Gestational age was 29.2±1.4 weeks and birth weight was 1,217±331 g. Overall, 25% children had sBP ≥90th percentile at age 3 and 4 years and 11% at 5 years. In multivariate analysis, sBP ≥90th percentile at 5 years was associated with the use of antenatal steroids (OR=0.19(0.05;0.65)). There was a significant association between protein intake on day 28 and sBP at 5 years (β=2.1±1.0, P=0.03). Glomerular filtration rate at 5 years was significantly decreased in case of hyaline membrane disease or necrotizing enterocolitis. High urine albumin was not predictable from one year to another.ConclusionIn preterm-born children, sBP was often high and neonatal protein intake was associated with increased blood pressure during childhood.

Blood Pressure in 6-Year-Old Children Born Extremely Preterm

Background

Advances in perinatal medicine have increased infant survival after very preterm birth. Although this progress is welcome, there is increasing concern that preterm birth is an emerging risk factor for hypertension at young age, with implications for the lifetime risk of cardiovascular disease.

Methods and Results

We measured casual blood pressures (BPs) in a population‐based cohort of 6‐year‐old survivors of extremely preterm birth (<27 gestational weeks; n=171) and in age‐ and sex‐matched controls born at term (n=172). Measured BP did not differ, but sex, age‐, and height‐adjusted median z scores were 0.14 SD higher (P=0.02) for systolic BP and 0.10 SD higher (P=0.01) for diastolic BP in children born extremely preterm than in controls. Among children born extremely preterm, shorter gestation, higher body mass index, and higher heart rate at follow‐up were all independently associated with higher BP at 6 years of age, whereas preeclampsia, smoking in pregnancy, neonatal morbidity, and perinatal corticosteroid therapy were not. In multivariate regression analyses, systolic BP decreased by 0.10 SD (P=0.08) and diastolic BP by 0.09 SD (P=0.02) for each week‐longer gestation.

Conclusions

Six‐year‐old children born extremely preterm have normal but slightly higher BP than their peers born at term. Although this finding is reassuring for children born preterm and their families, follow‐up at older age is warranted.

Cardiac Disease after Pregnancy: A Growing Problem

Pregnancy complications, such as hypertensive disorders or preterm delivery, identify families predisposed to cardiovascular problems at other times in life. Whether the pregnancy complication induces cardiac disease or whether the pregnancy stress unmasks an underlying predisposition remains unclear. However, improved survival following severe pregnancy complications for both the mother and, in particular, the offspring - who is often born preterm - has resulted in a growing cohort of individuals who carry this increased cardiovascular risk. Research to understand the underlying pathological mechanisms that link these conditions might ultimately lead to novel therapeutic or prevention strategies for both cardiovascular and pregnancy disease.

Prevalence of diabetes and obesity in association with prematurity and growth restriction

Intrauterine growth restriction (IUGR) is when fetuses and newborn infants have not reached their true growth potential as genetically defined. Fetuses with IUGR develop in a less than ideal environment that leads to epigenetic changes and marks infants' metabolism for the rest of their lives. Epigenetic changes affect insulin-like growth factor-1 (IGF-1) levels and lead to insulin resistance and ultimately to a metabolic syndrome. The metabolic syndrome is a constellation of illnesses that raise one's risk for type 2 diabetes mellitus, coronary artery disease, and ischemic heart disease, including hypertension, dyslipidemia, central obesity, insulin resistance, and inflammation. The association between IUGR or prematurity and long-term insulin resistance, obesity, hypertension, and metabolic syndrome remains unclear. While studies have shown an association, others have not supported such association. If alteration of intrauterine growth can ultimately lead to the development of metabolic derangements in childhood and adulthood, and if such association is true, then early interventions targeting the health of pregnant women will ensure the health of the population to follow.

Renal outcome in children born preterm with neonatal acute renal failure: IRENEO-a prospective controlled study

OBJECTIVES

Acute kidney injury (AKI) is a severe complication of prematurity, with currently unknown consequences for renal function in childhood. The objective of this study was to search for signs of reduced nephron number in children aged 3-10 years who had been born preterm with neonatal AKI and compare this group to control children.

METHODS

IRENEO was a prospective, controlled study conducted in 2013 in Nantes University Hospital. Children who were born at less than 33 weeks gestational age (GA) and included in the LIFT cohort were eligible for entry. Twenty-five children with AKI (AKI-C) and 49 no-AKI children were matched on a propensity score of neonatal AKI and age. AKI was defined as a serum creatinine level higher than critical values: 1.6 mg/dl (GA 24-27 weeks), 1.1 mg/dl (28-29) and 1 mg/dl (GA 30-32). Renal function was evaluated during childhood.

RESULTS

Mean age of the children at the time of the study was 6.6 years. No difference in microalbuminuria, estimated glomerular filtration rate (GFR) or pulse wave velocity was observed between the two groups. Renal volume was lower in the AKI-C group (57 vs. 68; p = 0.04). In the entire cohort, 10.8 % had a microalbuminuria, and 23 % had a diminished GFR (median 79 ml/min/1.73 m²). The GFR was lower in children with very low birth weight of <1000 g (99 vs. 107 ml/min/1.73 m²; p = 0.04).

CONCLUSION

In children born preterm, neonatal AKI does not seem to influence renal function. However, independent ofAKI, a large proportion of very preterm infants, especially those with very low birth weight, presented with signs of nephron reduction, thus requiring follow-up with a nephrologist.

Weight gain and hypertension at three years of age and older in extremely low birth weight infants

OBJECTIVE

To determine the prevalence and weight gain as a risk factor of hypertension (HTN) at three years of age and older among extremely low birth weight (ELBW) infants.

STUDY DESIGN

Retrospective cohort study of all ELBW infants born and followed up at our institution over 15 years.

RESULTS

204 infants were followed up for [median (inter-quartile range)] 10.2 years (6.9-13.0). Their birth weight and gestational age were (mean±standard deviation) 758±149 g and 26.4±2.1 weeks respectively. At 3 years of age and older, the prevalence of HTN was 7.3% (15/204), and the prevalence of obesity was 13.2% (27/204). Obesity was more prevalent in children with than without HTN [33% (5/15) vs. 12% (22/189); p = 0.01]. In a regression analysis, body mass index (BMI) percentile at 3 years of age and older (p = 0.04) and increase in weight Z scores since birth (p = 0.008) were associated with a higher systolic blood pressure (SBP; R = 0.386, p <  0.001).

CONCLUSION

Obesity is prevalent in ELBW infants at three years of age and older, and it is significantly associated with hypertension. An increase in BMI percentile at ≥3 years of age, and the rate of weight gain since birth among ELBW infants are associated with an increase in SBP.

Blood Pressure in Young Adults Born at Very Low Birth Weight: Adults Born Preterm International Collaboration

Adults born preterm at very low birth weight (VLBW; <1500 g) have higher blood pressure than those born at term. It is not known whether all VLBW adults are at risk or whether higher blood pressure could be attributed to some of the specific conditions underlying or accompanying preterm birth. To identify possible risk or protective factors, we combined individual-level data from 9 cohorts that measured blood pressure in young adults born at VLBW or with a more stringent birth weight criterion. In the absence of major heterogeneity, we performed linear regression analysis in our pooled sample of 1571 adults born at VLBW and 777 controls. Adults born at VLBW had 3.4 mm Hg (95% confidence interval, 2.2-4.6) higher systolic and 2.1 mm Hg (95% confidence interval, 1.3-3.0) higher diastolic pressure, with adjustment for age, sex, and cohort. The difference in systolic pressure was present in men (1.8 mm Hg; 95% confidence interval, 0.1-3.5) but was stronger in women (4.7 mm Hg; 95% confidence interval, 3.2-6.3). Among the VLBW group, blood pressure was unrelated to gestational age, maternal smoking, multiple pregnancy, retinopathy of prematurity, or bronchopulmonary dysplasia. Blood pressure was higher than that of controls among VLBW adults unexposed to maternal preeclampsia. Among those exposed, it was even higher, especially if born appropriate for gestational age. In conclusion, although female sex and maternal preeclampsia are additional risk factors, the risk of higher blood pressure is not limited to any etiologic subgroup of VLBW adults, arguing for vigilance in early detection of high blood pressure in all these individuals.

Rapid Early Growth May Modulate the Association Between Birth Weight and Blood Pressure at 5 Years in the EDEN Cohort Study

Physiological evidence suggests that birth weight (BW) and postnatal growth affect blood pressure (BP) level, independently or in interaction. Their respective roles are difficult to disentangle in epidemiological studies, however, especially when adjusting for final weight. We assessed the portion of the effect of BW on BP at 5 years that was not attributable to postnatal growth and investigated potential interactions between BW and postnatal growth velocity at different time points in the EDEN mother-child study. Collecting a median of 19 weight measurements for each of the 1119 children who completed follow-up enabled us to model instantaneous growth velocity at any age. After computing a BP SD-score at 5 years, adjusted for age, sex, current body mass index, and height, we used multiple linear regression to study its association with age- and sex-specific BW z score, adjusting for several maternal and pregnancy risk factors. We tested interactions between BW categories (small-, appropriate-, and large-for-gestational-age) and weight growth velocities at different ages. The BW z score was negatively and significantly correlated with the systolic BP SD-score at the age of 5 years (r=-0.07, P=0.02). Interactions were found between BW categories and weight growth velocities from 1 to 4 months (P from 0.002 to 0.08) but not at older ages; specifically, children born small for gestational age with a fast weight growth velocity in their first few months of life had the highest absolute systolic BP and SD score values at 5 years. They may need monitoring for cardiovascular risks.

Reprogramming: A Preventive Strategy in Hypertension Focusing on the Kidney

Adulthood hypertension can be programmed in response to a suboptimal environment in early life. However, developmental plasticity also implies that one can prevent hypertension in adult life by administrating appropriate compounds during early development. We have termed this reprogramming. While the risk of hypertension has been assessed in many mother-child cohorts of human developmental programming, interventions necessary to prove causation and provide a reprogramming strategy are lacking. Since the developing kidney is particularly vulnerable to environmental insults and blood pressure is determined by kidney function, renal programming is considered key in developmental programming of hypertension. Common pathways, whereby both genetic and acquired developmental programming converge into the same phenotype, have been recognized. For instance, the same reprogramming interventions aimed at shifting nitric oxide (NO)-reactive oxygen species (ROS) balance, such as perinatal citrulline or melatonin supplements, can be protective in both genetic and developmentally programmed hypertension. Furthermore, a significantly increased expression of gene Ephx2 (soluble epoxide hydrolase) was noted in both genetic and acquired animal models of hypertension. Since a suboptimal environment is often multifactorial, such common reprogramming pathways are a practical finding for translation to the clinic. This review provides an overview of potential clinical applications of reprogramming strategies to prevent programmed hypertension. We emphasize the kidney in the following areas: mechanistic insights from human studies and animal models to interpret programmed hypertension; identified risk factors of human programmed hypertension from mother-child cohorts; and the impact of reprogramming strategies on programmed hypertension from animal models. It is critical that the observed effects on developmental reprogramming in animal models are replicated in human studies.

Postnatal growth in preterm infants and later health outcomes: a systematic review

In preterm infants, poor postnatal growth is associated with adverse neurocognitive outcomes; conversely, rapid postnatal growth is supposedly harmful for future development of metabolic diseases.

CONCLUSION

In this systematic review, observational studies reported consistent positive associations between postnatal weight or head growth and neurocognitive outcomes; however, there was limited evidence from the few intervention studies. Evidence linking postnatal weight gain to later adiposity and other cardiovascular disease risk factors in preterm infants was also limited.

Profiling the preterm or VLBW born adolescent; implications of the Dutch POPS cohort follow-up studies

In 1983, data of a unique nationwide cohort of 1338 very preterm (<32 weeks of gestation) or VLBW (birth weight<1500g) infants in the Netherlands was collected and followed at several ages until they reached the age of 19 years. At 19 years of age a more extensive follow-up study was done, including questionnaires, tests on a computer and a full physical exam. These studies provide insight into how Dutch adolescents at 19 years of age, who were born very preterm or with a very low birth weight (VLBW), reach adulthood. At 19 years, 705 POPS participants participated (74% of 959 still alive). Outcome measures at 19 years included: physical outcomes (e.g. blood pressure), cognition, behavior, quality of life, and impact of handicaps. The POPS participants showed more impairments on most outcome measures at various ages, compared to norm data. Major handicaps remained stable as the children grew older, but minor handicaps and disabilities increased. At 19 years of age, only half (47.1%) of the survivors had no disabilities and no minor or major handicaps. Especially those born small for gestational age (SGA) seem most vulnerable. These long-term results help to support preterm and SGA born children and adolescents in reaching independent adulthood, and stress the need for long term follow-up studies and to promote prevention of disabilities and of preterm birth itself.

The interplay between drugs and the kidney in premature neonates

The kidney plays a central role in the clearance of drugs. However, renal drug handling entails more than glomerular filtration and includes tubular excretion and reabsorption, and intracellular metabolization by cellular enzyme systems, such as the Cytochrome P450 isoenzymes. All these processes show maturation from birth onwards, which is one of the reasons why drug dosing in children is not simply similar to dosing in small adults. As kidney development normally finishes around the 36th week of gestation, being born prematurely will result in even more immature renal drug handling. Environmental effects, such as extra-uterine growth restriction, sepsis, asphyxia, or drug treatments like caffeine, aminoglycosides, or non-steroidal anti-inflammatory drugs, may further hamper drug handling in the kidney. Dosing in preterm neonates is therefore dependent on many factors that need to be taken into account. Drug treatment may significantly hamper postnatal kidney development in preterm neonates, just like renal immaturity has an impact on drug handling. The restricted kidney development results in a lower number of nephrons that may have several long-term sequelae, such as hypertension, albuminuria, and renal failure. This review focuses on the interplay between drugs and the kidney in premature neonates.

Is late-preterm birth a risk factor for hypertension in childhood?

Late-preterm birth is associated with higher rates of neonatal morbidity and mortality and higher health care utilization, but its impact on later life is not well known. In this study, we aimed to evaluate whether late-preterm birth affects blood pressure, renal function, and urinary protein excretion in children later in life. Sixty-five children aged 4 to 13 years born as late-preterm and 65 age- and sex-matched children born full term were evaluated with 24-h ambulatory blood pressure monitoring (ABPM), urinary microalbumin excretion (UAE), and glomerular filtration rate (GFR). All subjects underwent ABPM prospectively. For each gender, daytime, nighttime, and 24-h systolic and diastolic and mean blood pressures (SBP, DBP, and MAP) were transformed to standard deviation scores (SDS). Blood pressure profiles (SBP DBP, and MAP) were considered abnormal when the corresponding SDS values exceeded 1.63. Urinary microalbumin excretion was expressed as milligrams per day, and the value between 30 and 300 mg/day was defined as microalbuminuria (MA). There was no significant difference in the mean GFR and MA levels between late-preterm and term children. 24-h systolic BP SDS, daytime systolic BP SDS, nighttime systolic BP SDS, 24-h diastolic BP SDS, nighttime diastolic BP SDS, 24-h MAP BP SDS, daytime MAP BP SDS, and nighttime MAP BP SDS were found to be significantly higher in late-preterm children compared to term children.

CONCLUSION

We conclude that late-preterm children have higher BP levels, so those children should be followed up carefully by the pediatrician regarding probable hypertension in their future life.

Effect of postnatal maternal protein intake on prenatal programming of hypertension

This study examined whether postnatal maternal dietary protein deprivation during the time of nursing can program hypertension when the offspring are studied as adults. Rats were fed either a 6% or 20% protein diet during the second half of pregnancy and continued on the same diet while rats were nursing their pups. The neonates of all of the rats were cross-fostered to a different mother and studied as adults. Adult rats that had a normal prenatal environment but were reared by mothers fed a low-protein diet until weaning (20%-6%) were hypertensive, had a higher renal Na(+)-K(+)-2Cl(-) cotransporter (NKCC2) and Na(+)-Cl(-) cotransporter (NCC) protein abundance yet a comparable number of glomeruli, and had higher plasma renin and angiotensin II levels compared to control (20%-20%). Rats whose mothers were fed a 6% protein diet and cross-fostered to a different rat fed a 6% protein diet until weaning (6%-6%) were hypertensive, had elevated plasma renin and angiotensin II levels, and had a reduction in nephron number but had NKCC2 and NCC levels comparable to 20% to 20% offspring. The 6% to 20% had blood pressure and glomerular numbers comparable to 20% to 20% rats. The hypertension resulting from prenatal dietary protein deprivation can be normalized by improving the postnatal environment. Combined prenatal and postnatal maternal dietary protein deprivation and maternal dietary protein deprivation while nursing alone (20%-6%) results in hypertension, but the mechanism for the hypertension in these groups is different.

Is very preterm birth a risk factor for adult cardiometabolic disease?

The first infants to experience modern pre- and neonatal care are now in their thirties, an age at which the incidence of cardiometabolic disease is low. However, data from cohorts born preterm prior to the introduction of modern care suggest an increased risk of type 2 diabetes. For young adult cohorts of former very small or very preterm infants, there is accumulating evidence of increased risk factors for later cardiovascular disease, including higher blood pressure, lower lean body mass, impaired glucose regulation, and perhaps a more atherogenic lipid profile. Regarding lifestyle, adults born very small or very preterm undertake less non-conditioning physical activity and may have a lower intake of fruit and milk products. Any intervention reducing risk factors, in particular blood pressure and low physical activity, would have a substantial potential to reduce the lifetime disease burden in small preterm infants. There are now enough data to warrant an expert evaluation of the level of evidence for cardiometabolic disease in individuals born very small or very preterm, which has possible public health implications.

Low birthweight and risk of albuminuria in living kidney donors

Low birthweight is linked to hypertension, chronic kidney disease and even end-stage renal disease. We hypothesized that living kidney donors born with lower birthweight may be at increased risk of hypertension, albuminuria, or reduced GFR beyond what is typical following uninephrectomy. Two hundred fifty-seven living kidney donors who donated at the University of Minnesota between 1967 and 2005 underwent iohexol GFR and urinary albumin excretion measurements. Predictors of iohexol GFR <60 mL/min/1.73 m(2), albuminuria, and hypertension were examined using logistic regression. Predictors examined include age at GFR measurement, time since donation, BMI, gender, serum creatinine level (at donation and GFR measurement), systolic and diastolic blood pressure, race, and birthweight. The latter was obtained through self-report and verified through birth certificates and family members. Older age, higher BMI, and time from donation were associated with reduced GFR. Older age and higher BMI were also associated with hypertension. Birthweight was not associated with GFR <60 mL/min/1.73 m(2): OR=0.70, 95% CI (0.28, 1.74), p = 0.45 or hypertension: OR=0.92, 95% CI (0.46, 1.84), p = 0.82 but was associated with albuminuria: OR=0.37, 95% CI (0.15, 0.92), p = 0.03. These data further strengthen the link between low birthweight and potential adverse renal outcomes.

Long term cardiovascular consequences of chronic lung disease of prematurity

Pulmonary arterial (PA) hypertension in preterm infant is an important consequence of chronic lung disease of prematurity (CLD) arising mainly due to impaired alveolar development and dysregulated angiogenesis of the pulmonary circulation. Although PA pressure and resistance in these children normalise by school age, their pulmonary vasculature remains hyper-reactive to hypoxia until early childhood. Furthermore, there is evidence that systemic blood pressure in preterm born children with or without CLD is mildly increased at school age and in young adulthood when compared to term-born children. Arterial stiffness may be increased in CLD survivors due to increased smooth muscle tone of the pre-resistance and resistance vessels rather than the loss of elasticity in the large arteries. This review explores the long term effects of CLD on the pulmonary and systemic circulations along with their clinical correlates and therapeutic approaches.

Feeding preterm infants today for later metabolic and cardiovascular outcomes

Preterm birth continues to contribute disproportionately to neonatal morbidity and subsequent physical and neurodevelopmental disabilities. Epidemiologic studies have described additional long-term health consequences of preterm birth such as an increased risk of hypertension and insulin resistance in adult life. It is not known whether the influence of infant and childhood growth rates and early nutrition on long-term outcomes is the same or different among preterm infants and neonates with intrauterine growth restriction. Our goal is to review the effects of fetal growth, postnatal growth, and early nutrition on long-term cardiovascular and metabolic outcomes in preterm infants. Present evidence suggests that even brief periods of relative undernutrition during a sensitive period of development have significant adverse effects on later development. Our review suggests that growth between birth and expected term and 12-18 months post-term has no significant effect on later blood pressure and metabolic syndrome, whereas reduced growth during hospitalization significantly impacts later neurodevelopment. In contrast, growth during late infancy and childhood appears to be a major determinant of later metabolic and cardiovascular well being, which suggests that nutritional interventions during this period are worthy of more study. Our review also highlights the paucity of well-designed, controlled studies in preterm infants of the effects of nutrition during hospitalization and after discharge on development, the risk of developing hypertension, or insulin resistance.

The relationship between birth weight and blood pressure in childhood: a population-based study

BACKGROUND

Low birth weight has been associated with increased risk of hypertension later in life. The aim of this study was to evaluate the association between birth weight and blood pressure (BP) in healthy 9- to 10-year-old Icelandic children.

METHODS

Each child underwent 4 seated BP measurements, and the BP percentile was calculated from the mean of the 4 measurements. Height and weight were measured and birth weight retrieved from the Icelandic Birth Registry. Birth measures and anthropometric data were correlated with BP and BP percentiles. Multivariable linear regression was employed to examine the association between BP and birth measures.

RESULTS

Of 857 children with complete data, 445 were female (51.9%). The mean BP was 112/64 mm Hg in males and 111/63 mm Hg in females. The mean birth weight was 3714 ± 620 g. No correlation was found between birth weight and absolute BP values. A significant negative correlation between birth weight and both systolic (r = -0.09, P = 0.005) and diastolic (r = -0.08, P = 0.014) BP percentiles was observed. Gestational age did not correlate with BP.

CONCLUSION

In contrast to many previous studies, we found no association between birth weight and absolute BP in children. However, we observed a statistically significant negative correlation between birth weight and BP percentiles. The lack of standardized BP values may partly explain the conflicting results of previous studies in children, and we suggest that BP percentiles be examined more thoroughly in association with birth weight.

Developmental programming of hypertension and kidney disease

A growing body of evidence supports the concept that changes in the intrauterine milieu during "sensitive" periods of embryonic development or in infant diet after birth affect the developing individual, resulting in general health alterations later in life. This phenomenon is referred to as "developmental programming" or "developmental origins of health and disease." The risk of developing late-onset diseases such as hypertension, chronic kidney disease (CKD), obesity or type 2 diabetes is increased in infants born prematurely at <37 weeks of gestation or in low birth weight (LBW) infants weighing <2,500 g at birth. Both genetic and environmental events contribute to the programming of subsequent risks of CKD and hypertension in premature or LBW individuals. A number of observations suggest that susceptibility to subsequent CKD and hypertension in premature or LBW infants is mediated, at least in part, by reduced nephron endowment. The major factors influencing in utero environment that are associated with a low final nephron number include uteroplacental insufficiency, maternal low-protein diet, hyperglycemia, vitamin A deficiency, exposure to or interruption of endogenous glucocorticoids, and ethanol exposure. This paper discusses the effect of premature birth, LBW, intrauterine milieu, and infant feeding on the development of hypertension and renal disease in later life as well as examines the role of the kidney in developmental programming of hypertension and CKD.

Low Birth Weight due to Intrauterine Growth Restriction and/or Preterm Birth: Effects on Nephron Number and Long-Term Renal Health

Epidemiological studies have clearly demonstrated a strong association between low birth weight and long-term renal disease. A potential mediator of this long-term risk is a reduction in nephron endowment in the low birth weight infant at the beginning of life. Importantly, nephrons are only formed early in life; during normal gestation, nephrogenesis is complete by about 32–36 weeks, with no new nephrons formed after this time during the lifetime of the individual. Hence, given that a loss of a critical number of nephrons is the hallmark of renal disease, an increased severity and acceleration of renal disease is likely when the number of nephrons is already reduced prior to disease onset. Low birth weight can result from intrauterine growth restriction (IUGR) or preterm birth; a high proportion of babies born prematurely also exhibit IUGR. In this paper, we describe how IUGR and preterm birth adversely impact on nephrogenesis and how a subsequent reduced nephron endowment at the beginning of life may lead to long-term risk of renal disease, but not necessarily hypertension.