Risk of high blood pressure among young men increases with the degree of immaturity at birth

Adverse Pregnancy Conditions, Infertility, and Future Cardiovascular Risk: Implications for Mother and Child

Adverse pregnancy conditions in women are common and have been associated with adverse cardiovascular and metabolic outcomes such as myocardial infarction and stroke. As risk stratification in women is often suboptimal, recognition of non-traditional risk factors such as hypertensive disorders of pregnancy and premature delivery has become increasingly important. Additionally, such conditions may also increase the risk of cardiovascular disease in the children of afflicted women. In this review, we aim to highlight these conditions, along with infertility, and the association between such conditions and various cardiovascular outcomes and related maternal risk along with potential translation of risk to offspring. We will also discuss proposed mechanisms driving these associations as well as potential opportunities for screening and risk modification.

Cardiometabolic risk factors in young adults who were born preterm

Adults who were born preterm with a very low birth weight have higher blood pressure and impaired glucose regulation later in life compared with those born at term. We investigated cardiometabolic risk factors in young adults who were born at any degree of prematurity in the Preterm Birth and Early Life Programming of Adult Health and Disease (ESTER) Study, a population-based cohort study of individuals born in 1985–1989 in Northern Finland. In 2009–2011, 3 groups underwent clinical examination: 134 participants born at less than 34 gestational weeks (early preterm), 242 born at 34–36 weeks (late preterm), and 344 born at 37 weeks or later (controls). Compared with controls, adults who were born preterm had higher body fat percentages (after adjustment for sex, age, and cohort (1985–1986 or 1987–1989), for those born early preterm, difference = 6.2%, 95% confidence interval (CI): 0.4, 13.2; for those born late preterm, difference = 8.0%, 95% CI: 2.4, 13.8), waist circumferences, blood pressure (for those born early preterm, difference = 3.0 mm Hg, 95% CI: 0.9, 5.1; for those born late preterm, difference = 1.7, 95% CI: −0.1, 3.4), plasma uric acid levels (for those born early preterm, difference = 20.1%, 95% CI: 7.9, 32.3; for those born late preterm, difference = 20.2%, 95% CI: 10.7, 30.5), alanine aminotransferase levels, and aspartate transaminase levels. They were also more likely to have metabolic syndrome (for those born early preterm, odds ratio = 3.7, 95% CI: 1.6, 8.2; for those born late preterm, odds ratio = 2.5, 95% CI: 1.2, 5.3). Elevated levels of conventional and emerging risk factors suggest a higher risk of cardiometabolic disease later in life. These risk factors are also present in the large group of adults born late preterm.

Birth weight and risk factors for cardiovascular disease and type 2 diabetes in US children and adolescents: 10 year results from NHANES

Previous studies have shown that birth weight and other birth characteristics may be associated with risk for type 2 diabetes and cardiovascular disease (CVD) later in life; however, results using large US national survey data are limited. Our goal was to determine the aforementioned associations using nationally representative data. We studied children and adolescents 6-15 years using data from the National Health and Nutrition Examination Survey cycles 2001-2010. Survey and examination data included demographic and early childhood characteristics, current health status, physical activity information, anthropometric measurements, dietary data (total energy, saturated fat, sodium, and sugar intakes), biomarkers related to selected risk factors of CVD [systolic blood pressure (SBP), plasma C-reactive protein (CRP) and lipid profiles], and type 2 diabetes [fasting glucose, insulin, and homeostasis model assessment (HOMA)]. Birth weight (proxy-reported) was inversely associated with SBP among girls; SBP levels increased 1.4 mmHg for each 1,000 g decrease in birth weight (p = 0.003) after controlling for potential confounders. Birth weight was not associated with levels of CRP or lipid profiles across the three racial groups. In addition, birth weight was inversely related to levels of fasting insulin and HOMA among non-Hispanic Whites; for each 1,000 g decrease in birth weight, fasting insulin levels increased 9.1% (p = 0.007) and HOMA scores increased 9.8% (p = 0.007). Birth weight was inversely associated with the levels of SBP, fasting insulin, and HOMA. These results support a role for birth weight, independent of the strong effects of current body weight status, in increasing risk for CVD and type 2 diabetes.

Gestational age at birth affects maturation of baroreflex control

OBJECTIVES

To assess the effect of prone sleeping, the major risk factor for sudden infant death syndrome, in the control of blood pressure (BP) in preterm infants born across a range of gestational ages.

STUDY DESIGN

Daytime polysomnography was performed at 2-4 weeks, 2-3 months, and 5-6 months postterm age. The participants were 21 very preterm (mean gestation 29.4 ± 0.3 weeks), 14 preterm (mean gestation 33.1 ± 0.3 weeks), and 17 term (mean gestation 40.1 ± 0.3 weeks). BP was measured via a Finometer cuff (Finapres Medical Systems, Amsterdam, The Netherlands) placed around the wrist. Data were recorded both supine and prone. Baroreflex sensitivity (BRS) was calculated via cross-spectral analysis of spontaneous fluctuations in BP.

RESULTS

BRS was lower in the prone position in very preterm infants at 2-4 weeks in active sleep (P < .05). Maturation of BRS was delayed in very preterm compared with both preterm and term infants.

CONCLUSIONS

Maturation of BRS after term-equivalent age is altered in very preterm infants. Reduced BRS may result in an impaired ability of very preterm infants to respond to cardiovascular stress during infancy and may predispose them to cardiovascular disease later in life.

Cardiovascular dysfunction in adult mice following postnatal intermittent hypoxia

BACKGROUND

Ex-premature infants are at higher risk for hypertension and cardiovascular disease as adults, although the mechanisms underlying such increased risks are unknown. We hypothesize that postnatal exposure to intermittent hypoxia (IH) leads to cardiovascular dysfunction in adulthood with alterations of the renin-angiotensin pathway.

METHODS

Neonatal mice were exposed to IH for 4 wk. At the age of 3 mo, various cardiovascular measurements were obtained.

RESULTS

IH-exposed mice exhibited higher systolic blood pressure, impaired baroreflex responses, and decreased heart rate variability. Furthermore, IH-exposed mice manifested evidence of endothelial dysfunction, as shown by reduced reperfusion indices after tail vessel occlusion and impaired vasodilatory responses to acetylcholine. CD31(+) endothelial cells isolated from mesenteric arteries of IH-exposed mice expressed higher levels of angiotensin-converting enzyme and reactive oxygen species; plasma angiotensin-II levels were also significantly higher in these animals. In addition, DNA methylation patterns of the Ace1 and the Agt genes in these cells were congruent with their expression patterns.

CONCLUSION

Our results suggest that exposures to postnatal IH alter the normal development of the renin-angiotensin system and promote the occurrence of cardiovascular dysfunction during adulthood in mice.

Components of the metabolic syndrome in early childhood in very-low-birth-weight infants

BACKGROUND/AIMS

Term small-for-gestational-age and preterm born infants have an increased prevalence of metabolic syndrome components already in childhood. Data in very-low-birth-weight (VLBW) children are limited. We investigated the prevalence of metabolic syndrome components in VLBW infants at 2 years of corrected age.

METHODS

We included 38 children, participating in the Neonatal Insulin Replacement Therapy in Europe (NIRTURE) trial, a randomized controlled trial of early insulin therapy in VLBW infants. Metabolic syndrome components were defined as: body mass index SDS >2; blood pressure (systolic and/or diastolic) ≥ 90th percentile; triglycerides ≥ 0.98 mmol/l; high-density lipoprotein (HDL) cholesterol ≤ 1.03 mmol/l; glucose ≥ 5.6 mmol/l.

RESULTS

Two children (5%) had three metabolic syndrome components, 13 children (34%) had two components, and 11 children (29%) one component. 63% had raised blood pressure (prevalence higher in boys), 32% low HDL, and 30% high triglycerides (prevalence lower in early insulin group). In children with body mass index SDS <0, insulin-treated children had higher HDL than children with standard care. Systolic blood pressure was correlated with growth between term and 2 years of corrected age.

CONCLUSIONS

VLBW infants already have a high prevalence of metabolic syndrome components at 2 years of corrected age. Early insulin treatment could have long-term benefits for some of these components.

Alterations in viscoelastic properties following premature birth may lead to hypertension and cardiovascular disease development in later life

The aim of this review was to identify the underlying relationship between preterm birth and the development of cardiovascular diseases. Preterm birth significantly affects the elastin content and viscoelastic properties of the vascular extracellular matrix in human arteries. Inadequate elastin synthesis during early development may cause a permanent increase in arterial stiffness in adulthood.

CONCLUSION

Early and permanent alterations in viscoelastic properties may lead to hypertension and cardiovascular disease development in adults born prematurely.

Elevated blood pressure in preterm-born offspring associates with a distinct antiangiogenic state and microvascular abnormalities in adult life

Preterm-born individuals have elevated blood pressure. We tested the hypothesis that this associates with an enhanced antiangiogenic circulating profile and that this association is mediated by variations in capillary density. We studied 204 adults aged 25 years (range, 20-30 years), of which 102 had been followed up prospectively since very preterm birth (mean gestational age, 30.3±2.5 weeks) and 102 were born term to uncomplicated pregnancies. A panel of circulating biomarkers, including soluble endoglin and soluble fms-like tyrosine kinase-1, were compared between groups and related to perinatal history and adult cardiovascular risk. Associations with cardiovascular phenotype were studied in 90 individuals who had undergone detailed assessment of microvascular, macrovascular, and cardiac structure and function. Preterm-born individuals had elevations in soluble endoglin (5.64±1.03 versus 4.06±0.85 ng/mL; P<0.001) and soluble fms-like tyrosine kinase-1 (88.1±19.0 versus 73.0±15.3 pg/mL; P<0.001) compared with term-born individuals, proportional to elevations in resting and ambulatory blood pressure, as well as degree of prematurity (P<0.05). Maternal hypertensive pregnancy disorder was associated with additional increases in soluble fms-like tyrosine kinase-1 (P=0.002). Other circulating biomarkers, including those of inflammation and endothelial activation, were not related to blood pressure. There was a specific graded association between soluble endoglin and degree of functional and structural capillary rarefaction (P=0.002 and P<0.001), and in multivariable analysis, there were capillary density-mediated associations between soluble endoglin and blood pressure. Preterm-born individuals exhibit an enhanced antiangiogenic state in adult life that is specifically related to elevations in blood pressure. The association seems to be mediated through capillary rarefaction and is independent of other cardiovascular structural and functional differences in the offspring.

Premature guinea pigs: a new paradigm to investigate the late-effects of preterm birth

Preterm birth is common and the associated short-term morbidity well described. The adult-onset consequences of preterm birth are less clear, but cardiovascular and metabolic health may be adversely affected. Although large animal models of preterm birth addressing important short-term issues exist, long-term studies are hampered by significant logistical constraints. Current small animal models of prematurity require terminal caesarean section of the mother; both caesarean birth and early maternal care modify offspring adult cardio-metabolic function. We describe a novel method for inducing preterm labour in guinea pigs. With support comparable to that received by moderately preterm human infants, preterm pups are viable. Growth trajectories between preterm and term-born pups differ significantly; between term equivalent age and weaning ex-preterm animals demonstrate increased weight and ponderal index. We believe this novel paradigm will significantly improve our ability to investigate the cardio-metabolic sequelae of preterm birth throughout the life course and into the second generation.

Prematurity and programming of cardiovascular disease risk: a future challenge for public health?

There is substantial epidemiological evidence linking low birth weight with adult cardiometabolic disease risk factors. This has led to the concept of 'early life programming' or the 'developmental origins of disease' which proposes that exposure to adverse conditions during critical stages of early development results in compensatory mechanisms predicted to aid survival. There is growing evidence that preterm infants, many of whom are of low birth weight, are also at increased risk of adult cardiometabolic disease. In this article, we provide a broad overview of the evidence linking preterm birth and cardiovascular disease risk and discuss potential consequences for public health.

Cardiovascular risk factors in adolescents born preterm

BACKGROUND

Adolescents and adults born as small preterm infants show more pronounced risk factors of cardiovascular disease. Whether similar risks apply across all degrees of preterm birth is poorly known.

METHODS

We studied the association between preterm birth and cardiovascular risk factors in 6642 16-year-old adolescents of the population-based Northern Finland Birth Cohort 1986. Of these, 79 (1.2%) were born at <34 gestational weeks (early preterm), 238 (3.6%) at 34 to 36 weeks (late preterm), and 6325 at term (controls).

RESULTS

Girls born early preterm had 6.7 mm Hg (95% confidence interval: 3.1-10.2) higher systolic blood pressure (BP) and 3.5 mm Hg (1.1-5.8) higher diastolic BP, but no difference in serum lipid levels compared with control girls. Boys showed no differences in BP, but boys born early preterm had 6.7% (0.2%-13.7%) higher total cholesterol, 11.7% (2.1%-22.3%) higher low-density lipoprotein cholesterol, and 12.3% (3.1%-22.4%) higher apolipoprotein B concentrations. The differences were similar (BP) or stronger (lipids) when adjusted for maternal smoking, birth weight SD score, parental education, pubertal stage, BMI, and lifestyle. There were similar associations with length of gestation as a continuous variable. Accordingly, mean differences between late preterm and controls were in the same direction but weaker, although most were not statistically significant.

CONCLUSIONS

Preterm birth was associated with elevated BP in adolescent girls and an atherogenic lipid profile in boys. Because these associations were strongest among those born early preterm, our findings are consistent with a dose-response relationship between shorter length of gestation and cardiovascular risk factors.

Increased systemic blood pressure and arterial stiffness in young adults born prematurely

Recent studies have shown that a low birth weight is a risk factor for increased systemic blood pressure (BP) in adulthood. Further, systemic BP and arterial stiffness (AS) are reported to be increased in adolescents born prematurely. The purpose of this study was to characterize systemic BP and AS in young adults born preterm. Systemic BP was measured using an automated oscillometric device. AS was assessed by measuring the right carotid-radial pulse wave velocity (PWV) using a validated non-invasive automated method. Systemic BP, pulse pressure, and PWV [mean (confidence intervals)] were compared between 16 adults (age 21 years) born preterm (age at birth 32 weeks of gestation) with a birth weight (1710 g) appropriate for their gestational age and 15 adults (21 years) born at term (40 weeks of gestation) with a birth weight (3430 g) appropriate for their gestational age. Adults born preterm had a significantly higher systolic BP [122 mmHg (114-144) v. 112 (106-127)], mean BP [89 mmHg (86-98) v. 84 (81-91)], diastolic BP [69 mmHg (66-76) v. 65 (62-78)], pulse pressure [54 mmHg (47-72) v. 47 (42-60)], and PWV [7 m/s (6.3-8.6) v. 6.4 (5.8-8)] than did those born at term. Our findings suggest that young adults with a low birth weight due to preterm birth have increased systemic BP and AS. Accordingly, preterm birth may predispose individuals to cardiovascular diseases in adulthood due to increased AS.

Aortic growth arrest after preterm birth: a lasting structural change of the vascular tree

Young people who are born very preterm exhibit a narrower arterial tree as compared with people born at term. We hypothesized that such arterial narrowing occurs as a direct result of premature birth. The aim of this study was to compare aortic and carotid artery growth in infants born preterm and at term. Observational and longitudinal cohort study of 50 infants (21 born very preterm, all appropriate for gestational age, 29 controls born at term) was conducted. Diameters of the upper abdominal aorta and common carotid artery were measured with ultrasonography at three months before term, at term and three months after term-equivalent age. At the first assessment, the aortic end-diastolic diameter (aEDD) was slightly larger in very preterm infants as compared with fetal dimensions. Fetal aortic EDD increased by 2.6 mm during the third trimester, whereas very preterm infants exhibited 0.9 mm increase in aEDD during the same developmental period (P < 0.001 for group difference). During the following 3-month period, aortic growth continued unchanged (+0.9 mm) in very preterm infants, whereas postnatal growth in term controls slowed down to +1.3 mm (P < 0.001 v. fetal aortic growth). At the final examination, aEDD was 22% and carotid artery EDD was 14% narrower in infants born preterm compared with controls, also after adjusting for current weight (P < 0.01). Aortic and carotid artery growth is impaired after very preterm birth, resulting in arterial narrowing. Arterial growth failure may be a generalized vascular phenomenon after preterm birth, with implications for cardiovascular morbidity in later life.

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.

Albuminuria and sodiuria in IUGR children

OBJECTIVE

Intrauterine growth restriction (IUGR) is associated with hyperfiltration, glomerulosclerosis and albuminuria. Albuminuria may further lead to tubulointerstitial inflammation, fibrosis and tubular atrophy. The time at which this may occur is unknown. This study was designed to assess the relationship between glomerular and tubular damage in IUGR children.

METHODS

We enrolled 50 children, 25 IUGR, categorized by estimated fetal weight <10th percentile and umbilical artery pulsatility index >2 SD, and 25 appropriate for gestational age (AGA) controls at 18 months of age. We compared albuminuria among IUGR and AGA children, to assess the relationship between albuminuria and contemporary sodium and lysozyme excretion, as a measure of tubular damage.

RESULTS

The albumin-creatinine (mg/g) and sodium-creatinine (μM/L) ratios (3.12 and 441.3, versus 1.39 and 226.1 in AGA; p = 0.002 and p = 0.012, respectively) were significantly higher in the IUGR subjects compared with AGA children, and significantly correlated (rho = 0.593, p = 0.002). Conversely, urinary lysozyme was undetectable or in normal excretion range.

CONCLUSIONS

Our results show glomerulosclerosis and albuminuria in IUGR children aged 18 months. Elevated sodium excretion in the absence of abnormal lysozymuria may represent a epiphenomenon of glomerulosclerosis and of albuminuria.

Cerebrovascular and ischemic heart disease in young adults born preterm: a population-based Swedish cohort study

Preterm birth is associated with overall cardiovascular mortality in young adulthood, but which specific conditions that underlie this association is unknown. We studied mortality and morbidity from cerebrovascular and ischemic heart disease in individuals born preterm. In a nationwide Swedish study, we included 1,306,943 individuals without congenital malformations born between 1983 and 1995, followed from 15 years of age to December 31st, 2010. Of these, 73,489 (5.6 %) were born preterm (<37 weeks of gestation). Cox proportional hazards regression analysis was used to calculate hazard ratios (HR) with 95 % confidence intervals (CI), after adjusting for maternal characteristics and birth weight for gestational age. Of 955 incident cases of cerebrovascular disease, 58 (6.1 %) occurred in preterm born subjects. The corresponding numbers of ischemic heart disease cases were 180 and 13 (7.2 %), respectively. Birth before 32 weeks was associated with a nearly twofold increased risk of cerebrovascular disease; adjusted HR, (95 % CI) = 1.89 (1.01-3.54) compared to term born individuals, whereas individuals born at 32-36 weeks were not at increased risk. Preterm birth was not associated with later ischemic heart disease; no cases of ischemic heart disease were recorded among those born before 32 weeks and the HR (95 % CI) for those born at 32-36 weeks of gestation was 1.45 (0.81-2.57), compared to term-born individuals. Birth before 32 weeks is associated with increased risk of cerebrovascular disease in young adulthood. Our data suggest that cardiovascular health promotion in follow-up programs after very preterm birth may be beneficial.

Neonatal IGF-1/IGFBP-1 axis and retinopathy of prematurity are associated with increased blood pressure in preterm children

Aim

Preterm children are at risk of developing increased blood pressure (BP). We evaluated possible associations between BP, early insulin-like growth factor-1 (IGF-1) and IGF-binding protein-1 (IGFBP-1) levels and retinopathy of prematurity (ROP) in preterm children.

Methods

The study included 32 infants: median gestational age 28.1 weeks (range 24.6–31.3) and birthweight standard deviation scores (SDS) (±SD) 1.0 ± 2.7. IGF-1 and IGFBP-1 at postnatal weeks 32.6–34.6 and ROP stages were established after birth. BP was measured at the age of 4 years. The ratio (IGF-1)²/IGFBP-1 was created to investigate the influence of both IGF-1 and IGFBP-1 to later BP.

Results

Diastolic BP correlated with IGFBP-1, inversely correlated with IGF-1 and IGF-1²/IGFBP-1 (r = −0.71, p < 0.0001) and positively correlated with catch-up growth velocity from lowest weight SDS to age 36.5 weeks (r = 0.48, p < 0.01), independent of gestational age. Children with moderate-to-severe ROP as neonates had higher mean arterial BP [78 (±95%CI 74–83) vs 71 (±95%CI 68–75) mm Hg, p < 0.05] adjusted for gestational age and birthweight SDS compared to children diagnosed with no to mild ROP.

Conclusion

Low neonatal IGF-1²/IGFBP-1 and severe ROP were associated with higher BP in 4-year-old children born very preterm and may thus predict future cardiovascular morbidity.

Aortic intima-media thickness measured by trans-abdominal ultrasound as an early life marker of subclinical atherosclerosis

Atherosclerosis is a chronic inflammatory process that begins in early life. Improved identification of markers of early atherosclerosis via neonatal aortic intima-media thickness (aIMT) measurement may allow the development of interventions to prevent or reduce later cardiovascular disease.

CONCLUSION

Using aIMT, studies have shown that antenatal factors such as intra-uterine growth retardation, prematurity, maternal factors and inflammation are associated with early cardiovascular changes.

Long-term impact of preterm birth on exercise capacity in healthy young men: a national population-based cohort study

Background

Increasing numbers of survivors of preterm birth are growing into adulthood today. Long-term health-effects of prematurity are still poorly understood, but include increased risk for diabetes, obesity and cardiovascular diseases in adult life. To test if reduced physical fitness may be a link in the causal chain of preterm birth and diseases in later life, the association of preterm birth and adult exercise capacity was investigated. The hypothesis was that preterm birth contributes independently of other risk factors to lower physical fitness in adulthood.

Methods and Findings

Population-based national cohort study of all males conscripting for military service in 1993–2001 and born in Sweden 1973–1983, n = 218,820. Data were retrieved from the Swedish Conscript Register, the Medical Birth Register and the Population and Housing Census 1990. Primary outcome was the results from maximal exercise test (W_max in Watt) performed at conscription. Association to perinatal and socioeconomic risk factors, other co-variates and confounders were analysed. General linear modelling showed that preterm birth predicted low W_max in a dose-response related pattern, with 25 Watt reduction in W_max for the lowest gestational ages, those born ≤27 weeks. Low birth weight for gestational age also independently predicted low W_max compared to normal and high birth weight (32 Watt reduction for those with a birth weight Standard Deviation Score <2). Low parental education was significantly associated with reduced W_max (range 17 Watt), as well as both low and high current BMI, with severe obesity resulting in a 16 Watt deficit compared to W_max top performance.

Conclusion

Being born preterm as well as being born small for gestational age predicts low exercise capacity in otherwise healthy young men. The effect size of being born preterm equal or exceed that of other known risk factors for unfitness in adults, such as low parental education and overweight.

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.

Increased adiposity in adults born preterm and their children

Background

Preterm birth is associated with abnormalities in growth, body composition, and metabolism during childhood, but adult data are scarce and none exist for their offspring. We therefore aimed to examine body composition and cardiovascular risk factors in adults born preterm and their children.

Methods

A cohort of 52 adults (aged 35.7 years, 54% female, 31 born preterm) and their term-born children (n=61, aged 8.0 years, 54% female, 60% from a preterm parent) were studied. Auxology and body composition (whole-body dual-energy X-ray absorptiometry) were measured, and fasting blood samples taken for metabolic and hormonal assessments.

Results

Adults born preterm had greater abdominal adiposity, displaying more truncal fat (p=0.006) and higher android to gynoid fat ratio (p=0.004). Although women born preterm and at term were of similar weight and BMI, men born preterm (n=8) were on average 20 kg heavier (p=0.010) and of greater BMI (34.2 vs 28.4 kg/m²; p=0.021) than men born at term (n=16). Adults born preterm also displayed a less favourable lipid profile, including lower HDL-C concentrations (p=0.007) and greater total cholesterol to HDL-C ratio (p=0.047). Children of parents born preterm tended to have more body fat than the children of parents born at term (21.3 vs 17.6%; p=0.055). Even after adjustment for mean parental BMI, children of parents born preterm had altered fat distribution, with more truncal fat (p=0.048) and greater android to gynoid fat ratio (p=0.009).

Conclusions

Adults born preterm, particularly men, have markedly increased fat mass and altered fat distribution. A similar increase in abdominal adiposity was observed in the term born offspring of parents born preterm, indicating that adverse outcomes associated with preterm birth may extend to the next generation.

Relative intima-media thickening after preterm birth

AIM

Preterm infants are at increased risk of early arterial growth arrest and cardiovascular mortality. We assessed intima-media thickness (IMT) - an early marker of accelerated vascular ageing - in very preterm infants.

METHODS

Longitudinal cohort study of 21 very preterm and 29 term infants, all with appropriate birthweights. Intima-media thickness was assessed by M-Mode ultrasound of the aorta and carotid arteries at three occasions during a 6-month period corresponding to the third trimester of pregnancy and ending 3 months after term equivalent age.

RESULTS

No differences in absolute aortic or carotid IMT were found. However, in relation to vessel lumen diameter, the IMT switched from being narrower in preterm infants, compared with foetuses at 28 weeks of gestation, to being significantly thicker in both the aorta and carotid artery in older infants born preterm, compared with term controls of equivalent postmenstrual age. Although the aortic and carotid artery diameters increased significantly with postnatal age, IMT did not.

CONCLUSION

In relation to vessel diameter, subjects born preterm show thicker intima-media in the great arteries than infants born at term. It remains to be established whether this relative intima-media thickening persists and may be a risk marker for future cardiovascular disease.

Repeat antenatal steroid exposure and later blood pressure, arterial stiffness, and metabolic profile

OBJECTIVE

To determine the relationship between repeat courses of antenatal corticosteroids (ACS) and risk factors for cardiovascular disease in adolescents and young adults.

STUDY DESIGN

We assessed body mass index, blood pressure, arterial stiffness, blood lipids, and insulin resistance (IR) in a Swedish population-based cohort (n = 100) at a median age of 18 (range 14-26) years. Fifty-eight subjects (36 males) had been exposed to 2-9 weekly courses of antenatal betamethasone and 42 (23 males) were unexposed subjects matched for age, sex, and gestational age (GA).

RESULTS

There were no significant differences between the groups regarding body mass index, systolic or diastolic blood pressures, arterial stiffness measured by augmentation index, blood lipids, IR, or morning cortisol levels either in simple regression or in multivariable models. However, more subjects with elevated augmentation index had been exposed to repeat courses of ACS (n = 7) compared with unexposed subjects (n =1, P = .06), and glucose, insulin, and IR correlated inversely to GA at start of ACS (P < .01).

CONCLUSIONS

Repeat courses of ACS did not correlate to adverse cardiovascular risk profile in adolescence and young adulthood, but long-standing effects on the arterial tree and glucose metabolism, the latter dependent on GA at ACS exposure, cannot be excluded. These observations have clinical implications for the ongoing discussion on short-term benefits and long-term safety of repeat ACS treatment.

Cardiovascular function in children born very preterm after intrauterine growth restriction with severely abnormal umbilical artery blood flow

AIMS

Low birthweight has been linked to increased cardiovascular risk in adulthood. We evaluated the effect on cardiovascular outcome of intrauterine growth restriction (IUGR) with abnormal fetal blood flow in children born very preterm.

METHODS

Blood pressure, cardiac function and size, diameters, distensibility, and stiffness of the abdominal aorta, carotid, and popliteal arteries, and endothelial function were assessed non-invasively in 7-year-old children (n = 32) born very preterm with IUGR, with birthweight (median, range) 650 g (395-976 g) and gestational age 27 weeks (24-29 weeks). In addition, intima-media thickness was measured in the carotid artery. Controls were matched for gender and age and had birthweight appropriate-for-gestational-age (AGA). The study included 32 preterm-AGA children with birthweight 1010 g (660-1790) g and 32 term-AGA children with birthweight 3530 g (3000-4390) g.

RESULTS

Preterm-IUGR children had lower microvascular response to acetylcholine, lower aortic stiffness, and higher distensibility compared with the preterm-AGA group (p = 0.019, p = 0.001, and p < 0.001, respectively) and lower carotid intima-media thickness compared with the term-AGA group (p = 0.047). The highest aortic β and lowest distensibility were found in the preterm-AGA group. Height-adjusted systolic blood pressure was higher in the preterm groups than in the term-AGA group (p = 0.018). Cardiac function and size did not differ between the groups.

CONCLUSION

IUGR and preterm birth appear to be associated with structural changes in the arterial wall, whereas preterm birth seems to be associated with higher blood pressure. Using conventional echocardiography, we observed no effect of IUGR on cardiac size and function.

Preterm birth and the metabolic syndrome in adult life: a systematic review and meta-analysis

BACKGROUND

Preterm birth is associated with features of the metabolic syndrome in later life. We performed a systematic review and meta-analysis of studies reporting markers of the metabolic syndrome in adults born preterm.

METHODS

Reports of metabolic syndrome-associated features in adults (≥18 years of age) born at <37-week gestational age and at term (37- to 42-week gestational age) were included. Outcomes assessed were BMI, waist-hip ratio, percentage fat mass, systolic (SBP) and diastolic (DBP) blood pressure, 24-hour ambulatory SBP and DBP, flow-mediated dilatation, intima-media thickness, and fasting glucose, insulin, and lipid profiles.

RESULTS

Twenty-seven studies, comprising a combined total of 17,030 preterm and 295,261 term-born adults, were included. In adults, preterm birth was associated with significantly higher SBP (mean difference, 4.2 mm Hg; 95% confidence interval [CI], 2.8 to 5.7; P < .001), DBP (mean difference, 2.6 mm Hg; 95% CI, 1.2 to 4.0; P < .001), 24-hour ambulatory SBP (mean difference, 3.1 mm Hg; 95% CI, 0.3 to 6.0; P = .03), and low-density lipoprotein (mean difference, 0.14 mmol/L; 95% CI, 0.05 to 0.21; P = .01). The preterm-term differences for women was greater than the preterm-term difference in men by 2.9 mm Hg for SBP (95% CI [1.1 to 4.6], P = .004) and 1.6 mm Hg for DBP (95% CI [0.3 to 2.9], P = .02).

CONCLUSIONS

For the majority of outcome measures associated with the metabolic syndrome, we found no difference between preterm and term-born adults. Increased plasma low-density lipoprotein in young adults born preterm may represent a greater risk for atherosclerosis and cardiovascular disease in later life. Preterm birth is associated with higher blood pressure in adult life, with women appearing to be at greater risk than men.

Aortic wall thickness and amniotic fluid albuminuria in growth-restricted twin fetuses

BACKGROUND AND OBJECTIVE

Intrauterine growth restriction (IUGR) may be associated with significantly higher aortic intima-media thickening (aIMT) values. It is unknown if fetal aIMT is associated with glomerulosclerosis and amniotic albuminuria in utero.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Fetal abdominal aIMT and amniotic albumin/creatinine ratio (ACR) were measured in 126 individual twin fetuses, recruited by the Obstetrics and Gynaecology Clinics of the University of Padua (Italy) Medical Center. The IUGR twin fetuses were classified into two groups: Group A were those fetuses whose estimated fetal weight (EFW) was <10th percentile with pulsatility index >2 SD and Group B were those fetuses whose EFW was <10th percentile and had no velocimetry abnormalities.

RESULTS

The median fetal aIMT was significantly different in the three groups (Group A = 0.9 mm; Group B = 0.7 mm; and appropriate for gestational age (AGA) = 0.5 mm; p < .0001). It was significantly higher in Group A than in the AGA group (p < .0001) and than in the Group B fetuses (p = .003), respectively. In addition, ACR was different in the three groups (Group A = 183,500 mg/g; Group B = 6,4720 mg/g; and AGA = 8,2750 mg/g; p = .0002). It was significantly higher in Group A than in the AGA group (p = .03) and than in Group B (p = .02), respectively.

CONCLUSIONS

Growth-restricted twin fetuses with velocimetry abnormalities present are associated with aIMT and higher ACR levels in amniotic fluid, which could be possible markers in utero of preclinical atherosclerosis, and early glomerulosclerosis.

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.

Cardiovascular function in adulthood following intrauterine growth restriction with abnormal fetal blood flow

OBJECTIVES

To examine whether intrauterine growth restriction (IUGR) is associated with increased cardiovascular risk later in life.

METHODS

We examined 19 young adults (aged 22-25 years) who were born at term after IUGR, along with 18 controls. All had been examined previously with fetal Doppler, and in the present follow-up with echocardiography, carotid echo-tracking ultrasound, applanation tonometry, blood pressure and laser Doppler, in order to characterize their cardiac and vascular geometry and/or function.

RESULTS

The diameter of the ascending aorta and the left ventricular diameter were smaller in the IUGR group, but only ascending aortic diameter remained significantly smaller after adjustment for body surface area (P < 0.05). The aortic pressure augmentation index was higher in the IUGR group (P < 0.05). The common carotid artery diameter, intima-media thickness and distensibility as well as left ventricular mass and function were similar in the two groups. IUGR status was found to be an independent predictor of ascending aortic diameter.

CONCLUSIONS

IUGR due to placental dysfunction seems to contribute to the higher systolic blood pressure augmentation and the smaller aortic dimensions that are observed in adults more than 20 years later, with possible negative consequences for future left ventricular performance due to increased aortic impedance.

Developmental programming of cardiovascular risk in intrauterine growth-restricted twin fetuses according to aortic intima thickness

OBJECTIVES

We aimed to test the hypothesis that aortic intima thickness is greater in intrauterine growth-restricted (IUGR) twin fetuses compared to normally developing twins, thus defining an increased cardiovascular risk that reflects genetic factors in fetuses sharing the same womb.

METHODS

We conducted a prospective study performed on twins from January 2009 to July 2011. Twins were classified into 3 groups: IUGR fetuses with an estimated fetal weight below the 10th percentile and an umbilical artery pulsatility index of greater than 2 SDs (group A), fetuses with an estimated fetal weight below the 10th percentile and normal Doppler findings (group B), and fetuses with an estimated fetal weight appropriate for gestational age (group C). Aortic intima thickness was measured at a median gestational age of 32 weeks. Values were compared among groups and between each twin and cotwin, also considering sex and chorionicity.

RESULTS

Twenty-five fetuses were classified as group A, 36 as group B, and 95 as group C. The median aortic intima thickness values were 0.9 mm in group A, 0.7 mm in group B, and 0.6 mm in group C (P < .0001). There was a statistically significant difference between the aortic intima thickness of the twins and cotwins in groups A and B (P < .0001). Sex and chorionicity did not correlate with aortic intima thickness.

CONCLUSIONS

In this study, IUGR fetuses with Doppler abnormalities had greater aortic intima thickness, and IUGR twins with normal Doppler findings had intermediate thickness, supporting a genetic predisposition to cardiovascular risk independent of sex and chorionicity.

Fetal aortic wall thickness: a marker of hypertension in IUGR children?

Fetuses with intrauterine growth restriction (IUGR) have significant aortic intima-media thickening (aIMT), which suggests that preclinical atherosclerosis might predispose the infants to hypertension. However, the natural course of aIMT in babies with IUGR remains an open question.The study enrolled 77 pregnant women between January 2007 and August 2009. The fetuses were classified as AGA (appropriate for gestational age) or IUGR, if the estimated fetal weight was between the 10th and 90th percentile or below the 10th percentile (with umbilical artery pulsatility index (PI) >2s.d.), respectively. Anthropometric parameters and aIMT were detected in each IUGR and AGA fetus at a mean gestational age of 32 weeks. The follow-up was performed in 25 IUGR and 25 AGA infants at a mean postnatal age of 18 months; the previous measurements were repeated, and blood pressure measurements were taken. The maximum aIMT was significantly higher in the IUGR fetuses and infants compared with the AGA infants, both in utero (2.05±0.43 vs. 1.05±0.19 mm, P<0.001) and at the follow-up (2.3±0.8 vs. 1.06±0.18 mm, P<0.0001), the resulting values significantly correlated (P=0.018) with one another. The systolic blood pressure was significantly increased in the IUGR subjects (123±16 vs. 104±8.5 mm Hg, P<0.0004), and it correlated with the prenatal and postnatal aIMT values (P<0.0156 and P<0.0054, respectively). The aortic wall thickening progression in IUGR fetuses and infants differed from AGA, which may predispose the infants to hypertension early in life and cardiovascular risk later in life.

Renal function and systolic blood pressure in very-low-birth-weight infants 1-3 years of age

BACKGROUND

Preterm very-low-birth-weight (PT-VLBW) infants are at risk of an elevated systolic blood pressure (SBP) in infancy and adulthood; however, the pathogenesis remains unclear. Altered renal development or function may be associated with increased SBP, but their contribution in PT-VLBW is unknown.

METHODS

We determined renal function and its relationship to SBP in three groups of PT-VLBW at 1, 2, and 3 years of age, using serum cystatin-C to calculate the estimated glomerular filtration rate (eGFR).

RESULTS

Cystatin-C levels decreased from 0.84 ± 0.2 (SD) within the 1-year group to 0.70 ± 0.1 mg/l (±SD; P < 0.001) at 3 years and were unrelated to gender, fetal growth, and neonatal indomethacin exposure. eGFR rose from 121 ± 59 in the 1-year group to 138 ± 21 ml/min · 1.73 m(2) (P < 0.001) at 3 years. At 1 year, cystatin-C levels decreased with increasing SBP (P < 0.007), and infants with SBP ≥ 90 th% had lower cystatin-C and higher eGFR (P < 0.05). At 3 years, infants with lower birth weight (P < 0.03) and gestational age (P = 0.06) had reduced eGFR.

CONCLUSIONS

Preterm very-low-birth-weight infants demonstrate increasing renal function with advancing age. An elevated SBP and eGFR at 1 year suggests dysfunctional renal autoregulation and hyperfiltration, which may alter subsequent renal function and contribute to the lower eGFR seen at 3 years in infants with the lowest birth weight and gestational age.

Predicting later-life outcomes of early-life exposures

BACKGROUND

In utero exposure of the fetus to a stressor can lead to disease in later life. Epigenetic mechanisms are likely mediators of later-life expression of early-life events.

OBJECTIVES

We examined the current state of understanding of later-life diseases resulting from early-life exposures in order to identify in utero and postnatal indicators of later-life diseases, develop an agenda for future research, and consider the risk assessment implications of this emerging knowledge.

METHODS

This review was developed based on our participation in a National Research Council workshop titled "Use of in Utero and Postnatal Indicators to Predict Health Outcomes Later in Life: State of the Science and Research Recommendations." We used a case study approach to highlight the later-life consequences of early-life malnutrition and arsenic exposure.

DISCUSSION

The environmental sensitivity of the epigenome is viewed as an adaptive mechanism by which the developing organism adjusts its metabolic and homeostatic systems to suit the anticipated extrauterine environment. Inappropriate adaptation may produce a mismatch resulting in subsequent increased susceptibility to disease. A nutritional mismatch between the prenatal and postnatal environments, or early-life obesogen exposure, may explain at least some of the recent rapid increases in the rates of obesity, type 2 diabetes, and cardiovascular diseases. Early-life arsenic exposure is also associated with later-life diseases, including cardiovascular disease and cancer.

CONCLUSIONS

With mounting evidence connecting early-life exposures and later-life disease, new strategies are needed to incorporate this emerging knowledge into health protective practices.

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.

Increased urinary podocytes following indomethacin suggests drug-induced glomerular injury

BACKGROUND

Preterm infants are delivered while glomerulogenesis is ongoing and may be exposed to insults, including medications that may affect renal development. Podocytes detected in the urine are an indicator of glomerular injury. The aims of this study were to determine whether preterm and term infants excrete podocytes in their urine and whether exposure to gentamicin and indomethacin increase podocyte excretion in their urine.

METHODS

Preterm infants <33 weeks gestation had urine collected each day while receiving either gentamicin or indomethacin. Preterm and term control infants had urine collected for 3 days. The number of casts and podocytes present in the urine of infants receiving indomethacin and gentamicin were compared with preterm and term control infants.

RESULTS

Forty-two neonates were included in the study. Podocytes were present in small numbers (< 2) in the urine of both preterm and term control neonates. The number of podocytes in the preterm group receiving indomethacin was significantly higher than in all other groups (p=0.02) ,as was urinary albumin (p=0.02).

CONCLUSIONS

Increased number of podocytes in preterm neonates receiving indomethacin and higher excretion of albumin suggest glomerular injury is occurring. It is unknown whether injury to glomeruli during glomerulogenesis in preterm neonates has long-term sequelae for renal development and function into adulthood.

Twinship influence on morbidity and mortality across the lifespan

BACKGROUND

Studies in twins may be questioned with respect to their representativeness of the general population, not least considering the potential importance of the fetal environment for future health and disease. To better understand the influence twinning may have on health, we investigated long-term health outcomes of twins, their singleton siblings and singletons from the population.

METHODS

Morbidity and mortality in twins was contrasted to that of their singleton siblings. These singletons from families with twins were then compared with singletons of the population to further reveal potential twin family influences on health. Familial relations were identified through the Swedish Multi-Generation Register. Among individuals born between 1932 and 1958, the number of twins and their singleton siblings identified were 49,156 and 35,277, respectively. Outcomes were incident overall cancer, cardiovascular disease (CVD) and death, identified in national registers. Standardized survival functions were estimated using Cox proportional hazards regression and the corresponding cumulative risks plotted against age.

RESULTS

Cumulative risks of cancer, CVD and death in twins did not differ from singletons of families with twins, who in turn were found to be similar to singletons of families without twins. As could be expected from these findings, no differences in risks were found when twins were compared with singletons of the population.

CONCLUSIONS

Despite their adverse intrauterine experience, twins do not seem to fare worse than singletons with respect to adult morbidity and mortality. The findings indicate that the unique experience of twinning does not lead to adverse long-term health outcomes.

High blood pressure in 2.5-year-old children born extremely preterm

OBJECTIVE

Adolescents and young adults born preterm have elevated blood pressure (BP). The objective of this study was to investigate if BP is elevated at 2.5 years of age after an extremely preterm birth (EXPT).

METHODS

In a regional subset of the national population-based cohort Extremely Preterm Infants in Sweden Study, BP at 2.5 years of age was studied in 68 survivors of EXPT (gestational age: 23.6-26.9 weeks; mean ± SD birth weight: 810 ± 164 g), and 65 matched controls born at term.

RESULTS

At follow-up at 2.5 years of corrected age, EXPT children had significantly higher systolic blood pressure (SBP) and diastolic blood pressure (DBP) z scores than controls born at term, according to pediatric BP nomograms by age, gender, and height. The proportion of SBP ≥90th percentile was 44% (30 of 68) in EXPT children and 23% (15 of 65) in controls (P = .01). In logistic regression analyses stratified according to gender, EXPT was associated with an odds ratio for a SBP ≥90th percentile of 3.32 (95% confidence interval: 1.25-8.81) among boys. The corresponding odds ratio among EXPT girls was 2.18 (95% confidence interval: 0.62-7.61). In EXPT children, SBP and DBP z scores were inversely correlated to catch-up growth from 36 weeks' postmenstrual age to follow-up at 2.5 years of age.

CONCLUSIONS

Children born extremely preterm have elevated office SBP and DBP at a corrected age of 2.5 years. This finding might have implications for their cardiovascular health later in life.

[In utero fetal programming and its impact on health in adulthood]

Adverse events during intrauterine life may program organ growth and favor disease later in life. This is the usually called 'Barker's hypothesis'. Increasing evidence suggests that conditions like vascular disease, hypertension, metabolic syndrome, and type 2 diabetes mellitus are programmed during the early stages of fetal development and become manifest in late stages of life, when there is an added impact of lifestyle and other conventional acquired environmental risk factors that interact with genetic factors. The aim of this review was to provide additional, updated evidence to support the association between intrauterine fetal health and increased prevalence of chronic non-communicable diseases in adulthood. Various potential cellular and molecular mechanisms proposed to be related to the above hypothesis are discussed, including endothelial function, oxidative stress, insulin resistance, and mitochondrial function.

Preterm birth with antenatal corticosteroid administration has injurious and persistent effects on the structure and composition of the aorta and pulmonary artery

INTRODUCTION

Preterm birth affects 8-12% of live births and is associated with the development of elevated arterial blood pressure and aortic narrowing in later life; this suggests that preterm birth may alter the development of arteries. Our objective was to determine the effects of preterm birth, accompanied by antenatal corticosteroid administration, on the structure of the aorta and pulmonary artery, which experience different alterations in pressure flow at birth.

RESULTS

At 11 wk, preterm lambs had significantly thicker aortic walls and a smaller lumen, whereas the morphometry of the pulmonary artery was unaffected. Elastin deposition was markedly increased in the aorta and pulmonary artery and smooth muscle content was reduced in the aorta only. In preterm lambs we found injury in the aorta only; controls were unaffected.

DISCUSSION

We conclude that moderate preterm birth after antenatal betamethasone can cause injury and persistent alterations in the structure and composition of the aorta, with lesser effects in the pulmonary artery. Our findings suggest that preterm birth may increase the risk of atherosclerosis and aortic aneurysms in later life.

METHODS

Using an established ovine model of preterm birth, lambs were born at 0.9 of gestation and underwent necropsy at 11 wk after birth; controls were born at term.

Systematic review and meta-analysis of preterm birth and later systolic blood pressure

Lower birth weight because of fetal growth restriction is associated with higher blood pressure later in life, but the extent to which preterm birth (<37 completed weeks' gestation) or very low birth weight (<1500 g) predicts higher blood pressure is less clear. We performed a systematic review of 27 observational studies that compared the resting or ambulatory systolic blood pressure or diagnosis of hypertension among children, adolescents, and adults born preterm or very low birth weight with those born at term. We performed a meta-analysis with the subset of 10 studies that reported the resting systolic blood pressure difference in millimeters of mercury with 95% CIs or SEs. We assessed methodologic quality with a modified Newcastle-Ottawa Scale. The 10 studies were composed of 1342 preterm or very low birth weight and 1738 term participants from 8 countries. The mean gestational age at birth of the preterm participants was 30.2 weeks (range: 28.8-34.1 weeks), birth weight was 1280 g (range: 1098-1958 g), and age at systolic blood pressure measurement was 17.8 years (range: 6.3-22.4 years). Former preterm or very low birth weight infants had higher systolic blood pressure than term infants (pooled estimate: 2.5 mm Hg [95% CI: 1.7-3.3 mm Hg]). For the 5 highest quality studies, the systolic blood pressure difference was slightly greater, at 3.8 mm Hg (95% CI: 2.6-5.0 mm Hg). We conclude that infants who are born preterm or very low birth weight have modestly higher systolic blood pressure later in life and may be at increased risk for developing hypertension and its sequelae.