Associations of gestational age and intrauterine growth with systolic blood pressure in a family-based study of 386,485 men in 331,089 families

Cardiometabolic health in adults born with very low birth weight-a sibling study

BACKGROUND

Preterm survivors have increased risk for impaired cardiometabolic health. We assessed glucose regulation and cardiometabolic biomarkers in adult very low birth weight (VLBW, <1500 g) survivors, using siblings as controls.

METHODS

VLBW-participants were matched with term-born, same-sex siblings. At mean age 29.2 years (SD 3.9), 74 VLBW-adults and 70 siblings underwent a 2-h 75 g oral glucose tolerance test and blood tests for assessment of cardiometabolic biomarkers.

RESULTS

Of participants, 23 (31%) VLBW and 11 (16%) sibling-controls met World Health Organization criteria for impaired glucose regulation (OR adjusted for age and sex 2.5, 95% CI: 1.1 to 5.8). Adjusting for age and sex, VLBW-participants showed 9.2% higher 2-h glucose (95% CI: 0.4% to 18.8%) than their siblings. Also, fasting (13.4%, -0.3% to 29.0%) and 2-h free fatty acids (15.6%, -2.4% to 36.9%) were higher in VLBW-participants. These differences were statistically significant only after further adjusting for confounders. No statistically significant differences were found regarding other measured biomarkers, including insulin resistance, atherogenic lipid profiles or liver tests.

CONCLUSIONS

VLBW-adults showed more impaired fatty acid metabolism and glucose regulation. Differences in cardiometabolic biomarkers were smaller than in previous non-sibling studies. This may partly be explained by shared familial, genetic, or environmental factors.

IMPACT

At young adult age, odds for impaired glucose regulation were 3.4-fold in those born at very low birth weight, compared to same-sex term-born siblings. Taking into consideration possible unmeasured, shared familial confounders, we compared cardiometabolic markers in adults born preterm at very low birth weight with term-born siblings. Prematurity increased risk for impaired glucose regulation, unrelated to current participant characteristics, including body mass index. In contrast to previous studies, differences in insulin resistance were not apparent, suggesting that insulin resistance may partially be explained by factors shared between siblings. Also, common cardiometabolic biomarkers were similar within sibling pairs.

The association of gestational age and birthweight with blood pressure, cardiac structure, and function in 4 years old: a prospective birth cohort study

BACKGROUND

Current evidence relating birthweight and gestational age to cardiovascular risk is conflicting. Whether these factors have independent or interactive impacts on cardiovascular parameters during early childhood remains unclear. The goal of this study was to explore whether there were any independent and interactive effects of gestational age and birthweight on blood pressure, left ventricle (LV) structure, and function in 4 years old.

METHODS

This study included 1194 children in the Shanghai Birth Cohort from 2013 to 2016. Information about the mothers and children was recorded at time of birth using a questionnaire. Follow-up measurements, including anthropometric, blood pressure, and echocardiography, were taken between 2018 and 2021, when the children were 4 years old. Multiple linear or logistic regressions and restricted cubic spline were used to explore the association of birthweight and gestational age with cardiovascular measurements.

RESULTS

Gestational age had a significant negative correlation with both systolic blood pressure [β =  - 0.41, 95% CI: (- 0.76, - 0.07)] and mean arterial pressure [β =  - 0.36, 95%CI: (- 0.66, - 0.07)]. The risk of prehypertension decreased with increased gestational age [OR = 0.54, 95% CI: (0.32, 0.93)]. The relationship between birthweight with blood pressure was U-shape (P for non-linear < 0.001). The wall thickness, volume, mass, and cardiac output of LV increased with birthweight, though the ejection fraction [β =  - 1.02, 95% CI: (- 1.76, - 0.27)] and shorten fraction [β = 0.72, 95% CI: (- 1.31, - 0.14)] decreased with birthweight. The risk of LV hypertrophy was not associated with birthweight [OR = 1.59, 95% CI: (0.68, 3.73)].

CONCLUSIONS

In this study, we found different associations of birthweight and gestational age with cardiovascular measurements in the offspring at 4 years old. Gestational age influenced blood pressure independent of birthweight. Heart size and function at 4 years old was influenced mostly by birthweight and not by gestational age.

A. Sørensen T, Elhakeem A, Santos AC, Pinot de Moira A, Heude B, Iñiguez C, Pizzi C, Simons E, Voerman E, Corpeleijn E, Zariouh F, Santorelli G, Inskip HM, Barros H, Carson J, Harris JR, Nader JL, Ronkainen J, Strandberg-Larsen K, Santa-Marina L, Calas L, Cederkvist L, Popovic M, Charles MA, Welten M, Vrijheid M, Azad M, Subbarao P, Burton P, Mandhane PJ, Huang RC, Wilson RC, Haakma S, Fernández-Barrés S, Turvey S, Santos S, Tough SC, Sebert S, Moraes TJ, Salika T, Jaddoe VWV, Lawlor DA, Nybo Andersen AM. Gestational age at birth and body size from infancy through adolescence: An individual participant data meta-analysis on 253,810 singletons in 16 birth cohort studies

BACKGROUND

Preterm birth is the leading cause of perinatal morbidity and mortality and is associated with adverse developmental and long-term health outcomes, including several cardiometabolic risk factors and outcomes. However, evidence about the association of preterm birth with later body size derives mainly from studies using birth weight as a proxy of prematurity rather than an actual length of gestation. We investigated the association of gestational age (GA) at birth with body size from infancy through adolescence.

METHODS AND FINDINGS

We conducted a two-stage individual participant data (IPD) meta-analysis using data from 253,810 mother-child dyads from 16 general population-based cohort studies in Europe (Denmark, Finland, France, Italy, Norway, Portugal, Spain, the Netherlands, United Kingdom), North America (Canada), and Australasia (Australia) to estimate the association of GA with body mass index (BMI) and overweight (including obesity) adjusted for the following maternal characteristics as potential confounders: education, height, prepregnancy BMI, ethnic background, parity, smoking during pregnancy, age at child's birth, gestational diabetes and hypertension, and preeclampsia. Pregnancy and birth cohort studies from the LifeCycle and the EUCAN-Connect projects were invited and were eligible for inclusion if they had information on GA and minimum one measurement of BMI between infancy and adolescence. Using a federated analytical tool (DataSHIELD), we fitted linear and logistic regression models in each cohort separately with a complete-case approach and combined the regression estimates and standard errors through random-effects study-level meta-analysis providing an overall effect estimate at early infancy (>0.0 to 0.5 years), late infancy (>0.5 to 2.0 years), early childhood (>2.0 to 5.0 years), mid-childhood (>5.0 to 9.0 years), late childhood (>9.0 to 14.0 years), and adolescence (>14.0 to 19.0 years). GA was positively associated with BMI in the first decade of life, with the greatest increase in mean BMI z-score during early infancy (0.02, 95% confidence interval (CI): 0.00; 0.05, p < 0.05) per week of increase in GA, while in adolescence, preterm individuals reached similar levels of BMI (0.00, 95% CI: -0.01; 0.01, p 0.9) as term counterparts. The association between GA and overweight revealed a similar pattern of association with an increase in odds ratio (OR) of overweight from late infancy through mid-childhood (OR 1.01 to 1.02) per week increase in GA. By adolescence, however, GA was slightly negatively associated with the risk of overweight (OR 0.98 [95% CI: 0.97; 1.00], p 0.1) per week of increase in GA. Although based on only four cohorts (n = 32,089) that reached the age of adolescence, data suggest that individuals born very preterm may be at increased odds of overweight (OR 1.46 [95% CI: 1.03; 2.08], p < 0.05) compared with term counterparts. Findings were consistent across cohorts and sensitivity analyses despite considerable heterogeneity in cohort characteristics. However, residual confounding may be a limitation in this study, while findings may be less generalisable to settings in low- and middle-income countries.

CONCLUSIONS

This study based on data from infancy through adolescence from 16 cohort studies found that GA may be important for body size in infancy, but the strength of association attenuates consistently with age. By adolescence, preterm individuals have on average a similar mean BMI to peers born at term.

Associations of maternal and fetal vitamin D status with childhood body composition and cardiovascular risk factors

Maternal vitamin D deficiency during pregnancy may have persistent adverse effects on childhood growth and development. We examined whether 25-hydroxyvitamin D (25(OH)D) concentrations during pregnancy and at cord blood were associated with childhood body composition and cardiovascular outcomes. This study was embedded in a population-based prospective cohort in Rotterdam, The Netherlands, among 4,903 mothers and their offspring. We measured 25(OH)D concentrations at a median gestational age of 20.4 weeks (95% range 18.5-23.4 weeks) and at birth (40.1 weeks [95% range 35.8-42.3 weeks]). 25(OH)D concentrations were categorized into severely deficient (<25.0 nmol/L); deficient (25.0 to 49.9 nmol/L); sufficient (50.0 to 74.9 nmol/L) and optimal (≥75.0 nmol/L). At 6 years, we measured childhood body mass index; fat and lean mass by Dual-energy X-ray Absorptiometry; blood pressure; and serum cholesterol, triglycerides, and insulin concentrations. Compared with children from mothers with optimal 25(OH)D concentrations (≥75.0 nmol/L), those of severely deficient vitamin D (<25.0 nmol/L) mothers had a 0.12 standard deviation score (SDS); (95% Confidence Interval (CI) [0.03, 0.21]) higher fat mass percentage and a 0.13 SDS (95% CI [-0.22, -0.04]) lower lean mass percentage. These associations remained after adjustment for current child vitamin D status. Maternal and cord blood 25(OH)D concentrations were not associated with cardiovascular risk factors in childhood. In conclusion, severe maternal 25(OH)D deficiency (<25.0 nmol/L) during pregnancy is associated with an adverse childhood body composition profile, but we did not observe evidence for an association with childhood cardiovascular risk factors. Further studies are needed to replicate our findings, to examine the underlying mechanisms, the causality of the associations, and the potential for public health interventions.

Stereological study of developing glomerular forms during human fetal kidney development

BACKGROUND

Human fetal kidney development is a complex and stepwise process. The number, shape, size and distribution of glomeruli provide important information on kidney organization. The aim of this study was to quantify glomerular developing forms during human fetal kidney development using stereological methods.

METHODS

Kidney tissue specimens of 40 human fetuses with gestational ages ranging from 9 to 40 weeks were analyzed. Specimens were divided into eight groups based on gestational age, each corresponding to 1 lunar month. Stereological methods were used at the light microscopy level to estimate volume, surface and numerical density of the glomerular developing forms.

RESULTS

During gestation, nephrogenesis continually advanced, and the number of nephrons increased. Volume, surface and numerical densities of vesicular forms and S-shaped bodies decreased gradually in parallel with gradual increases in estimated stereological parameters for vascularized glomeruli. Volume density and surface density of vascularized glomeruli increased gradually during fetal kidney development, and numerical density increased until the seventh lunar month. A relative decrease in vascularized glomeruli per unit volume of cortex occurred during the last 3 lunar months. Nephrogenesis began to taper off by 32 weeks and was completed by 36 weeks of gestation. The last sample in which we observed vesicles was from a fetus aged 32 weeks, and the last sample with S-shaped bodies was from a fetus aged 36 weeks.

CONCLUSIONS

The present study is one of few quantitative studies conducted on human kidney development. Knowledge of normal human kidney morphogenesis during development could be important for future medical practice. Events occurring during fetal life may have significant consequences later in life.

Parental pre-pregnancy BMI influences on offspring BMI and waist circumference at 21 years

OBJECTIVES

To investigate the prospective association between parental pre-pregnancy BMI and adult male and female offspring BMI and waist circumference (WC).

METHODS

Sub-sample of 2,229 parent-offspring pairs with parental pre-pregnancy BMI and offspring BMI and WC at 21 years were used from the MUSP (Mater-University of Queensland Study of Pregnancy cohort). Multivariable results were adjusted for maternal factors around pregnancy (e.g. gestational weight and smoking during pregnancy) and offspring factors in early life (e.g. birth weight) and at 14 years (e.g. sports participation and mealtime with family).

RESULTS

After adjustments for confounders, each unit increase in paternal and maternal BMI, the BMI of young adult offspring increased by 0.33kg/m² and 0.35kg/m² , and the WC increased by 0.76 cm and 0.62 cm, respectively. In the combination of parents' weight status, offspring at 21 years were six times the risk being overweight/obese (OW/OB) when both parents were OW/OB, compared to offspring of healthy weight parents.

CONCLUSIONS

Prenatal parental BMI are independently related to adult offspring BMI and WC.

IMPLICATIONS

Both prenatal paternal-maternal weight status are important determinants of offspring weight status in long-term. Further studies are warranted to investigate the underlying mechanisms.

A lower reduction in umbilical artery pulsatility in mid-pregnancy predicts higher infant blood pressure six months after birth

AIM

The Norwegian-based Cardiovascular Risk Reduction Diet in Pregnancy study found that a cholesterol-lowering diet during pregnancy was associated with an accentuated reduction in the umbilical artery pulsatility index. This follow-up study assessed the possible association between the index and the infants' blood pressure at six months of age.

METHODS

In the original study, pregnant women consumed an anti-atherogenic or usual diet from gestational weeks 17-20 to birth and underwent Doppler velocimetry at 24, 30 and 36 gestational weeks. In this follow-up study, blood pressure was measured in 105 mother-infant pairs in the intervention group and 106 mother-infant pairs in the control group six months after birth.

RESULTS

Mean systolic and diastolic blood pressures were not significantly different between both groups. When the groups were combined, multivariate linear analyses showed that a lower versus higher reduction (≥-0.17 versus <-0.17) in the umbilical artery pulsatility index between gestational weeks 24 and 30 and maternal diastolic blood pressure at six months postpartum were significant predictors of higher infant systolic blood pressure (p = 0.03, 0.01, respectively).

CONCLUSION

A lower reduction in umbilical pulsatility index in mid-pregnancy was associated with higher infant blood pressure at six months of age. This suggests that fetoplacental intrauterine factors may influence future cardiovascular risk.

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.

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.

Associations of maternal 25-hydroxyvitamin D in pregnancy with offspring cardiovascular risk factors in childhood and adolescence: findings from the Avon Longitudinal Study of Parents and Children

Objective

Lower maternal vitamin D status in pregnancy may be associated with increased offspring cardiovascular risk in later life, but evidence for this is scant. We examined associations of maternal total 25-hydroxyvitamin D (25(OH)D) in pregnancy with offspring cardiovascular risk factors assessed in childhood and adolescence.

Design

A longitudinal, prospective study.

Setting

The study was based on data from mother–offspring pairs in the Avon Longitudinal Study of Parents and Children (ALSPAC), a UK prospective population-based birth cohort (N=4109).

Outcome measures

Offspring cardiovascular risk factors were measured in childhood (mean age 9.9 years) and in adolescence (mean age 15.4 years): blood pressure, lipids, apolipoproteins (at 9.9 years only), glucose and insulin (at 15.4 years only), C reactive protein (CRP), and interleukin 6 (at 9.9 years only) were measured.

Results

After adjustments for potential confounders (maternal age, education, body mass index (BMI), smoking, physical activity, parity, socioeconomic position, ethnicity, and offspring gestational age at 25(OH)D sampling; gender, age, and BMI at outcome assessment), maternal 25(OH)D was inversely associated with systolic blood pressure (−0.48 mm Hg difference per 50 nmol/L increase in 25(OH)D; 95% CI −0.95 to −0.01), Apo-B (−0.01 mg/dL difference; 95% CI −0.02 to −0.001), and CRP (−6.1% difference; 95% CI −11.5% to −0.3%) at age 9.9 years. These associations were not present for risk factors measured at 15.4 years, with the exception of a weak inverse association with CRP (−5.5% difference; 95% CI −11.4% to 0.8%). There was no strong evidence of associations with offspring triglycerides, glucose or insulin.

Conclusions

Our findings suggest that fetal exposure to 25(OH)D is unlikely to influence cardiovascular risk factors of individuals later in life.

Second trimester estimated fetal weight and fetal weight gain predict childhood obesity

OBJECTIVE

To determine the extent to which fetal weight during mid-pregnancy and fetal weight gain from mid-pregnancy to birth predict adiposity and blood pressure (BP) at age 3 years.

STUDY DESIGN

Among 438 children in the Project Viva cohort, we estimated fetal weight at 16-20 (median 18) weeks' gestation using ultrasound biometry measures. We analyzed fetal weight gain as change in quartile of weight from the second trimester until birth, and we measured height, weight, subscapular and triceps skinfold thicknesses, and BP at age 3.

RESULTS

Mean (SD) estimated weight at 16-20 weeks was 234 (30) g and birth weight was 3518 (420) g. In adjusted models, weight estimated during the second trimester and at birth were associated with higher body mass index (BMI) z-scores at age 3 years (0.32 unit [95% CI, 0.04-0.60 unit] and 0.53 unit [95% CI, 0.24-0.81 unit] for the highest vs lowest quartile of weight). Infants with more rapid fetal weight gain and those who remained large from mid-pregnancy to birth had higher BMI z-scores (0.85 unit [95% CI, 0.30-1.39 unit] and 0.63 unit [95% CI, 0.17-1.09 unit], respectively) at age 3 than did infants who remained small during fetal life. We did not find associations between our main predictors and sum or ratio of subscapular and triceps skinfold thicknesses or systolic BP.

CONCLUSION

More rapid fetal weight gain and persistently high fetal weight during the second half of gestation predicted higher BMI z-score at age 3 years. The rate of fetal weight gain throughout pregnancy may be important for future risk of adiposity in childhood.

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.

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.

Fetal, developmental, and parental influences on cystatin C in childhood: the Uppsala Family Study

BACKGROUND

The aim was to identify determinants (biomedical and social characteristics of children and their parents) of cystatin C levels in healthy children drawn from a population sample.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

425 pairs of consecutive full siblings born 1987-1995 in Uppsala were identified using the Swedish Medical Birth Registry and invited with their parents for examination in 2000-2001.

OUTCOME

Serum cystatin C level was log-transformed and analyzed using random-effects models.

MEASUREMENTS

The examination in parents and children consisted of a nonfasting blood sample, anthropometry, and questionnaires about lifestyle and socioeconomic position. Tanner stage was used for assessment of pubertal status.

RESULTS

In age-, height-, and body mass index-adjusted analyses, cystatin C level increased by 2.6% (95% CI, 0.3%-4.8%) higher in Tanner stage 2 vs 1 girls, and 1.6% (95%CI, 0.2%-3.1%) lower in boys than girls. For every 10% increase in maternal cystatin C level, offspring cystatin C level increased by 3.0% (95% CI, 2.2%-3.8%); the equivalent effect for paternal cystatin C level was 2.1% (95% CI, 1.3%-2.9%). Lower maternal education was associated with a 2.4% (95% CI, 0.3%-4.6%) higher cystatin C level in their offspring.

LIMITATIONS

Cross-sectional study design, missing cystatin C values for subset of parents, lack of urinary measurements, no gold-standard measurement of glomerular filtration rate.

CONCLUSIONS

There are intergenerational associations of cystatin C level in families in line with previous reports of heritability of kidney disease. Lower maternal education is associated with higher cystatin C levels in their children. Further studies of healthy children are needed to explore the biological mechanisms for these findings. If cystatin C is measured, these studies will need to record pubertal stages.

[Preterm birth as a risk factor for high blood pressure in children: a systematic review]

Epidemiological studies have suggested that arterial hypertension is a chronic disease that begins in childhood, and that prematurity (birth at less than 37 weeks' gestational age) is potentially associated with the development of hypertension in childhood and adulthood. Our objective was to identify the association between prematurity and high blood pressure in children, using a systematic literature review. Original articles related to the theme and published in English, Portuguese, or Spanish from 1998 to 2009 were selected from the MEDLINE, LILACS, and SciELO databases. We excluded articles without abstracts, review articles, and articles not related to prematurity and hypertension in childhood. Nine articles were located and analyzed: 5 case-control studies, 2 cross-sectional studies, and 2 cohort studies. The majority of the studies failed to show an association between prematurity and arterial hypertension in childhood. However, the influence of prematurity should not be ruled out, given the small number of studies on this theme and the diversity of methodological approaches in the literature.

Association of maternal diabetes mellitus in pregnancy with offspring adiposity into early adulthood: sibling study in a prospective cohort of 280,866 men from 248,293 families

BACKGROUND

Maternal diabetes mellitus in pregnancy results in greater offspring adiposity at birth. It is unclear whether it is associated with greater adiposity into adulthood, and if so, whether this is via intrauterine mechanisms or shared familial characteristics.

METHODS AND RESULTS

A record-linkage prospective cohort study of 280,866 singleton-born Swedish men from 248,293 families was used to explore the intrauterine effect of maternal diabetes mellitus on offspring body mass index (BMI) in early adulthood. Maternal diabetes mellitus during pregnancy was associated with greater mean BMI at age 18 in their sons. The difference in BMI was similar within brothers and between nonsiblings. BMI of men whose mothers had diabetes mellitus during their pregnancy was on average 0.94 kg/m² greater (95% confidence interval [CI], 0.35 to 1.52) than in their brothers born before their mother was diagnosed with diabetes, after adjustment for birth year, maternal age, parity and education, birth weight, gestational age, and age at assessment of BMI. Early-pregnancy BMI was positively associated with son's BMI between nonsiblings, but there was no association within brothers. Adjustment of the maternal diabetes-offspring BMI association for maternal BMI did not alter the association either within brothers or between nonsiblings. Results were also robust to sensitivity analyses restricting the within-sibling analyses to siblings born within 3 years of each other.

CONCLUSION

Maternal diabetes mellitus has long-term consequences for greater BMI in offspring; this association is likely to be via intrauterine mechanisms, and is independent of maternal BMI in early pregnancy.

Maternal smoking during pregnancy and kidney volume in the offspring: the Generation R Study

An adverse fetal environment leads to smaller kidneys, with fewer nephrons, which might predispose an individual to the development of kidney disease and hypertension in adult life. In a prospective cohort study among 1,072 children followed from early fetal life onward, we examined whether maternal smoking during pregnancy, as a significant adverse fetal exposure, is associated with fetal (third trimester of pregnancy, n = 1,031) and infant kidney volume (2 years of age, n = 538) measured by ultrasound. Analyses were adjusted for various potential confounders. Among mothers who continued smoking, we observed dose-dependent associations between the number of cigarettes smoked during pregnancy and kidney volume in fetal life. Smoking less than five cigarettes per day was associated with larger fetal combined kidney volume, while smoking more than ten cigarettes per day tended to be associated with smaller fetal combined kidney volume (p for trend: 0.002). This pattern was not significant for kidney volume at the age of 2 years. Our results suggest that smoking during pregnancy might affect kidney development in fetal life with a dose-dependent relationship. Further studies are needed to assess the underlying mechanisms and whether these differences in fetal kidney volume have postnatal consequences for kidney function and blood pressure.

Preeclampsia and gestational hypertension are associated with childhood blood pressure independently of family adiposity measures: the Avon Longitudinal Study of Parents and Children

BACKGROUND

Offspring of women with hypertensive disorders of pregnancy are at increased risk of cardiovascular complications later in life, but the mechanisms underlying these associations are unclear. Our aim was to examine whether adjusting for birth weight and familial adiposity changed the association of hypertensive disorders of pregnancy with offspring blood pressure.

METHODS AND RESULTS

Using data from 6343 nine-year-old participants in the Avon Longitudinal Study of Parents and Children, we examined the association between hypertensive disorders of pregnancy (preeclampsia and gestational hypertension) and offspring blood pressure. Both preeclampsia and gestational hypertension were associated with systolic and diastolic blood pressures in the 9-year-old offspring; after adjustment for parental and own adiposity and for other potential confounders, the mean difference in systolic blood pressure was 2.05 mm Hg (95 confidence interval, 0.72 to 3.38) and 2.04 mm Hg (95 confidence interval, 1.42 to 2.67) for preeclampsia and gestational hypertension, respectively, compared with those with no hypertensive disorders of pregnancy. Equivalent results for diastolic blood pressure were 1.00 mm Hg (95 confidence interval, -0.01 to 2.10) and 1.07 mm Hg (95 confidence interval, 0.60 to 1.54). The association of preeclampsia with offspring systolic and diastolic blood pressures attenuated toward the null with further adjustment for birth weight and gestational age, whereas these adjustments did not attenuate the association of gestational hypertension with offspring blood pressure.

CONCLUSIONS

The associations of hypertensive disorders of pregnancy with higher offspring blood pressure are not explained by familial adiposity. The mechanisms linking preeclampsia and gestational hypertension with offspring blood pressure may differ, with the former mediated at least in part by the effect of preeclampsia on intrauterine growth restriction.

Gestational age differences in health and development among young Swedish men born at term

BACKGROUND

Although increased morbidity and mortality associated with pre-term birth and restricted fetal growth have been extensively studied, relatively little is known about variations in health outcomes among term births, because they are often assumed to be homogeneous.

METHODS

We examined variations in height, body mass index (BMI), systolic and diastolic blood pressure (SBP and DBP), and intellectual performance by gestational age and fetal 'growth' (birth weight for gestational age) among young Swedish men born at term (37-41 weeks of gestation). We also compared the magnitude of associations among 314,642 men from different families and among 72,212 full brothers from 35,215 families to assess whether the associations are explained by familial factors shared by siblings.

RESULTS

Gestational age in completed weeks was positively associated with height [0.11 cm, 95% confidence interval (CI): 0.09-0.13] and intellectual performance (0.01, 95% CI: 0.00-0.02) and negatively associated with SBP (-0.28 mmHg, 95% CI: -0.33 to -0.24), after controlling for birth weight, maternal age at the men's birth, parity, family socio-economic position and family structure. The associations with height and SBP were observed also among brothers within families, suggesting that they are not explained by shared family characteristics. However, the positive association between gestational age and intellectual performance was no longer present within families. Birth weight for gestational age (z-score) was positively associated with height, BMI and intellectual performance and negatively associated with SBP. These associations were robust within families.

CONCLUSIONS

Among young men born at term, fetal growth and even gestational age are independently associated with adult size, BP and cognitive ability. The extent to which shared family characteristics explain the associations varies across outcomes.

Clinical and ultrasound work-up and follow-up of preeclampsia

Hypertensive disorders are frequent during pregnancy and are related with an important morbidity and mortality worldwide. In this review we aim to provide the reader with a comprehensive overview of the clinical aspects of and the diagnostic tools used in the primary assessment and the (long term) follow-up of preeclampsia. The focus in this review will lay on the clinical follow-up of both the mother and the fetus aiming at the prevention of severe maternal complications as well as preventing growth restriction and prematurity in the child.

Fetal environment and early age at natural menopause in a British birth cohort study

BACKGROUND

Early life development may influence the timing of natural menopause through association with size of the initial follicle pool or early follicular loss. This study examines the relationships of birthweight, gestational age and birthweight standardized by gestational age with early menopause in the 1958 British birth cohort study.

METHODS

Study participants were over 2900 women with data on birthweight, gestational age (obtained at birth), menopausal status at age 44-45 years and potential confounding factors. Logistic regression was used to study relationships of birthweight, gestational age and birthweight standardized by gestational age with post-menopausal status by 44-45 years, with and without adjustments for confounding factors.

RESULTS

There was a U-shaped association between birthweight and menopausal status at 44-45 years: women at either extremes of birthweight (<2.5 and >or=4.0 kg) had increased odds of post-menopausal status compared with those weighing 3.0-3.49 kg [odds ratio (OR) = 1.91, 95% confidence interval (CI) 1.08, 3.38; 1.81, 95% CI 1.11, 2.97, respectively]. Women with higher birthweight standardized by gestational age (which indicates faster fetal growth rate) also had increased odds of being post-menopausal by 44-45 years (OR for fastest quarter versus second fastest quarter = 1.80; 95% CI 1.16, 2.81). These associations persisted after adjustment for socioeconomic position at birth, adult smoking status and use of oral contraceptives.

CONCLUSIONS

These findings suggest that variations in fetal environment may be associated with the timing of menopause. Given that extremes of birthweight and higher birthweight standardized by gestational age were associated with earlier age at menopause, mechanisms related to these characteristics that also regulate ovarian function should be investigated further.

Challenges and novel approaches in the epidemiological study of early life influences on later disease

The influence of factors acting during early life on health outcomes of offspring is of considerable research and public health interest. There are, however, methodological challenges in establishing robust causal links, since exposures often act many decades before outcomes of interest, and may also be strongly related to other factors, generating considerable degrees of potential confounding. With respect to pre-natal factors, the degree of confounding can sometimes be estimated by comparing the association between exposures experienced by the mother during pregnancy and outcomes among the offspring with the association of the same exposures experienced by the father during the pregnancy period and offspring outcomes. If the effects are due to an intra-uterine exposure, then maternal exposure during pregnancy should have a clearly greater influence than paternal exposure. If confounding by socio-economic, behavioural or genetic factors generates the association then maternal and paternal pregnancy exposures will be related in the same way with the outcome. For early life exposures it is also possible to compare outcomes in siblings who are concordant or discordant for the exposure, which will reduce the influence of family-level confounding factors. A different approach is that of Mendelian randomization, which utilises genetic variants of known effect that can proxy for modifiable exposures and are also not in general related to potential confounding factors, or influenced by disease. In other settings the use of non-genetic instrumental variables is possible. A series of examples of the application of these approaches are presented and their potentials and limitations discussed. Other epidemiological strategies are briefly reviewed. It is concluded that the naïve acceptance of findings utilising conventional epidemiological methods in this setting is misplaced.

Conference on "Multidisciplinary approaches to nutritional problems". Postgraduate Symposium. Exploiting dietary supplementation trials to assess the impact of the prenatal environment on CVD risk

Animal studies have demonstrated that altering the maternal diet during pregnancy affects offspring disease risk. Data from human subjects on the early-life determinants of disease have been derived primarily from birth-weight associations; studies of the impact of the maternal diet are scarce and inconsistent. Investigating CVD risk factors in the offspring of women who have participated in maternal supplementation trials provides a useful resource in this research field, by virtue of employing an experimental design (as compared with observational studies). To date, follow-up studies have been published only for a small number of trials; these trials include the impact of maternal protein-energy, multiple-micronutrient and Ca supplementation on offspring disease risk. In Nepal maternal micronutrient supplementation has been shown to be associated with lower offspring systolic blood pressure at 2 years of age. Data from Guatemala on a pre- and postnatal protein-energy community intervention have suggested long-term improvements in fasting glucose and body composition but not in blood pressure. In The Gambia no association has been found between prenatal protein-energy supplementation and markers of CVD risk including body composition, blood pressure and fasting glucose and insulin in childhood and adolescence. Little evidence of an effect of maternal Ca supplementation on offspring blood pressure has been demonstrated in four trials, although the risk of high systolic blood pressure was found to be reduced in one trial. The present paper reviews the current evidence relating maternal nutritional supplementation during pregnancy to offspring CVD risk and explores the potential explanations for the lack of association.

Gestational age and risk factors for cardiovascular disease: evidence from the 1958 British birth cohort followed to mid-life

BACKGROUND

Increases in pre-term births and improved survival rates have led to interest in the association between gestational age and health in adulthood. Associations between gestational age and risk factors for cardiovascular disease have not been fully investigated.

METHODS

Using data from the 1958 British birth cohort (7847 singletons), the associations between gestational age and blood pressure, glycosylated haemoglobin (HbA1c), lipid levels and body mass index (BMI) at age 44-45 years were examined.

RESULTS

After adjustment for sex, birthweight standardized for gestational age and sex and current BMI there was a reduction in systolic blood pressure of 0.53 mmHg (95% CI: 0.32, 0.75) for every 1 week increase in gestational age. There was a non-linear association between gestational age and diastolic blood pressure, with those cohort members born at earlier gestational ages found to have higher diastolic blood pressure than those born at term. These associations remained after adjustments. A 'U'-shaped association was found between gestational age and BMI among women (P = 0.02 for sex x gestational age interaction) which attenuated after adjustment. There was also a weak inverse association between gestational age and total cholesterol specific to women (P = 0.01 for sex x gestational age interaction). No clear associations were found between gestational age and BMI or total cholesterol in men, or between gestational age and HbA1c or other lipid levels in either sex.

CONCLUSIONS

In the 1958 British birth cohort duration of gestation was associated with blood pressure in mid-life. Understanding this association is necessary to inform policy and preventative interventions.

Current status of genome-wide scanning for hypertension

PURPOSE OF REVIEW

The current review focuses on new trends in genome-wide assessment of the inherited component of blood pressure variation.

RECENT FINDINGS

Systematic linkage and association analyses of a region on chromosome 1q, complemented by gene prioritization with comparative genomic evidence, revealed variants in three genes contributing to tangible increases in blood pressure. The results of one of the first two-dimensional scans were published, confirming the oligogenic epistatic nature of the genetic component of blood pressure determination. Several loci with distinct effects on blood pressure in men and women were reported, enhancing the sexually dimorphic map of complex traits. Novel approaches were applied to extract genetically and clinically distinct subsets of garden-variety hypertension, which appears to be a promising direction to take in deciphering the hypertension genetic puzzle.

SUMMARY

The current landscape of genome-wide linkage studies of hypertension is acquiring novel facets in an attempt to more appropriately grasp the genomic architecture of hypertension. The advent of genome-wide association investigations, enhanced possibilities of comparative genomics and integration with information on copy number variations and transcriptomics will most likely reshape our view of nature and the evolutionary connotations of genetic variation affecting blood pressure in the near future.

Sex differences in the associations between birthweight and lipid levels in middle-age: findings from the 1958 British birth cohort

OBJECTIVE

To examine sex differences in birthweight-lipid associations.

METHODS AND RESULTS

Using prospectively collected data on birthweight and non-fasting lipid levels at age 44-45 y from the 1958 British birth cohort (3603 men and 3583 women), sex differences in birthweight-lipid associations were examined. There were inverse associations between birthweight and total and low-density-lipoprotein (LDL)-cholesterol among women (a 1 kg increase in birthweight was associated with a 0.13 mmol/L reduction in total cholesterol (p<0.001) and a 0.07 mmol/L reduction in LDL-cholesterol (p=0.02)) but no associations among men (p=0.005 and p=0.01, respectively, for birthweight x sex interactions). There was an inverse association between birthweight and triglycerides of a similar magnitude in both sexes (a 1 kg increase in birthweight was associated with a 7% reduction in triglyceride levels in sex-adjusted models (p<0.001)). There was no association between birthweight and high-density-lipoprotein-cholesterol. Associations were largely unaltered after adjustment for covariates. Of birthweight, current height and BMI, the latter was the strongest predictor of lipid levels.

CONCLUSIONS

The finding of an inverse association between birthweight and triglycerides in both sexes and of inverse associations between birthweight and total and LDL-cholesterol only in women suggests that the mechanisms underlying the associations with birthweight may vary for different lipids.

Examining life-course influences on chronic disease: the importance of birth cohort studies from low- and middle- income countries. An overview

The objectives of this overview are to describe the past and potential contributions of birth cohorts to understanding chronic disease aetiology; advance a justification for the maintenance of birth cohorts from low- and middle-income countries (LMIC); provide an audit of birth cohorts from LMIC; and, finally, offer possible future directions for this sphere of research. While the contribution of birth cohorts from affluent societies to understanding disease aetiology has been considerable, we describe several reasons to anticipate why the results from such studies might not be directly applied to LMIC. More than any other developing country, Brazil has a tradition of establishing, maintaining and exploiting birth cohort studies. The clear need for a broader geographical representation may be precipitated by a greater collaboration worldwide in the sharing of ideas, fieldwork experience, and cross-country cohort data comparisons in order to carry out the best science in the most efficient manner. This requires the involvement of a central overseeing body--such as the World Health Organization--that has the respect of all countries and the capacity to develop strategic plans for 'global' life-course epidemiology while addressing such issues as data-sharing. For rapid progress to be made, however, there must be minimal bureaucratic entanglements.