Association between Blood Pressure and Birth Weight among Rural South African Children: Ellisras Longitudinal Study

Elevated blood pressure among adolescents in sub-Saharan Africa: a systematic review and meta-analysis

BACKGROUND

More people from sub-Saharan Africa aged between 20 years and 60 years are affected by end-organ damage due to underlying hypertension than people in high-income countries. However, there is a paucity of data on the pattern of elevated blood pressure among adolescents aged 10-19 years in sub-Saharan Africa. We aimed to provide pooled estimates of high blood pressure prevalence and mean levels in adolescents aged 10-19 years across sub-Saharan Africa.

METHODS

In this systematic review and meta-analysis, we searched PubMed, Google Scholar, African Index Medicus, and Embase to identify studies published from Jan 1, 2010, to Dec 31, 2021. To be included, primary studies had to be observational studies of adolescents aged 10-19 years residing in sub-Saharan African countries reporting the pooled prevalence of elevated blood pressure or with enough data to compute these estimates. We excluded studies on non-systemic hypertension, in African people not living in sub-Saharan Africa, with participant selection based on the presence of hypertension, and with adult cohorts in which we could not disaggregate data for adolescents. We independently extracted relevant data from individual studies using a standard data extraction form. We used a random-effects model to estimate the pooled prevalence of elevated blood pressure and mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) levels overall and on a sex-specific basis. This study is registered with PROSPERO (CRD42022297948).

FINDINGS

We identified 2559 studies, and assessed 81 full-text studies for eligibility, of which 36 studies comprising 37 926 participants aged 10-19 years from ten (20%) of 49 sub-Saharan African countries were eligible. A pooled sample of 29 696 adolescents informed meta-analyses of elevated blood pressure and 27 155 adolescents informed meta-analyses of mean blood pressure. Sex data were available from 26 818 adolescents (14 369 [53·6%] were female and 12 449 [46·4%] were male) for the prevalence of elevated blood pressure and 23 777 adolescents (12 864 [54·1%] were female and 10 913 [45·9%] were male) for mean blood pressure. Study quality was high, with no low-quality studies. The reported prevalence of elevated blood pressure ranged from 4 (0·2%) of 1727 to 1755 (25·1%) of 6980 (pooled prevalence 9·9%, 95% CI 7·3-12·5; I?=99·2%, p_{heterogeneity}<0·0001). Mean SBP was 111 mm Hg (95% CI 108-114) and mean DBP was 68 mm Hg (66-70). 13·4% (95% CI 12·9-13·9; p_{heterogeneity}<0·0001) of male participants had elevated blood pressure compared with 11·9% (11·3-12·4; p_{heterogeneity}<0·0001) of female participants (odds ratio 1·04, 95% CI 0·81-1·34; p_{heterogeneity}<0·0001).

INTERPRETATION

To our knowledge, this systematic review and meta-analysis is the first systematic synthesis of blood pressure data specifically derived from adolescents in sub-Saharan Africa. Although many low-income countries were not represented in our study, our findings suggest that approximately one in ten adolescents have elevated blood pressure across sub-Saharan Africa. Accordingly, there is an urgent need to improve preventive heart-health programmes in the region.

FUNDING

None.

Birth weight influences differently on systolic and diastolic blood pressure in children and adolescents aged 8-15

AIM

Globally, hypertension is one of the main threats to public health and a significant risk factor predisposing individuals to various cardiovascular conditions. Hypertension in the young is particularly complex and challenging. Accumulating evidence has implicated that low birth weight is vital for elevated blood pressure, and birth weight was negatively correlated with blood pressure. However, fewer studies with conflicting results have addressed the associations between birth weight and blood pressure in children and adolescents, and there is no relevant research conducted in the NHANES population. The principal objective of this project was to investigate the relationship between birth weight and blood pressure in children and adolescents in NHANES.

METHODS

A total of 7600 subjects aged 8 to15 were enrolled in the present study from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. Outcome variables were systolic blood pressure(SBP) and diastolic blood pressure(DBP). Birth weight was regarded as an independent variable. EmpowerStats software and R (version 3.4.3) were performed to examine the association between birth weight and SBP or DBP.

RESULTS

Birth weight was negatively correlated with SBP in the fully-adjusted model(β = -0.02, 95%CI: -0.04 to -0.04, p = 0.0013), especially in non-Hispanic White (β = -0.03, 95%CI: -0.06 to -0.00,p = 0.0446), aged between 13 to 15(β = -0.03, 95%CI: -0.04 to -0.01, p = 0.0027), and male individuals(β = -0.03, 95%CI: -0.05 to -0.01, p = 0.0027). However, there was no unidirectional association between birth weight and DBP in the fully adjusted model(β = -0.01, 95%CI: -0.03 to 0.02, p = 0.5668) and in sub-analysis. An inverted U-shaped and J-shaped relationship was uncovered between birth weight and DBP in those aged 13 or above and Mexican Americans, respectively. The inflection point calculated by a recursive algorithm of birth weight in these groups was all 105 oz.

CONCLUSIONS

The current study identified that birth weight was negatively related to SBP but not significantly related to DBP in children and adolescents aged 8 to 15, highlighting different potential mechanisms behind high SBP and high DBP in the young. However, an inverted U-shaped and J-shaped relationship between birth weight and DBP was observed, suggesting that targeted intervention measures should be taken for different groups of people rather than generalizations.

Association of blood pressure with dietary intake, physical activity, and anthropometric measurements in Turkish adolescents

Background

Determining high blood pressure in childhood is an important step to reduce the risk of occurrence of high blood pressure-related diseases in adulthood.

Aims

This study aimed to assess the association of blood pressure with dietary intake, physical activity, and anthropometric measurements in Turkish adolescents.

Patients and Methods

This cross-sectional study included 370 students (202 females, 168 males) aged 14 to 18 years from one private and one public school in Kayseri, Turkey. Some anthropometric measurements and 24-hour dietary recall of the students were obtained. Their blood pressures were measured, and the International Physical Activity Questionnaire and the Mediterranean Diet Quality Index (KIDMED) were used.

Results

The body mass index (BMI) mean and waist/height ratio of the hypertensive group were significantly higher than those of the prehypertensive group, whereas their daily potassium, calcium, and magnesium intakes were significantly lower than those of the normotensive group. The percentage of individuals with very low diet quality was higher in the hypertensive group than in the normotensive group (P > 0.05). The percentage of participants with sufficient physical activity was higher in the normotensive group than in the prehypertensive and hypertensive groups.

Conclusion

Factors such as high BMI and waist/height rates; low calcium, magnesium, and potassium intakes with diet; insufficient physical activity; and low quality of diet might cause an increase in the blood pressure.

Association between maternal iron supplementation and newborn birth weight: a quantile regression analysis

Objective

Our study aimed to explore the association between maternal iron supplementation and newborn birth weight (BW) in Shaanxi Province using quantile regression (QR).

Method

The data used in this study were derived from a large cross-sectional survey of a population in Shaanxi Province, Northwest China. A total of 28,209 women and their infants were selected using a stratified multistage random sampling method. The effect of iron supplementation on the newborn BW was assessed by a multiple linear regression model and QR.

Results

A total of 5.15% of the women took iron supplements during pregnancy. Multiple linear regression showed that the iron supplementation during pregnancy had positive effects on the BW, with an average increase of 43.07 g (β = 43.07, t = 3.55, and p < 0.001). The QR showed that the iron supplementation during pregnancy was associated with an increased newborn BW from very low to higher percentiles (quantiles: 0 ~ 0.40), with the β ranging from 136.51 to 43.86. As the percentiles of the BW increased, the neonatal BW gain gradually declined in the iron supplementation group compared with the group that did not receive iron supplementation (quantiles: 0 ~ 0.40, with the β ranging from 136.51 to 43.86). Iron supplementation was more effective among women who suffered from anemia during pregnancy (β = 45.84, t = 2.05, and p = 0.04; quantiles: 0 ~ 0.15, 0.30, 0.80, with β ranging from 150.00 to 39.29) than it was in any other group (β = 38.18, t = 2.62, and p = 0.009; quantiles: 0 ~ 0.15, with β ranging from 133.33 to 28.32).

Conclusions

Iron supplementation during pregnancy is associated with an increased newborn BW, and the effect was more obvious in the newborns with the lower BW and newborns whose mothers suffered from anemia during pregnancy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13052-021-01084-7.

The Relationship between Under-Nutrition and Hypertension among Ellisras Children and Adolescents Aged 9 to 17 Years

Background: Globally, under-nutrition and hypertension in children has been associated with the risk of developing cardiovascular disease (CVD) in adulthood. The main objective of this study was to investigate the relationship between under-nutrition and hypertension, furthermore, to determine the risk of developing hypertension due to under-nutrition. Methods: The study comprised of 1701 participants (874 boys and 827 girls) between the ages of 9 and 17 years old. All anthropometric and blood pressure measurements were taken according to standard procedures. Mid-upper arm circumference (MUAC), body mass index (BMI), upper arm fat area (UFA), total upper arm area (TUAA) and upper arm muscle area (UMA) of Ellisras children were compared with the National Health and Nutrition Examination Survey III reference population. The linear regression models were used to determine the relationship between under-nutrition with hypertension for unadjusted and then adjusted for age and gender. The logistic regression model was used to determine the risk of under-nutrition on developing hypertension for unadjusted and adjusted for age and gender. Results: There was a positive significant (p < 0.0001) association between all under-nutrition variables (MUAC, BMI, UFA, TUAA and UMA) and systolic blood pressure (SBP; beta ranges between 0.84 and 2.78), and diastolic blood pressure (DBP; beta ranges between 0.3 and 1.08 before adjusting and after adjusting for age and gender (SBP, beta ranges between 0.59 and 2.00 and DBP (beta ranges between 0.24 and 0.80. Conclusion: The prevalence of under-nutrition was high while the prevalence of hypertension was low in this study. The mean under-nutrition variables (BMI, UFA, UMA and MUAC) of Ellisras children were far lower compared to the NHANES III reference population. Hypertension was significantly associated with under-nutrition in this study.