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

Estimation of the causal effect of sex on neonatal intensive care unit outcomes among very low birth weight infants

OBJECTIVE

Estimate the causal effect of sex on outcomes in the neonatal intensive care unit (NICU) among very low birth weight (VLBW) infants.

STUDY DESIGN

Retrospective cohort study using Vermont Oxford Network data to compare NICU outcomes for VLBW males versus females. Odds ratios (OR) for outcomes that differed significantly by sex were computed using standard unweighted analysis and inverse probability weighted (IPW) analysis to correct for selection bias.

RESULTS

Using standard analysis, males were significantly more likely to die before discharge and experience six other adverse outcomes. From IPW analysis, male sex caused a 56% increase in the odds of death before discharge (OR = 1.56, 95% confidence interval: 1.18-1.94). Standard unweighted results were significantly biased towards increased risk of adverse outcomes for males (p = 0.005) compared to IPW results for which three outcomes were no longer significantly associated with male sex.

CONCLUSION

Standard statistical methods generally overestimate the casual effect of sex among VLBW infants.

Associations of birth weight, plasma metabolome in adulthood and risk of type 2 diabetes

AIMS

We aimed to examine the longitudinal associations of birth weight with plasma metabolites in adulthood, and further quantify the proportions of the links between birth weight and incident adult type 2 diabetes (T2D) that were mediated by plasma metabolites.

MATERIALS AND METHODS

A total of 62,033 participants with complete nuclear magnetic resonance metabolomics and birth weight data from the UK Biobank were included in this study. Linear regression was used to assess the associations between birth weight and metabolites. Cox regression was used to estimate hazard ratios for T2D associated with metabolites. We further performed mediation analyses to estimate the extent to which metabolites might mediate the association between birth weight and T2D risk.

RESULTS

Low birth weight was associated with the adverse metabolic responses across multiple metabolic pathways, including lipoprotein subclasses, amino acids, fatty acids (FA), and inflammation. Metabolites associated with higher birth weight tended to be associated with a lower risk of T2D (Pearson correlation coefficient: -0.85). A total of 62 metabolites showed statistically significant mediation effects in the protective association of higher birth weight and T2D risk, including large-sized very low-density lipoprotein particles and triglyceride concentrations as well as saturated, and monounsaturated FA and glycoprotein acetyls.

CONCLUSIONS

We identified a range of metabolites that reflect the adult metabolic response to birth weight, some of which might lie on the pathway between birth weight and adult T2D risk.

Sex-specific alterations in hepatic cholesterol metabolism in low birth weight adult guinea pigs

BACKGROUND

Intrauterine growth restriction and low birth weight (LBW) have been widely reported as an independent risk factor for adult hypercholesterolaemia and increased hepatic cholesterol in a sex-specific manner. However, the specific impact of uteroplacental insufficiency (UPI), a leading cause of LBW in developed world, on hepatic cholesterol metabolism in later life, is ill defined and is clinically relevant in understanding later life liver metabolic health trajectories.

METHODS

Hepatic cholesterol, transcriptome, cholesterol homoeostasis regulatory proteins, and antioxidant markers were studied in UPI-induced LBW and normal birth weight (NBW) male and female guinea pigs at 150 days.

RESULTS

Hepatic free and total cholesterol were increased in LBW versus NBW males. Transcriptome analysis of LBW versus NBW livers revealed that "cholesterol metabolism" was an enriched pathway in LBW males but not in females. Microsomal triglyceride transfer protein and cytochrome P450 7A1 protein, involved in hepatic cholesterol efflux and catabolism, respectively, and catalase activity were decreased in LBW male livers. Superoxide dismutase activity was reduced in LBW males but increased in LBW females.

CONCLUSIONS

UPI environment is associated with a later life programed hepatic cholesterol accumulation via impaired cholesterol elimination in a sex-specific manner. These programmed alterations could underlie later life cholesterol-induced hepatic lipotoxicity in LBW male offspring.

IMPACT

Low birth weight (LBW) is a risk factor for increased hepatic cholesterol. Uteroplacental insufficiency (UPI) resulting in LBW increased hepatic cholesterol content, altered hepatic expression of cholesterol metabolism-related genes in young adult guinea pigs. UPI-induced LBW was also associated with markers of a compromised hepatic cholesterol elimination process and failing antioxidant system in young adult guinea pigs. These changes, at the current age studied, were sex-specific, only being observed in LBW males and not in LBW females. These programmed alterations could lead to further hepatic damage and greater predisposition to liver diseases in UPI-induced LBW male offspring as they age.

Complicaciones cardiovasculares en relación con la programación fetal

Introducción: la programación fetal ofrece nuevas perspectivas sobre el origen de las enfermedades cardiovasculares, relacionando su aparición con factores perinatales. Objetivo: exponer evidencia que vincule las alteraciones gestacionales con las enfermedades cardiovasculares en la vida adulta del feto. Metodología: búsqueda en las bases de datos EBSCO, COCHRANE, MEDLINE, PROQUEST y SciELO de los artículos de revisión e investigaciones originales en inglés publicados en los últimos diez años. Se utilizaron términos MeSH para búsqueda controlada y se evaluaron los estudios con STROBE y PRISMA según correspondía. Resultados: los hallazgos sugieren que nacer con menos de 2600 k guarda relación con diabetes mellitus (OR de 1.607 IC 95% 1.324-1.951), hipertensión arterial (OR de 1.15 IC 95% 1.043-1.288) y menor función endotelial (1.94+0.37 vs 2.68+0.41, p: 0.0001) en la adultez. La prematuridad se asocia con mayores presiones arteriales sistólicas (4.2 mmHg IC 95%; 2.8 - 5.7 p 0.001) y diastólicas (2.6 mmHg IC 95%; 1.2-4.0; p 0.001). Las alteraciones nutricionales maternas y la diabetes gestacional aumentan el riesgo de síndrome metabólico (OR 1.2 IC 95% 0.9-1.7) y sobrepeso en la edad escolar (OR 1.81 IC 95% 1.18 - 2.86). Conclusión: los resultados adversos en la gestación están relacionados con el desarrollo de enfermedades cardiovasculares en la vida adulta del feto expuesto.

Lifecourse body mass index trajectories and cardio-metabolic disease risk in Guatemalan adults

Little is known about body size over the life-course and non-communicable disease risk in low- and middle-income country populations. Our study explored the role of body mass index (BMI) trajectories from infancy through mid-adulthood on cardio-metabolic disease (CMD) risk factors in a prospective cohort of Guatemalan adults. Study participants were born in Guatemala from 1962-77 and have been followed prospectively since participating in a nutrition supplementation trial as children. Sex-specific BMI latent class trajectories were derived using latent class growth modeling from up to 22 possible BMI values from age 1 month to 42 years measured between 1969 and 2004. CMD risk factors were assessed in 2015-17 (at age 37-54 years) using anthropometry, blood glucose and lipids, and blood pressure. We used logistic regression to assess the role of BMI trajectory on CMD risk factors in 510 women and 346 men (N = 856). We identified two BMI latent classes for women (low [n = 287, 56.3%] and high [n = 223, 43.7%]) and three classes for men (low [n = 141, 40.8%], medium [n = 160, 46.2%], and high [n = 45, 13.0%]). Given the small percentage of men in the high BMI latent class, we collapsed the medium and high BMI latent classes for men (n = 205, 59.1%). Among the most prevalent CMD risk factors at ages 37-54 years were abdominal obesity defined by waist-height ratio (99.6% of women and 87.3% of men), obesity defined by percent body fat (96.6% of women and 75.9% of men), low HDL-c (87.5% of women and 74.5% of men), and elevated triglycerides (78.3% of women and 73.6% of men). Except for obesity defined by BMI, we found no associations between BMI latent class and CMD risk factors in women. Among men, BMI latent class was not associated with CMD risk factors after controlling for current BMI. For the CMD risk factors we analyzed, the role of early life BMI on adult CMD appeared to be mediated by adult BMI among men-highlighting the need to establish and maintain healthy body weight over the life course.

Exposure to improved nutrition from conception to age 2 years and adult cardiometabolic disease risk: a modelling study

BACKGROUND

Low-income and middle-income countries with populations that are chronically undernourished in early life are undergoing a nutrition transition and are experiencing an epidemic of cardiometabolic disease. These dual burdens are thought to be causally related; therefore, the extent to which improvements in early-life nutrition can offset adult-onset disease is important. The aim of this study was to examine whether improvement of protein-energy nutrition from conception to age 2 years can attenuate the risk of cardiometabolic disease.

METHODS

We followed up a cohort of 2392 individuals born between Jan 1, 1962, and Feb 28, 1977, in four villages in Guatemala who had participated in a cluster-randomised protein-energy nutritional supplementation (Atole) trial. Of 1661 participants available for follow-up from Feb 26, 2015, to April 29, 2017, we studied 684 women and 455 men. We assessed cardiometabolic disease risk at ages 37-54 years using anthropometry, fasting and post-challenge glucose, fasting lipid concentrations, and blood pressure. We used generalised linear and logistic regression modelling to estimate the effect of Atole from conception to age 2 years (the first 1000 days) on cardiometabolic disease risk.

FINDINGS

Exposure to Atole from conception to age 2 years was associated with increased fatness (body-mass index [1·29 kg/m2, 95% CI 0·08 to 2·50], body fat [1·73%, 0·20 to 3·26], and obesity [odds ratio 1·94, 1·11 to 3·40]), diastolic blood pressure (1·59 mm Hg, -0·74 to 3·92), and blood lipids (total cholesterol [10·10 mg/dL, 0·80 to 19·40] and non-HDL cholesterol [10·41 mg/dL, 1·51 to 19·31]), reduced post-challenge glucose (-5·84 mg/dL, -12·51 to 0·83), and reduced odds of diabetes (odds ratio 0·46, 0·21 to 0·97). We found stratum heterogeneity by sex in pooled models for non-HDL cholesterol (4·34 mg/dL, 95% CI -6·86 to 15·55 for women vs 19·84 mg/dL, 5·86 to 33·82 for men) and post-challenge glucose (-0·19 mg/dL, -8·63 to 8·24 for women vs -13·10 mg/dL, -23·64 to -2·56 for men). p values for interaction of sex and exposure to Atole from conception to age 2 years were 0·09 and 0·04, respectively.

INTERPRETATION

Improved protein-energy nutrition from conception to the 2nd birthday reduced the odds of diabetes at ages 37-54 years; however, this protein-energy supplementation also increased the risk of obesity and several obesity-related conditions. Our findings suggest a mixed ability of protein-energy nutritional supplementation in early life to prevent adult cardiometabolic disease incidence in the context of high childhood stunting and high adult overweight and obesity.

FUNDING

National Institutes of Health.

Obesity in Low- and Middle-Income Countries: Burden, Drivers, and Emerging Challenges

We have reviewed the distinctive features of excess weight, its causes, and related prevention and management efforts, as well as data gaps and recommendations for future research in low- and middle-income countries (LMICs). Obesity is rising in every region of the world, and no country has been successful at reversing the epidemic once it has begun. In LMICs, overweight is higher in women compared with men, in urban compared with rural settings, and in older compared with younger individuals; however, the urban–rural overweight differential is shrinking in many countries. Overweight occurs alongside persistent burdens of underweight in LMICs, especially in young women. Changes in the global diet and physical activity are among the hypothesized leading contributors to obesity. Emerging risk factors include environmental contaminants, chronic psychosocial stress, neuroendocrine dysregulation, and genetic/epigenetic mechanisms. Data on effective strategies to prevent the onset of obesity in LMICs or elsewhere are limited. Expanding the research in this area is a key priority and has important possibilities for reverse innovation that may also inform interventions in high-income countries.

Body composition and the monitoring of non-communicable chronic disease risk

There is a need for simple proxies of health status, in order to improve monitoring of chronic disease risk within and between populations, and to assess the efficacy of public health interventions as well as clinical management. This review discusses how, building on recent research findings, body composition outcomes may contribute to this effort. Traditionally, body mass index has been widely used as the primary index of nutritional status in children and adults, but it has several limitations. We propose that combining information on two generic traits, indexing both the ‘metabolic load’ that increases chronic non-communicable disease risk, and the homeostatic ‘metabolic capacity’ that protects against these diseases, offers a new opportunity to improve assessment of disease risk. Importantly, this approach may improve the ability to take into account ethnic variability in chronic disease risk. This approach could be applied using simple measurements readily carried out in the home or community, making it ideal for M-health and E-health monitoring strategies.

The effect of intra-uterine growth restriction on blood lipids and response to exercise training

OBJECTIVES

To determine if a small body size at birth is associated with an unfavorable metabolic profile and a reduced response to exercise training in young adults.

METHODS

Thirty-six college students, all singletons born to term, participated. Subjects were defined as either high ponderal index (HIGHPI) or low ponderal index (LOWPI). LOWPI was defined as below the 10th percentile of the PI-for-gestational age distribution. HIGHPI was defined as greater than the 10th percentile. Subject groups were matched pair-wise on age, sex, BMI, and pretraining physical activity level. Subjects completed an 8-week aerobic exercise program. Pre- and post-training measurements included a blood lipid profile.

RESULTS

The LOWPI group, when compared to the HIGHPI group, exhibited higher total (183.6 mg dl(-1) vs. 150.9, P = 0.04) and LDL cholesterol (114.8 mg dl(-1) vs. 80.2, P = 0.019) values prior to exercise training. After training, these values decreased in the LOWPI group, eliminating the group difference. Various blood lipid ratios were more favorable for the HIGHPI group, both before and after training. The inclusion of maternal smoking as a covariate attenuated group differences for pretraining TChol, pre-training TG:HDL, and post-training HDL cholesterol.

CONCLUSIONS

An 8-week exercise program corrected some, but not all, of the differences in blood lipid values between the LOWPI and HIGHPI group. The persistent group difference in blood lipid ratios suggests a higher long-term risk of chronic disease in the LOWPI group independent of lifestyle intervention.

Life course body mass index, birthweight and lipid levels in mid-adulthood: a nationwide birth cohort study

AIMS

Improvement in lipid profiles is an important public health and clinical goal for which a better understanding is needed of biological pathways and influences. Evidence is scant on the role of growth, including trajectories of body mass index (BMI), so we aimed to determine whether particular life stages from birth to adulthood are important for lipid levels in mid-adulthood (45 years).

METHODS AND RESULTS

In the 1958 British birth cohort (n = 3927 men; 3897 women), weight and height were recorded at: birth (weight only), 7, 11, 16, 23, 33, and 45 years. Birthweight was inversely associated with triglycerides and in women with total- and non-high-density lipoprotein cholesterol; associations were little affected by adjustment for 7-year BMI. Associations between lipids and BMI strengthened with age, e.g. in women, adult (45-year) triglycerides were elevated by 1.54% (95% confidence interval: 0.87-2.21%) and 3.57% (3.29-3.86%), respectively, per kg/m² higher BMI at 11 and 45 years. Body mass index gain was related to lipids, with strongest associations for the interval between 33 and 45 years, where a kg/m² gain in BMI was associated with ~0.6% higher total cholesterol and ~5.3% higher triglycerides. Associations between 45-year BMI and lipids were stronger for those with lowest than highest BMI at younger ages (P for interaction ≤0.05). A long duration of obesity and obesity in childhood but not thereafter were unrelated to adult lipid levels.

CONCLUSIONS

Our findings from a large population-based cohort highlight detrimental consequences of high adult BMI for lipids as most pronounced for those with a lower BMI at earlier life stages.

Ethnic variability in adiposity, thrifty phenotypes and cardiometabolic risk: addressing the full range of ethnicity, including those of mixed ethnicity

Ethnic groups vary in cardiometabolic risk, but the underlying mechanisms remain unclear. Several components of body composition variability (fat/lean ratio, fat distribution, lean mass composition and metabolism, and adipose tissue biology) are increasingly linked with cardiometabolic risk and vary substantially across ethnic groups. Constituents of lean mass are proposed to contribute to 'metabolic capacity', a generic trait favouring the maintenance of homeostasis. Adiposity is proposed to contribute to 'metabolic load', which at higher levels challenges metabolic homeostasis, elevating cardiometabolic risk. Ethnic differences in body composition, representing different load-capacity ratios, may therefore contribute to ethnic variability in cardiometabolic risk. Ecological and evolutionary factors potentially contributing to ethnic variability in body composition are explored. In contemporary populations, clinicians encounter an increasing range of ethnicity, along with many individuals of mixed-ethnic ancestry. Increasing understanding of the contribution of body composition to cardiometabolic risk may reduce the need to treat ethnic groups as qualitatively different. A conceptual model is proposed, treating insulin sensitivity and stroke risk as composite functions of body composition variables. Operationalizing this model may potentially improve the ability to assess cardiovascular risk across the full ethnicity spectrum, and to predict cardiometabolic consequences of excess weight gain.

Estimated birth weight and adult cardiovascular risk factors in a developing southern Chinese population: a cross sectional study

Background

Birth weight is negatively associated with cardiovascular diseases and diabetes, but the associations are less well-established in developing populations where birth weight is often unavailable. We studied the association of birth weight and cardiovascular risk, using birth rank as an instrumental variable, in Southern China.

Methods

We used published data on birth weight by birth rank from an appropriate population and baseline data from the Guangzhou Biobank Cohort Study phases 2 & 3 (2005-8) to examine the adjusted associations, using instrumental variable analysis, of birth weight with clinically measured cardiovascular risk factors and the metabolic syndrome in older (≥ 50 years) men (n = 5,051) and women (n = 13,907).

Results

Estimated birth weight was associated with lower blood pressure (systolic -0.25 mm Hg 95% confidence interval (CI), -0.53 to 0.03 and diastolic -0.33 mm Hg 95% CI -0.48 to -0.18 per standard deviation higher birth weight), but had little association with glucose, lipids, waist-hip ratio, body mass index or the metabolic syndrome, adjusted for age, sex, early environment and number of offspring.

Conclusion

Birth weight may impact blood pressure; however associations of birth weight with other cardiovascular risk factors may not be related to foetal exposures, but speculatively could be an historical co-incidence, with corresponding implications for prevention.

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.