Shortness at birth is associated with insulin resistance in pre-pubertal Jamaican children

Associations of stunting in early childhood with cardiometabolic risk factors in adulthood

Early life stunting may have long-term effects on body composition, resulting in obesity-related comorbidities. We tested the hypothesis that individuals stunted in early childhood may be at higher cardiometabolic risk later in adulthood. 1753 men and 1781 women participating in the 1982 Pelotas (Brazil) birth cohort study had measurements of anthropometry, body composition, lipids, glucose, blood pressure, and other cardiometabolic traits at age 30 years. Early stunting was defined as height-for-age Z-score at age 2 years below -2 against the World Health Organization growth standards. Linear regression models were performed controlling for sex, maternal race/ethnicity, family income at birth, and birthweight. Analyses were stratified by sex when p-interaction<0.05. Stunted individuals were shorter (β = -0.71 s.d.; 95% CI: -0.78 to -0.64), had lower BMI (β = -0.14 s.d.; 95%CI: -0.25 to -0.03), fat mass (β = -0.28 s.d.; 95%CI: -0.38 to -0.17), SAFT (β = -0.16 s.d.; 95%CI: -0.26 to -0.06), systolic (β = -0.12 s.d.; 95%CI: -0.21 to -0.02) and diastolic blood pressure (β = -0.11 s.d.; 95%CI: -0.22 to -0.01), and higher VFT/SAFT ratio (β = 0.15 s.d.; 95%CI: 0.06 to 0.24), in comparison with non-stunted individuals. In addition, early stunting was associated with lower fat free mass in both men (β = -0.39 s.d.; 95%CI: -0.47 to -0.31) and women (β = -0.37 s.d.; 95%CI: -0.46 to -0.29) after adjustment for potential confounders. Our results suggest that early stunting has implications on attained height, body composition and blood pressure. The apparent tendency of stunted individuals to accumulate less fat-free mass and subcutaneous fat might predispose them towards increased metabolic risks in later life.

Environmental exposure to lithium during pregnancy and fetal size: a longitudinal study in the Argentinean Andes

BACKGROUND

Lithium, used for treating bipolar disease, crosses freely the placenta and is classified as teratogenic. It is unclear to what extent environmental lithium exposure may affect fetal growth and development.

OBJECTIVES

To elucidate potential effects of lithium exposure through drinking water during pregnancy on fetal size.

METHODS

We developed a prospective population-based mother-child cohort (N=194) in an area with highly varying drinking water lithium concentrations (5-1600 μg/L) in northern Argentinean Andes. Blood and urinary lithium concentrations (sampled repeatedly during pregnancy) were measured using inductively coupled plasma mass spectrometry. We measured fetal size by ultrasound in second and third trimesters, and weight, length and head circumference at birth. Multivariable models were used to examine associations between lithium exposure (continuous and in tertiles) and fetal size measures.

RESULTS

Lithium in maternal blood (median 25; range 1.9-145 μg/L) and urine (1645; 105-4600 μg/L) was inversely associated (apparently linearly) with all fetal measures (body, head and femur) in the second trimester, and with birth length (β -0.53 cm per 25 μg/L increase in blood lithium, 95%CI -1.0; -0.052). An increase of 100 μg/L in blood was associated with 2 cm shorter newborns (about one standard deviation).

CONCLUSIONS

Lithium exposure through drinking water was associated with impaired fetal size and this seemed to be initiated in early gestation. Further studies are warranted to confirm causality and to understand the mechanisms. If confirmed, these findings have public health relevance and emphasize the need for more data on lithium concentrations in drinking water, including bottled water.

Low birth weight, nephron number, and kidney disease

More and more evidence is emerging that highlights the far-reaching consequences of prenatal (intrauterine) programming on organ function and adult disease. In humans, low birth weight (LBW) occurs more frequently in disadvantaged communities among whom there is often a disproportionately high incidence of adult cardiovascular disease, hypertension, diabetes mellitus, and kidney disease. Indeed, many epidemiologic studies have found an inverse association between LBW and higher blood pressures in infancy and childhood, and overt hypertension in adulthood. Multiple animal models have demonstrated the association of LBW with later hypertension, mediated, at least in part, by an associated congenital nephron deficit. Although no direct correlation has been shown between nephron number and birth weight in humans with hypertension, nephron numbers were found to be lower in adults with essential hypertension, and glomeruli tend to be larger in humans of lower birth weight. An increase in glomerular size is consistent with hyperfiltration necessitated by a reduction in total filtration surface area, which suggests a congenital nephron deficit. Hyperfiltration manifests clinically as microalbuminuria and accelerated loss of renal function, the prevalence of which are higher among adults who had been of LBW. A kidney with a reduced nephron number has less renal reserve to adapt to dietary excesses or to compensate for renal injury, as is highlighted in the setting of renal transplantation, where smaller kidney to recipient body-weight ratios are associated with poorer outcomes, independent of immunologic factors. Both hypertension and diabetes are leading causes of end-stage renal disease worldwide, and their incidences are increasing, especially in underdeveloped communities. Perinatal programming of these 2 diseases, as well as of nephron number, may therefore have a synergistic impact on the development of hypertension and kidney disease in later life. Existing evidence suggests that birth weight should be used as a surrogate marker for future risk of adult disease. Although the ideal solution to minimize morbidity would be to eradicate LBW, until this panacea is realized, it is imperative to raise awareness of its prognostic implications and to focus special attention toward early modification of risk factors for cardiovascular and renal disease in individuals of LBW.

Maternal body composition, offspring blood pressure and the hypothalamic-pituitary-adrenal axis

We tested the hypothesis that women who are thin or have poor pregnancy weight gain have offspring with higher blood pressure and examined whether this link is mediated by increased secretion of cortisol. We studied a cohort of 388 children born in Kingston, Jamaica. From hospital records we obtained information about their mother's body mass index (BMI) and weight gain during pregnancy. At age 8.5 years we measured the children's fasting plasma cortisol concentrations and blood pressure and assessed their mother's anthropometry. There were no relationships between the mother's BMI or weight gain during pregnancy and offspring blood pressure. However, mothers with a greater subscapular to triceps skinfold thickness ratio (SSTR) had offspring with higher blood pressure (5.6 mmHg systolic and 3.7 mmHg diastolic increase per unit change in SSTR, P = 0.002 and P = 0.008 respectively). Fasting plasma cortisol concentrations correlated with the children's systolic (r = 0.33, P < 0.0001) and diastolic pressures (r = 0.12, P = 0.02) independently of age, gender, weight or socio-economic status and were also predicted by the mother's SSTR. These findings suggest that maternal truncal obesity rather than thinness is associated with raised blood pressure in the offspring, and that this link may be mediated by increased cortisol secretion.

Growth trajectory evident at birth affects age of first delivery in female monkeys

Growth trajectories established early in life have proven to be important determinants of metabolism, health in adulthood, and ultimate mortality. The age of sexual maturation may also be set early in development, perhaps etched in utero. The following study used growth curve modeling to investigate the degree to which birth weight and weight gain before sexual maturation constrained the timing of reproduction in 147 female rhesus monkeys living under standardized social and nutritional conditions. Although size at birth by itself did not determine age of reproductive maturation, it was strongly associated with the subsequent developmental growth trajectory, which in turn predicted age at first offspring. In contrast to human studies indicating that small birth size is followed by a postnatal "catch-up" growth phase that accelerates menarche, growth trajectories remained distinctive in small and large infant monkeys. Thus, it was the sustained and stable disparity in size already evident at birth and amplified through development that accounted for variation in the age of adult sexual maturity.