Reference equations for evaluation of spirometry function tests in South Asia, and among South Asians living in other countries.

BACKGROUND: There are few data to support accurate interpretation of spirometry data in South Asia, a major global region with a high reported burden of chronic respiratory disease. METHOD: We measured lung function in 7453 healthy men and women aged ≥18 years, from Bangladesh, North India, South India, Pakistan and Sri Lanka, as part of the South Asia Biobank study. First, we assessed the accuracy of existing equations for predicting normal forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and FEV1/FVC ratio. Then, we used our data to derive (n=5589) and internally validate (n=1864) new prediction equations among South Asians, with further external validation among 339 healthy South Asians living in Singapore. RESULTS: The Global Lung Initiative (GLI) and National Health and Nutrition Examination Survey consistently overestimated expiratory volumes (best fit GLI-African American, mean±sd z-score: FEV1 -0.94±1.05, FVC -0.91±1.10; n=7453). Age, height and weight were strong predictors of lung function in our participants (p<0.001), and sex-specific reference equations using these three variables were highly accurate in both internal validation (z-scores: FEV1 0.03±0.99, FVC 0.04±0.97, FEV1/FVC -0.03±0.99) and external validation (z-scores: FEV1 0.31±0.99, FVC 0.24±0.97, FEV1/FVC 0.16±0.91). Further adjustment for study regions improves the model fit, with highest accuracy for estimation of region-specific lung function in South Asia. CONCLUSION: We present improved equations for predicting lung function in South Asians. These offer the opportunity to enhance diagnosis and management of acute and chronic lung diseases in this major global population.

Vitamin B12 deficiency and altered one-carbon metabolites in early pregnancy is associated with maternal obesity and dyslipidaemia.

Vitamin B12 (B12) is a micronutrient essential for one-carbon (1C) metabolism. B12 deficiency disturbs the 1C cycle and alters DNA methylation which is vital for most metabolic processes. Studies show that B12 deficiency may be associated with obesity, insulin resistance and gestational diabetes; and with obesity in child-bearing women. We therefore hypothesised that the associations between B12 deficiency, BMI and the metabolic risk could be mediated through altered 1C metabolites in early pregnancy. We explored these associations in two different early pregnancy cohorts in the UK (cohort 1; n = 244 and cohort 2; n = 60) with anthropometric data at 10-12 weeks and plasma/serum sampling at 16-18 weeks. B12, folate, total homocysteine (tHcy), methionine, MMA, metabolites of 1C metabolism (SAM, SAH) and anthropometry were measured. B12 deficiency (< 150 pmol/l) in early pregnancy was 23% in cohort 1 and 18% in cohort 2. Regression analysis after adjusting for likely confounders showed that B12 was independently and negatively associated with BMI (Cohort 1: ß = - 0.260, 95% CI (- 0.440, - 0.079), p = 0.005, Cohort 2: (ß = - 0.220, 95% CI (- 0.424, - 0.016), p = 0.036) and positively with HDL cholesterol (HDL-C) (ß = 0.442, 95% CI (0.011,0.873), p = 0.045). We found that methionine (ß = - 0.656, 95% CI (- 0.900, - 0.412), p < 0.0001) and SAH (ß = 0.371, 95% CI (0.071, 0.672), p = 0.017) were independently associated with triglycerides. Low B12 status and alteration in metabolites in 1C metabolism are common in UK women in early pregnancy and are independently associated with maternal obesity and dyslipidaemia. Therefore, we suggest B12 monitoring in women during peri-conceptional period and future studies on the pathophysiological relationship between changes in 1C metabolites and its association with maternal and fetal outcomes on larger cohorts. This in turn may offer potential to reduce the metabolic risk in pregnant women and their offspring.

Maternal lipids in pregnancy are associated with increased offspring cortisol reactivity in childhood.

Prenatal programming of hypothalamic-pituitary-adrenal (HPA) axis activity has long term implications for offspring health. Biological mechanisms underlying programming of the offspring HPA axis are poorly understood. We hypothesised that altered maternal metabolism including higher maternal obesity, glucose and lipids are novel programming factors for altered offspring HPA axis activity. Salivary cortisol levels were measured in 54 children aged 3-5 years under experimental conditions (before and after a delay of self-gratification test). Associations of child cortisol responses with maternal obesity in early pregnancy and with fasting glucose, triglycerides, HDL and total cholesterol measured in each pregnancy trimester were tested. Higher levels of maternal triglycerides and total cholesterol throughout pregnancy were associated with increased offspring cortisol reactivity. The associations were independent of maternal obesity and other confounders, suggesting that exposure to maternal lipids could be a biological mechanism of in utero programming of the offspring's HPA axis.

Prenatal exposure to maternal very severe obesity is associated with impaired neurodevelopment and executive functioning in children.

BackgroundPrenatal maternal obesity has been associated with an increased risk of neurocognitive problems in childhood, but there are fewer studies on executive functioning.MethodsTests and questionnaires to assess neurodevelopment, executive functioning, and the ability to delay gratification were conducted in 113 children (mean (SD)=4.24 (0.63) years of age) born to mothers with very severe obesity (SO, body mass index (BMI)⩾40 kg/m2, n=51) or to lean mothers (BMI⩽25 kg/m2, n=62).ResultsPrenatal maternal SO predicted poorer neurodevelopment (unstandardized regression coefficient (B)=-0.42, 95% confidence interval (CI) (-0.82; -0.02)), worse problem-solving (odd ratio (OR)=0.60, 95% CI (1.13; 0.07)), and fine motor skills (OR=4.91, 95% CI (1.27; 19.04)), poorer executive functioning in areas of attention, inhibitory control, and working memory (standardized B=3.75, 95% CI (1.01; 13.93)) but not in self-gratification delay. The effects were independent of maternal concurrent psychological well-being and child's BMI, but not independent of maternal education.ConclusionFuture studies should investigate whether perinatal management of maternal obesity could prevent adverse outcomes in child neurodevelopment.

Maternal distress associates with placental genes regulating fetal glucocorticoid exposure and IGF2: Role of obesity and sex.

Maternal emotional distress symptoms, including life satisfaction, anxiety and depressed mood, are worse in Severely Obese (SO) than lean pregnancy and may alter placental genes regulating fetal glucocorticoid exposure and placental growth. We hypothesised that the associations between increased maternal distress symptoms and changes in placental gene expression including IGF2 and genes regulating fetal glucocorticoid exposure are more pronounced in SO pregnancy. We also considered whether there were sex-specific effects. Placental mRNA levels of 11ß-HSDs, NR3C1-α, NR3C2, ABC transporters, mTOR and the IGF2 family were measured in term placental samples from 43 lean (BMI≤25kg/m(2)) and 50 SO (BMI≥40kg/m(2)) women, in whom distress symptoms were prospectively evaluated during pregnancy. The mRNA levels of genes with a similar role in regulating fetal glucocorticoid exposure were strongly inter-correlated. Increased maternal distress symptoms associated with increased NR3C2 and IGF2 isoform 1(IGF2-1) in both lean and SO group (p≤0.05). Increased distress was associated with higher ABCB1 and ABCG2 mRNA levels in SO but lower ABCB1 and higher 11ß-HSD1 mRNA levels in lean (p≤0.05) suggesting a protective adaptive response in SO placentas. Increased maternal distress associated with reduced mRNA levels of ABCB1, ABCG2, 11ß-HSD2, NR3C1-α and IGF2-1 in placentas of female but not male offspring. The observed sex differences in placental responses suggest greater vulnerability of female fetuses to maternal distress with potentially greater fetal glucocorticoid exposure and excess IGF2. Further studies are needed to replicate these findings and to test whether this translates to potentially greater negative outcomes of maternal distress in female offspring in early childhood.

Mechanisms linking in utero stress to altered offspring behaviour.

Development in utero is recognised as a determinant of health in later life, a concept known as early life 'programming'. Several studies in humans have now shown a link between in utero stressors of maternal stress, anxiety and depression and adverse behavioural outcomes for the offspring including poorer cognitive function and behavioural and emotional problems. These behaviours are observed from the very early neonatal period and appear to persist through to adulthood. Underlying mechanisms are not known but overexposure of the developing foetus to glucocorticoids has been proposed. Dysregulation of the maternal and offspring hypothalamic-pituitary-adrenal (HPA) axis has been proposed as a mechanism linking in utero stress with offspring behavioural outcomes. Studies suggest that altered circulating levels of maternal cortisol during pregnancy and/or changes in placental gene expression or methylation, which result in increased glucocorticoid transfer to the developing foetus, are linked to changes in offspring behaviour and in activity of the offspring HPA axis. Further understanding of the underlying pathways and identification of any gestation of vulnerability are needed to help design interventions to reduce in utero stress and improve behavioural outcomes in the offspring.