Timing of infant formula introduction in relation to BMI and overweight at ages 1 and 3 years: the Born in Guangzhou Cohort Study (BIGCS).

Mounting evidence suggests that the first few months of life are critical for the development of obesity. The relationships between the timing of solid food introduction and the risk of childhood obesity have been examined previously; however, evidence for the association of timing of infant formula introduction remains scarce. This study aimed to examine whether the timing of infant formula introduction is associated with growth z-scores and overweight at ages 1 and 3 years. This study included 5733 full-term (≥ 37 gestational weeks) and normal birth weight (≥ 2500 and < 4000 g) children in the Born in Guangzhou Cohort Study, a prospective cohort study with data collected at 6 weeks, 6, 12 and 36 months. Compared with infant formula introduction at 0-3 months, introduction at 4-6 months was associated with the lower BMI, weight-for-age and weight-for-length z-scores at 1 and 3 years old. Also, introduction at 4-6 months was associated with the lower odds of at-risk of overweight at age 1 (adjusted OR 0·72, 95 % CI 0·55, 0·94) and 3 years (adjusted OR 0·50, 95 % CI 0·30, 0·85). Introduction at 4-6 months also decreased the odds of overweight at age 1 year (adjusted OR 0·42, 95 % CI 0·21, 0·84) but not at age 3 years. Based on our findings, compared with introduction within the first 3 months, introduction at 4-6 months has a reduction on later high BMI risk and at-risk of overweight. However, these results need to be replicated in other well-designed studies before more firm recommendations can be made.

Long-term ambient air pollution exposure and cardio-respiratory disease in China: findings from a prospective cohort study.

BACKGROUND: Existing evidence on long-term ambient air pollution (AAP) exposure and risk of cardio-respiratory diseases in China is mainly on mortality, and based on area average concentrations from fixed-site monitors for individual exposures. Substantial uncertainty persists, therefore, about the shape and strength of the relationship when assessed using more personalised individual exposure data. We aimed to examine the relationships between AAP exposure and risk of cardio-respiratory diseases using predicted local levels of AAP. METHODS: A prospective study included 50,407 participants aged 30-79 years from Suzhou, China, with concentrations of nitrogen dioxide (NO2), sulphur dioxide (SO2), fine (PM2.5), and inhalable (PM10) particulate matter, ozone (O3) and carbon monoxide (CO) and incident cases of cardiovascular disease (CVD) (n = 2,563) and respiratory disease (n = 1,764) recorded during 2013-2015. Cox regression models with time-dependent covariates were used to estimate adjusted hazard ratios (HRs) for diseases associated with local-level concentrations of AAP exposure, estimated using Bayesian spatio-temporal modelling. RESULTS: The study period of 2013-2015 included a total of 135,199 person-years of follow-up for CVD. There was a positive association of AAP, particularly SO2 and O3, with risk of major cardiovascular and respiratory diseases. Each 10 µg/m3 increase in SO2 was associated with adjusted hazard ratios (HRs) of 1.07 (95% CI: 1.02, 1.12) for CVD, 1.25 (1.08, 1.44) for COPD and 1.12 (1.02, 1.23) for pneumonia. Similarly, each 10 µg/m3 increase in O3 was associated with adjusted HR of 1.02 (1.01, 1.03) for CVD, 1.03 (1.02, 1.05) for all stroke, and 1.04 (1.02, 1.06) for pneumonia. CONCLUSIONS: Among adults in urban China, long-term exposure to ambient air pollution is associated with a higher risk of cardio-respiratory disease.

Long-term solid fuel use and risks of major eye diseases in China: A population-based cohort study of 486,532 adults.

BACKGROUND: Over 3.5 billion individuals worldwide are exposed to household air pollution from solid fuel use. There is limited evidence from cohort studies on associations of solid fuel use with risks of major eye diseases, which cause substantial disease and economic burden globally. METHODS AND FINDINGS: The China Kadoorie Biobank recruited 512,715 adults aged 30 to 79 years from 10 areas across China during 2004 to 2008. Cooking frequency and primary fuel types in the 3 most recent residences were assessed by a questionnaire. During median (IQR) 10.1 (9.2 to 11.1) years of follow-up, electronic linkages to national health insurance databases identified 4,877 incident conjunctiva disorders, 13,408 cataracts, 1,583 disorders of sclera, cornea, iris, and ciliary body (DSCIC), and 1,534 cases of glaucoma. Logistic regression yielded odds ratios (ORs) for each disease associated with long-term use of solid fuels (i.e., coal or wood) compared to clean fuels (i.e., gas or electricity) for cooking, with adjustment for age at baseline, birth cohort, sex, study area, education, occupation, alcohol intake, smoking, environmental tobacco smoke, cookstove ventilation, heating fuel exposure, body mass index, prevalent diabetes, self-reported general health, and length of recall period. After excluding participants with missing or unreliable exposure data, 486,532 participants (mean baseline age 52.0 [SD 10.7] years; 59.1% women) were analysed. Overall, 71% of participants cooked regularly throughout the recall period, of whom 48% used solid fuels consistently. Compared with clean fuel users, solid fuel users had adjusted ORs of 1.32 (1.07 to 1.37, p < 0.001) for conjunctiva disorders, 1.17 (1.08 to 1.26, p < 0.001) for cataracts, 1.35 (1.10 to 1.66, p = 0.0046) for DSCIC, and 0.95 (0.76 to 1.18, p = 0.62) for glaucoma. Switching from solid to clean fuels was associated with smaller elevated risks (over long-term clean fuel users) than nonswitching, with adjusted ORs of 1.21 (1.07 to 1.37, p < 0.001), 1.05 (0.98 to 1.12, p = 0.17), and 1.21 (0.97 to 1.50, p = 0.088) for conjunctiva disorders, cataracts, and DSCIC, respectively. The adjusted ORs for the eye diseases were broadly similar in solid fuel users regardless of ventilation status. The main limitations of this study include the lack of baseline eye disease assessment, the use of self-reported cooking frequency and fuel types for exposure assessment, the risk of bias from delayed diagnosis (particularly for cataracts), and potential residual confounding from unmeasured factors (e.g., sunlight exposure). CONCLUSIONS: Among Chinese adults, long-term solid fuel use for cooking was associated with higher risks of not only conjunctiva disorders but also cataracts and other more severe eye diseases. Switching to clean fuels appeared to mitigate the risks, underscoring the global health importance of promoting universal access to clean fuels.

Association between prenatal depressive symptoms and eczema in infants: The Born in Guangzhou Cohort Study.

BACKGROUND: Eczema is a growing threat on infants' health, and the role of maternal depression in the risk of eczema's early onset is unclear. This study aimed to examine the associations of different exposure timing of prenatal depressive symptoms with offspring's eczema in infancy. METHODS: The study was part of the ongoing prospective Born in Guangzhou Cohort Study. Maternal depressive symptoms were assessed at both early (<20th week of gestation) and late pregnancy (≥33rd week of gestation to delivery) using the Self-Rating Depression Scale. Information on the diagnosis of eczema was collected when the children were 1 year old. Multivariable logistic regression was used to examine the association between prenatal depressive symptoms and infants' eczema and test for moderation by parental history of allergic diseases. RESULTS: In this population, 7.7% (447/5825) of mothers experienced persistent depressive symptoms during pregnancy, 10.1% (590/5825) had depressive symptoms only at early pregnancy, and 8.4% (489/5825) of women experienced depressive symptoms only at late pregnancy. After adjusting for potential confounders, higher risks of eczema were observed in infants of mothers with persistent prenatal depressive symptoms when compared to those children without maternal depressive symptoms throughout pregnancy (OR: 1.55, 95% CI 1.19-2.03). These associations were marginally more pronounced among children in families without parents affected by allergic diseases than in other families (P for interaction = .064 for courses of prenatal depressive symptoms). CONCLUSION: Persistent maternal depressive symptoms during pregnancy increased the risk of infants' eczema, especially in children without family history of allergic diseases. These associations, if proved to be causal, could be an intervention target not only to improve women's health but also to prevent offspring's eczema.

Solid Fuel Use and Risks of Respiratory Diseases. A Cohort Study of 280,000 Chinese Never-Smokers.

RATIONALE: Little evidence from large-scale cohort studies exists about the relationship of solid fuel use with hospitalization and mortality from major respiratory diseases. OBJECTIVES: To examine the associations of solid fuel use and risks of acute and chronic respiratory diseases. METHODS: A cohort study of 277,838 Chinese never-smokers with no prior major chronic diseases at baseline. During 9 years of follow-up, 19,823 first hospitalization episodes or deaths from major respiratory diseases, including 10,553 chronic lower respiratory disease (CLRD), 4,398 chronic obstructive pulmonary disease (COPD), and 7,324 acute lower respiratory infection (ALRI), were recorded. Cox regression yielded adjusted hazard ratios (HRs) for disease risks associated with self-reported primary cooking fuel use. MEASUREMENTS AND MAIN RESULTS: Overall, 91% of participants reported regular cooking, with 52% using solid fuels. Compared with clean fuel users, solid fuel users had an adjusted HR of 1.36 (95% confidence interval, 1.32-1.40) for major respiratory diseases, whereas those who switched from solid to clean fuels had a weaker HR (1.14, 1.10-1.17). The HRs were higher in wood (1.37, 1.33-1.41) than coal users (1.22, 1.15-1.29) and in those with prolonged use (≥40 yr, 1.54, 1.48-1.60; <20 yr, 1.32, 1.26-1.39), but lower among those who used ventilated than nonventilated cookstoves (1.22, 1.19-1.25 vs. 1.29, 1.24-1.35). For CLRD, COPD, and ALRI, the HRs associated with solid fuel use were 1.47 (1.41-1.52), 1.10 (1.03-1.18), and 1.16 (1.09-1.23), respectively. CONCLUSIONS: Among Chinese adults, solid fuel use for cooking was associated with higher risks of major respiratory disease admissions and death, and switching to clean fuels or use of ventilated cookstoves had lower risk than not switching.

Trends in urban/rural inequalities in physical growth among Chinese children over three decades of urbanization in Guangzhou: 1985-2015.

BACKGROUND: Great growth inequalities between urban and rural areas have been reported in China over the past years. By examining urban/rural inequalities in physical growth among children < 7 years old over the past three decades from 1985 to 2015 in Guangzhou, we analyzed altering trends of anthropometric data in children and their association with economic development during the period of rapid urbanization in Guangzhou. METHODS: The height, body weight and nutrition status of children under 7 years old were obtained from two successive cross-sectional surveys and one health surveillance system. Student's t-test, Spearman's rank-order correlation and polynomial regression were used to assess the difference in physical growth between children in urban and rural areas and the association between socioeconomic index and secular growth changes. RESULTS: A height and weight difference was found between urban and rural children aged 0-6 years during the first two decades of our research (1985-2005), which gradually narrowed in both sex groups over time. By the end of 2015, elder boys (age group ≥5 year) and girls (age group ≥4 year) in rural areas were taller than their counterparts in urban areas (p < 0.05).The same trend could be witnessed in the weight of children aged 6 years, with a - 1.30 kg difference (P = 0.03) for boys, and a - 0.05 difference (P = 0.82) for girls. When GDP increased, the gap in boys' weight-for-age z-score (WAZ from 0.25 to 0.01) and height-for-age z-score (HAZ from 0.55 to 0.03) between urban and rural areas diminished, and disappeared when the GDP per capita (USD) approached 25,000. In either urban or rural areas, the urbanization rate and GDP were positively associated with the prevalence of obesity (all R > 0.90 with P < 0.05) and negatively correlated with the prevalence of stunted growth (all R < -0.87 with P < 0.05). CONCLUSION: Growth inequalities gradually decreased with economic development and urbanization, while new challenges such as obesity emerged. To eliminate health problems due to catch-up growth among rural children, comprehensive intervention programs for early child growth should be promoted in rural areas.

Increasing trends in incidence of preterm birth among 2.5 million newborns in Guangzhou, China, 2001 to 2016: an age-period-cohort analysis.

BACKGROUND: The incidence of preterm birth (PTB, < 37 weeks of gestation) has been increasing in China and many other countries in recent years. However, the causes of the increase were not well understood. The current study aims to examine the contribution of maternal age, period of delivery, and maternal birth cohorts to long-term trends in preterm birth in Guangzhou, China. METHODS: In a retrospective population-based study, data were obtained from 2,535,000 singleton live births with 20-43 gestational weeks from 2001 to 2016 and recorded in the Guangzhou Perinatal Health Care and Delivery Surveillance System, in China. The age-period-cohort models were applied to investigate the temporal changes in incidences of PTB, stratified by parity. RESULTS: The incidence of preterm birth steadily increased from 5.1% in 2001 to 5.9% in 2016, with larger rise in primiparous mothers (from 5.0 to 5.9%) compared to multiparous mothers (from 5.6 to 5.9%). A J-shaped and a V-shaped relationship were found between maternal age and PTB among primiparous and multiparous mothers, respectively. A linear cohort effect was found among primiparous mothers with the lowest risk of PTB [risk ratio (RR) = 0.81, 95% confidence interval (CI): 0.74 to 0.89] in 1961 and the highest risk (RR = 1.06, 95% CI: 1.00 to 1.13) in 1997 compared to the mothers born in 1981. An inverse U-shaped association between maternal birth cohort and PTB was found in multiparous mothers. There were weak decreasing period effects on the trend of overall PTB among multiparous mothers and on the trend of extremely (< 27 weeks) or very (28-31 weeks) PTB among both parity groups during the period of 2001-2012. CONCLUSIONS: Our findings showed the PTB incidences had been increasing in the past 16 years in Guangzhou, China and both maternal age and cohort effects contributed to these trends. Further studies are recommended on the impact of altered maternal age and parity on premature births and corresponding public education and public health policies.

Effect of a two-stage intervention package on the cesarean section rate in Guangzhou, China: A before-and-after study.

BACKGROUND: The cesarean section (CS) rate has risen globally during the last two decades. Effective and feasible strategies are needed to reduce it. The aim of this study was to assess the CS rate change after a two-stage intervention package that was designed to reduce the overall CS rate in Guangzhou, China. METHODS AND FINDINGS: This intervention package was implemented by the Health Commission of Guangzhou Municipality in 2 stages (October 2010-September 2014 and October 2014-December 2016) and included programs for population health education, skills training for healthcare professionals, equipment and technical support for local healthcare facilities, and capacity building for the maternal near-miss care system. A retrospective repeated cross-sectional study was conducted to evaluate influences of the intervention on CS rates. A pre-intervention period from January 2008 to September 2010 served as the baseline. The primary outcome was the CS rate, and the secondary outcomes included maternal mortality ratio (MMR) and perinatal mortality rate (PMR), all obtained from the Guangzhou Perinatal Health Care and Delivery Surveillance System (GPHCDSS). The Cochran-Armitage test was used to examine the trends of the overall CS rate, MMR, and PMR across different stages. Segmented linear regression analysis was used to assess the change of the CS rate over the intervention period. A total of 1,921,932 records of births and 108 monthly CS rates from 2008 to 2016 were analyzed. The monthly CS rate declined across the intervention stages (Z = 75.067, p < 0.001), with an average rate of 42.4% at baseline, 39.8% at Stage 1, and 35.0% at Stage 2. The CS rate declined substantially among nulliparous women who delivered term singletons, with an accelerating decreasing trend observed across Stage 1 and Stage 2 (the difference in slopes: -0.09 [95% CI -0.16 to -0.02] between Stage 1 and baseline, p = 0.014; -0.11 [95% CI -0.20 to -0.02] between Stage 1 and Stage 2, p = 0.017). The CS rate in the remaining population increased during baseline and Stage 1 and subsequently decreased during Stage 2. The sensitivity analysis suggested no immediate impact of the universal two-child policy on the trend of the CS rate. The MMR (Z = -4.368, p < 0.001) and PMR (Z = -13.142, p < 0.001) declined by stage over the intervention period. One of the main limitations of the study is the lack of a parallel control group. Moreover, the influence of temporal changes in the study population on the CS rate was unknown. Given the observational nature of the present study, causality cannot be confirmed. CONCLUSIONS: Apparent decline in the overall CS rate was observed in Guangzhou, China, after the implementation of a two-stage intervention package. The decline was most evident among nulliparous women who delivered term singletons. Despite some limitations for causal inference, Guangzhou's experience in controlling the CS rate by implementing composite interventions with public health education and perinatal healthcare service improvement could have implications for other similar areas with high rates of CS.

Factors in Removing Job Restrictions for Cancer Survivors in the United Kingdom Royal Air Force.

Purpose To identify personal, occupational and clinical factors associated with the lifting of restrictions on duties among Royal Air Force (RAF) personnel who have returned to work after surviving primary cancer treatment. Methods A retrospective cohort of 205 RAF personnel aged 18-58 with cancer diagnosed between 2001 and 2011 was followed-up until May 2012. Personal, occupational, and clinical information was extracted from occupational health and primary care records. Predictors of the lifting of (a) employment restrictions on UK duties at 18 months after diagnosis and (b) the lifting of all deployment restrictions at the end of the study were analysed using logistic and Cox regression models. Results At 18 months, 62% of the cancer survivors had restrictions on their UK duties lifted. The positive independent predictors of unrestricted UK duties are testicular cancer (OR 5.34; 95% CI 1.21-23.6) and no treatment being required (16.8; 1.11-255.2). The lifting of all employment restrictions and return to full deployability was achieved by 41% of the participants (median time 2.1 years), with testicular cancer (HR 2.69; 95% CI 1.38-5.26) and age at diagnosis (1.05; 1.01-1.09) being the positive independent predictors of faster lifting of all restrictions. Conclusion Diagnostic group, prognosis and type of treatment are not the only predictor of employment outcome after cancer. Patient-centred factors such as smoking, age, fatigue, job status, job type and length of employment are also important predictors of return to pre-morbid job function in cancer survivors in the RAF.

Cardiorespiratory health effects of gaseous ambient air pollution exposure in low and middle income countries: a systematic review and meta-analysis.

BACKGROUND: Lack of research on the effects of gaseous pollutants (nitrogen oxides [NOx], sulfur dioxide [SO2], carbon monoxide [CO] and ozone [O3]) in the ambient environment on health outcomes from within low and middle income countries (LMICs) is leading to reliance on results from studies performed within high income countries (HICs). This systematic review and meta-analysis examines the cardiorespiratory health effects of gaseous pollutants in LMICs exclusively. METHODS: Systematic searching was carried out and estimates pooled by pollutant, lag and outcome, and presented as excess relative risk per 10 µg/m3 (NOx, SO2, O3) or 1 ppm (CO) increase pollutant. Sub-group analysis was performed examining estimates by specific outcomes, city and co-pollutant adjustment. RESULTS: Sixty studies met the inclusion criteria, most (44) from the East Asia and Pacific region. A 10 µg/m3 increase in same day NOx was associated with 0.92% (95% CI: 0.44, 1.39), and 0.70% (0.01, 1.40) increases in cardiovascular and respiratory mortality respectively, same day NOx was not associated with morbidity. Same day sulfur dioxide was associated with 0.73% (0.04, 1.42) and 0.50% (0.01, 1.00) increases in respiratory morbidity and in cardiovascular mortality respectively. CONCLUSIONS: Acute exposure to gaseous ambient air pollution (AAP) is associated with increases in morbidity and mortality in LMICs, with greatest associations observed for cardiorespiratory mortality.

Early life vitamin D status and asthma and wheeze: a systematic review and meta-analysis.

BACKGROUND: Vitamin D deficiency has been linked to an increased risk of asthma. This study aimed to quantify the effect of early life vitamin D status on asthma and wheeze later in life. METHODS: PubMed, Embase, CINAHL, and CNKI databases, the Cochrane Central Register of Controlled Trials, and Google Scholar were searched up to July 2017. We included randomized controlled trials (RCTs) and cohort studies with vitamin D level in blood (maternal or cord or infant) or intake (maternal intake during pregnancy or infant intake) and asthma and/or wheeze. Two reviewers independently extracted data. Fixed- and random-effects models were used to summarize the risk estimates of comparisons between highest vs. lowest vitamin D categories. RESULTS: Of the 1485 studies identified, three RCTs and 33 cohort studies were included. We did not include the RCTs (1619 participants) in the meta-analysis as the comparators and outcome definitions were heterogenous. Three RCTs reported a non-statistically significant effect of vitamin D supplementation during pregnancy on offspring wheeze/asthma at 3 years of age. Pooled estimates of cohort studies suggest no association between antenatal blood vitamin D levels or vitamin D intake and offspring asthma assessed either > 5 years or ≤ 5 years. The estimate for blood vitamin D remained unchanged when two studies assessing asthma in adulthood were excluded, but a significant inverse association emerged between vitamin D intake and childhood asthma. We found no association between antenatal vitamin D level and wheeze. On the other hand, vitamin D intake during pregnancy may have a protective effect against wheeze. CONCLUSIONS: The pooled estimates from cohort studies show no association between antenatal blood vitamin D level and asthma/wheeze in later life. Whereas, the pooled estimates from cohort studies suggest that antenatal vitamin D intake may have an effect on childhood asthma > 5 years or childhood wheeze. The inconsistent results from studies assessing vitamin D either in blood or intake may be explained by previously reported non-linear association between blood vitamin D3 and childhood asthma. Further trials with enough power and longer follow-up time should be conducted to confirm the results.

Association of Solid Fuel Use With Risk of Cardiovascular and All-Cause Mortality in Rural China.

Importance: When combusted indoors, solid fuels generate a large amount of pollutants such as fine particulate matter. Objective: To assess the associations of solid fuel use for cooking and heating with cardiovascular and all-cause mortality. Design, Setting, and Participants: This nationwide prospective cohort study recruited participants from 5 rural areas across China between June 2004 and July 2008; mortality follow-up was until January 1, 2014. A total of 271 217 adults without a self-reported history of physician-diagnosed cardiovascular disease at baseline were included, with a random subset (n = 10 892) participating in a resurvey after a mean interval of 2.7 years. Exposures: Self-reported primary cooking and heating fuels (solid: coal, wood, or charcoal; clean: gas, electricity, or central heating), switching of fuel type before baseline, and use of ventilated cookstoves. Main Outcomes and Measures: Death from cardiovascular and all causes, collected through established death registries. Results: Among the 271 217 participants, the mean (SD) age was 51.0 (10.2) years, and 59% (n = 158 914) were women. A total of 66% (n = 179 952) of the participants reported regular cooking (at least weekly) and 60% (n = 163 882) reported winter heating, of whom 84% (n = 150 992) and 90% (n = 147 272) used solid fuels, respectively. There were 15 468 deaths, including 5519 from cardiovascular causes, documented during a mean (SD) of 7.2 (1.4) years of follow-up. Use of solid fuels for cooking was associated with greater risk of cardiovascular mortality (absolute rate difference [ARD] per 100 000 person-years, 135 [95% CI, 77-193]; hazard ratio [HR], 1.20 [95% CI, 1.02-1.41]) and all-cause mortality (ARD, 338 [95% CI, 249-427]; HR, 1.11 [95% CI, 1.03-1.20]). Use of solid fuels for heating was also associated with greater risk of cardiovascular mortality (ARD, 175 [95% CI, 118-231]; HR, 1.29 [95% CI, 1.06-1.55]) and all-cause mortality (ARD, 392 [95% CI, 297-487]; HR, 1.14 [95% CI, 1.03-1.26]). Compared with persistent solid fuel users, participants who reported having previously switched from solid to clean fuels for cooking had a lower risk of cardiovascular mortality (ARD, 138 [95% CI, 71-205]; HR, 0.83 [95% CI, 0.69-0.99]) and all-cause mortality (ARD, 407 [95% CI, 317-497]; HR, 0.87 [95% CI, 0.79-0.95]), while for heating, the ARDs were 193 (95% CI, 128-258) and 492 (95% CI, 383-601), and the HRs were 0.57 (95% CI, 0.42-0.77) and 0.67 (95% CI, 0.57-0.79), respectively. Among solid fuel users, use of ventilated cookstoves was also associated with lower risk of cardiovascular mortality (ARD, 33 [95% CI, -9 to 75]; HR, 0.89 [95% CI, 0.80-0.99]) and all-cause mortality (ARD, 87 [95% CI, 20-153]; HR, 0.91 [95% CI, 0.85-0.96]). Conclusions and Relevance: In rural China, solid fuel use for cooking and heating was associated with higher risks of cardiovascular and all-cause mortality. These risks may be lower among those who had previously switched to clean fuels and those who used ventilation.

The Born in Guangzhou Cohort Study (BIGCS).

The Born in Guangzhou Cohort Study (BIGCS) is a large-scale prospective observational study investigating the role of social, biological and environmental influences on pregnancy and child health and development in an urban setting in southern China. Pregnant women who reside in Guangzhou and who attend Guangzhou Women and Children's Medical Center (GWCMC) for antenatal care in early pregnancy (<20 weeks' gestation) are eligible for inclusion. Study recruitment commenced in February 2012, with an overall participation rate of 76.3%. Study recruitment will continue until December 2018 to achieve the target sample size of 30,000 mother-child pairs. At 30 April 2016, a total of 75,422 questionnaires have been collected, while 14,696 live births have occurred with planned follow-up of cohort children until age 18 years. During the same period a total of 1,053,000 biological samples have been collected from participants, including maternal, paternal and infant blood, cord blood, placenta, umbilical cord, and maternal and infant stool samples. The dataset has been enhanced by record linkage to routine health and administrative records. We plan future record linkage to school enrolment and national examination records.

Does tea consumption during early pregnancy have an adverse effect on birth outcomes?

BACKGROUND: Tea, a common beverage, has been suggested to exhibit a number of health benefits. However, one of its active ingredients, caffeine, has been associated with preterm birth and low birthweight. We investigated whether tea consumption during early pregnancy is associated with an increased risk of preterm birth and abnormal fetal growth. METHODS: A total of 8775 pregnant women were included from the Born in Guangzhou Cohort Study. Tea consumption (type, frequency, and strength) during their first trimester and social and demographic factors were obtained by way of questionnaires administered during pregnancy. Information on birth outcomes and complications during pregnancy was obtained from hospital medical records. RESULTS: Overall habitual tea drinking (≥1 serving/week) prevalence among pregnant women was low, at 16%. After adjustment for potential confounding factors (eg, maternal age, educational level, monthly income) tea drinking during early pregnancy was not associated with an increased risk of preterm birth or abnormal fetal growth (small or large for gestational age) (P>.05). CONCLUSIONS: We did not identify a consistent association between frequency of tea consumption or tea strength and adverse birth outcomes among Chinese pregnant women with low tea consumption. Our findings suggest that occasional tea drinking during pregnancy is not associated with increased risk of preterm birth or abnormal fetal growth. Given the high overall number of annual births in China, our findings have important public health significance.

Predictors of return to work in cancer survivors in the Royal Air Force.

PURPOSE: Return to work (RTW) is beneficial for cancer survivors, employers and society. However, little is known about predictors of RTW in the military environment. METHODS: A cohort of 194 Royal Air Force (RAF) personnel aged 18-58 who survived primary cancer treatment between 2001 and 2011 were followed up for 18 months. Information was obtained from occupational health and primary care records. Personal, occupational and clinical predictors of RTW were identified by Cox proportional hazards regression. RESULTS: The median sickness absence before RTW was 107 days. Six months after diagnosis 54 % of participants had RTW, and reached 80 % by 12 months. Time taken to RTW was predicted by age at diagnosis, rank, trade group, pre-diagnosis sickness absence, site of cancer, treatment modality, and prognosis. RTW at 18 months were predicted by higher rank (HR = 2.31; 95 % CI 1.46-3.65), and having melanoma (9.75; 4.97-19.13). Those receiving chemotherapy were significantly less likely to have RTW compared to other treatment modalities (0.18; 0.10-0.32). CONCLUSIONS: Rank, cancer diagnostic group, and treatment modality are the most important predictors of RTW in cancer survivors in the RAF. These predictors can be used to inform rehabilitation programmes and decisions on RTW.

The effect of exposure to biomass smoke on respiratory symptoms in adult rural and urban Nepalese populations.

BACKGROUND: Half of the world's population is exposed to household air pollution from biomass burning. This study aimed to assess the relationship between respiratory symptoms and biomass smoke exposure in rural and urban Nepal. METHODS: A cross-sectional study of adults (16+ years) in a rural population (n = 846) exposed to biomass smoke and a non-exposed urban population (n = 802) in Nepal. A validated questionnaire was used along with measures of indoor air quality (PM2.5 and CO) and outdoor PM2.5. RESULTS: Both men and women exposed to biomass smoke reported more respiratory symptoms compared to those exposed to clean fuel. Women exposed to biomass were more likely to complain of ever wheeze (32.0 % vs. 23.5%; p = 0.004) and breathlessness (17.8% vs. 12.0%, p = 0.017) compared to males with tobacco smoking being a major risk factor. Chronic cough was similar in both the biomass and non-biomass smoke exposed groups whereas chronic phlegm was reported less frequently by participants exposed to biomass smoke. Higher PM2.5 levels (≥2 SDs of the 24-hour mean) were associated with breathlessness (OR = 2.10, 95% CI 1.47, 2.99) and wheeze (1.76, 1.37, 2.26). CONCLUSIONS: The study suggests that while those exposed to biomass smoke had higher prevalence of respiratory symptoms, urban dwellers (who were exposed to higher ambient air pollution) were more at risk of having productive cough.

Modelling personal temperature exposure using household and outdoor temperature and questionnaire data: Implications for epidemiological studies.

Non-optimal temperature is a leading risk factor for global disease burden. Most epidemiological studies assessed only outdoor temperature, with important uncertainties on personal exposure misclassification. The CKB-Air study measured personal, household (kitchen and living room), and outdoor temperatures in the summer (MAY-SEP 2017) and winter (NOV 2017-JAN 2018) in 477 participants in China. After data cleaning, ∼88,000 person-hours of data were recorded across each microenvironment. Using multivariable linear regression (MLR) and random forest (RF) models, we identified key predictors and constructed personal temperature exposure prediction models. We used generalised additive mixed effect models to examine the relationships of personal and outdoor temperatures with heart rate. The 24-hour mean (SD) personal and outdoor temperatures were 29.2 (3.8) °C and 27.6 (6.4) °C in summer, and 12.0 (4.0) °C and 7.5 (4.2) °C in winter, respectively. The temperatures across microenvironments were strongly correlated (Spearman's ρ: 0.86-0.92) in summer. In winter, personal temperature was strongly related to household temperatures (ρ: 0.74-0.79) but poorly related to outdoor temperature (ρ: 0.30). RF algorithm identified household and outdoor temperatures and study date as top predictors of personal temperature exposure for both seasons, and heating-related factors were important in winter. The final MLR and RF models incorporating questionnaire and device data performed satisfactorily in predicting personal exposure in both seasons (R2summer: 0.92; R2winter: 0.68-0.70). We found consistent U-shaped associations between measured and predicted personal temperature exposures and heart rate (lowest at âˆ¼ 14.5 °C), but a weak positive linear association with outdoor temperature. Personal and outdoor temperatures differ substantially winter, but prediction models incorporating household and outdoor temperatures and questionnaire data performed satisfactorily. Exposure misclassification from using outdoor temperature may produce inappropriate epidemiological findings.

Reduced lung function due to biomass smoke exposure in young adults in rural Nepal.

This study aimed to assess the effects of biomass smoke exposure on lung function in a Nepalese population, addressing some of the methodological issues seen in previous studies. We carried out a cross-sectional study of adults in a population exposed to biomass smoke and a non-exposed population in Nepal. Questionnaire and lung function data were acquired along with direct measures of indoor and outdoor air quality. Ventilatory function (forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC) and forced expiratory flow at 25-75% of FVC) was significantly reduced in the population using biomass across all age groups compared to the non-biomass-using population, even in the youngest (16-25 yrs) age group (mean FEV(1) (95% CI) 2.65 (2.57-2.73) versus 2.83 (2.74-2.91) L; p=0.004). Airflow obstruction was twice as common among biomass users compared with liquefied petroleum gas users (8.1% versus 3.6%; p<0.001), with similar patterns for males (7.4% versus 3.3%; p=0.022) and females (10.8% versus 3.8%; p<0.001), based on the lower limit of normal. Smoking was a major risk factor for airflow obstruction, but biomass exposure added to the risk. Exposure to biomass smoke is associated with deficits in lung function, an effect that can be detected as early as the late teenage years. Biomass smoke and cigarette smoke have additive adverse effects on airflow obstruction in this setting.