Relationship of night and shift work with weight change and lifestyle behaviors.

OBJECTIVE: To prospectively study the association of night and shift work with weight change and lifestyle behaviors. METHODS: Workers participating in the Netherlands Working Conditions Cohort Study (2008 and 2009) (N = 5951) reported night and shift work, weight and height. Groups included stable night or shift work, from day work to night or shift work, from night or shift work to day work, and no night or shift work in 2008 and 2009. Regression analyses were used to study association changes in night and shift work with weight change and changes in lifestyle behaviors. RESULTS: A larger weight change was seen in normal-weight workers changing from day to shift work (ß = 0.93%; 95% confidence interval, 0.01 to 1.85) compared with stable no shift workers. No further associations of night and shift work with weight change were observed, neither in normal-weight, overweight, and obese workers. CONCLUSIONS: Despite the fact that starting night or shift work is associated with some unhealthy lifestyle habits, this study did not confirm a positive association of night and shift work with weight change over 1 year, except for normal-weight workers moving from day to shift work.

Time in bed, sleep quality and associations with cardiometabolic markers in children: the Prevention and Incidence of Asthma and Mite Allergy birth cohort study.

We investigated associations of time in bed and multiple sleep quality characteristics with cardiometabolic markers in children. Data from the prevention and incidence of asthma and mite allergy study, a population-based prospective birth-cohort study started in 1996-1997 in the Netherlands, were analysed. In total 1481 children aged 11-12 years completed a questionnaire (including questions on sleep) and underwent a medical examination. We measured body mass index, waist circumference, total- and high-density lipoprotein cholesterol, blood pressure and glycated haemoglobin. Results showed that in girls, some sleep characteristics were related to anthropometrics (body mass index, waist circumference) and cholesterol. Girls who had a long time in bed (11-12.5 h) had 0.16 lower body mass index z-score (95% confidence interval -0.31; -0.01) and 0.99 cm smaller waist circumference (95% confidence interval -2.01; -0.13) compared with girls who spent 10-10.5 h in bed. Girls who went to bed late and rose early had 0.16 mm higher total cholesterol (95% confidence interval 0.01; 0.31) and 0.08 mm higher high-density lipoprotein cholesterol (95% confidence interval 0.01; 0.14) than 'early to bed/early rise' girls. Girls with night-time awakenings had 0.14 mm higher total cholesterol (95% confidence interval 0.03; 0.25) than girls without night-time awakenings. Girls who felt sleepy/tired ≥1 day per week had 0.10 mm lower high-density lipoprotein cholesterol (95% confidence interval -0.16; -0.04) and 0.17 mm higher total cholesterol/high-density lipoprotein cholesterol ratio (95% confidence interval 0.02; 0.32) than girls who did not feel sleepy. No associations were found for boys. Sleep characteristics were not related to blood pressure and glycated haemoglobin, and effect sizes of the associations in girls were small. Therefore, we consider it premature to propose that improved sleep could reduce cardiovascular risk during childhood.

The association between indoor temperature and body mass index in children: the PIAMA birth cohort study.

BACKGROUND: Several experimental studies showed consistent evidence for decreased energy expenditure at higher ambient temperatures. Based on this, an association between thermal exposure and body weight may be expected. However, the effect of thermal exposure on body weight has hardly been studied. Therefore, this study investigated the association between indoor temperature and body mass index (BMI) in children in real life. METHODS: This longitudinal observational study included 3 963 children from the Dutch Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort that started in 1996. These children were followed from birth until the age of 11 years. Winter indoor temperature (living room and bedroom) was reported at baseline and BMI z-scores were available at 10 consecutive ages. Missing data were multiply imputed. Associations between indoor temperature and BMI were analyzed using generalized estimating equations (GEE), adjusted for confounders and stratified by gender. In a subgroup of 104 children, bedroom temperature was also measured with data loggers. RESULTS: Mean reported living room and bedroom temperature were 20.3°C and 17.4°C, respectively. Reported and measured bedroom temperatures were positively correlated (r = 0.42, p = 0.001).Neither reported living room temperature (-0.03 ≤ ß ≥ 0.04) and bedroom temperature (-0.01 ≤ ß ≥ 0.02) nor measured bedroom temperature (-0.04 ≤ ß ≥ 0.05) were associated with BMI z-score between the age of 3 months and 11 years. CONCLUSIONS: This study in children did not support the hypothesized association between indoor temperature and BMI in a real life setting.

Waist circumference, BMI, and lung function in 8-year-old children: the PIAMA birth cohort study.

BACKGROUND: Body mass index (BMI) and waist circumference (WC) may be associated with lung function in children, as observed in adults. METHODS: Height, weight, waist circumference, and lung function (FVC and FEV1 ) were measured during a medical examination in 1,058 eight-year-old children participating in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort study. RESULTS: After adjusting for height, age and other potential confounders large WC or high BMI (>90th percentile) were not associated with forced expiratory volume in 1 sec (FEV1) or forced vital capacity (FVC). In girls only, large WC was, independently of BMI, associated with 3.5% (95% confidence interval (CI): -6.4, -0.6) lower FEV1 /FVC ratio in the model including WC and BMI. Girls with low BMI (<10th percentile) had 4.6% lower FEV1 (95% CI: -8.4, -0.6) and 5.1% lower FVC (95% CI: -8.8, -1.2) than girls with normal BMI. In boys, we did not observe associations between low or high BMI and lung function independent of WC, or between small or large WC and lung function after adjustment for BMI. CONCLUSION: At 8 years of age, a high BMI or large WC are not yet associated with FEV1 and FVC, indicating that this association may change over the course of life from childhood to adulthood.

BMI and waist circumference; cross-sectional and prospective associations with blood pressure and cholesterol in 12-year-olds.

OBJECTIVE: Childhood and adolescent overweight, defined by body mass index (BMI) are associated with an increased risk of cardiovascular disease in later life. Abdominal adiposity may be more important in associations with cardiovascular diseases but waist circumference (WC) has been rarely studied in children. We studied associations between BMI and WC and blood pressure (BP) and cholesterol in 12-year-old children and prospectively changes in BMI or WC status between age 8 and 12 years and BP and cholesterol at age 12. STUDY DESIGN: Weight, height, WC, BP and cholesterol concentrations were measured in 1432 children at age 12 years. Linear regression was used to study the associations between high BMI and large WC (>90(th) percentile) and BP and cholesterol. RESULTS: Systolic BP was 4.9 mmHg higher (95% (CI 2.5, 7.2) in girls and 4.2 mmHg (95%CI 1.9, 6.5) in boys with a high BMI. Large WC was also associated with higher systolic BP in girls (3.7 mmHg (95%CI 1.3, 6.1)) and boys (3.5 mmHg (95%CI 1.2, 5.8)). Diastolic BP and cholesterol concentrations were significantly positively (HDL cholesterol negatively) associated with high BMI and large WC, too. Normal weight children with a history of overweight did not have higher blood pressure levels or adverse cholesterol concentrations than children that were normal weight at both ages. CONCLUSION: A high BMI and large WC were associated with higher BP levels and adverse cholesterol concentrations. WC should be taken into account when examining cardiovascular risk factors in children.

Maternal use of folic acid supplements during pregnancy, and childhood respiratory health and atopy.

Previous studies have suggested possible adverse side-effects of maternal use of folic acid-containing supplements (FACSs) during pregnancy on wheeze and asthma in early childhood. We investigated the association between maternal use of FACSs and childhood respiratory health and atopy in the first 8 yrs of life. Data on maternal use of FACSs, collected during pregnancy, were available for 3,786 children participating in the Prevention and Incidence of Asthma and Mite Allergy birth cohort study. Questionnaire data on children's respiratory and allergic symptoms were collected annually and allergic sensitisation and bronchial hyperresponsiveness (BHR) were measured at 8 yrs of age. No overall (from 1 to 8 yrs of age) associations were observed between maternal use of FACSs and (frequent) asthma symptoms, wheeze, lower respiratory tract infection, frequent respiratory tract infection and eczema. Maternal folic acid use was associated with wheeze at 1 yr of age (prevalence ratio 1.20, 95% CI 1.04-1.39), but not with wheeze at later ages. Pre-natal exposure to FACSs was not associated with sensitisation and BHR. Apart from a small increased risk of early wheeze, we observed no adverse respiratory or allergic outcomes associated with pre-natal FACSs exposure in our study population.

Early-life determinants of total and HDL cholesterol concentrations in 8-year-old children; the PIAMA birth cohort study.

BACKGROUND: Adult cholesterol concentrations might be influenced by early-life factors, such as breastfeeding and birth weight, referred to as "early programming". How such early factors exert their influence over the life course is still poorly understood. Evidence from studies in children and adolescents is scarce and conflicting. We investigated the influence of 6 different perinatal risk factors on childhood total and HDL cholesterol concentrations and total-to-HDL cholesterol ratio measured at 8 years of age, and additionally we studied the role of the child's current Body Mass Index (BMI). METHODS: Anthropometric measures and blood plasma samples were collected during a medical examination in 751 8-year-old children participating in the prospective Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort study. Linear and logistic regression were performed to estimate associations of total and HDL cholesterol concentrations with breastfeeding, birth weight, infant weight gain, maternal overweight before pregnancy, gestational diabetes and maternal smoking during pregnancy, taking into account the child's current BMI. RESULTS: Linear regressions showed an association between total-to-HDL cholesterol ratio and maternal pre-pregnancy overweight (ß = 0.15, Confidence Interval 95% (CI): 0.02, 0.28), rapid infant weight gain (ß = 0.13, 95%CI: 0.01, 0.26), and maternal smoking during pregnancy (ß = 0.14, 95%CI: 0.00, 0.29). These associations were partly mediated by the child's BMI. CONCLUSION: Total-to-HDL cholesterol ratio in 8-year-old children was positively associated with maternal pre-pregnancy overweight, maternal smoking during pregnancy and rapid infant weight gain.

Parental reported compared with measured waist circumference in 8-year-old children.

OBJECTIVE: Most epidemiological, questionnaire-based studies collect data on body weight and height but not on waist circumference (WC), although WC is suggested to be clinically more relevant. It is unknown whether valid WC data of school-aged children can be obtained by questionnaires. In this study the agreement between parental reported and measured WC in 8-year-old children was investigated and compared with the agreement between parental reported and measured body mass index (BMI). METHODS: Data on body weight, height, and WC of 1 292 8-year-old Dutch children were collected by a medical examination and a questionnaire. Mean differences, correlations and misclassification based on parental reported values were calculated. RESULTS: Mean differences between parental reported and measured values were small. Pearson correlation coefficient for measured and reported WC was 0.83 compared with 0.90 for measured and reported BMI. Parents of children with a high BMI tended to underreport their child's WC and body weight. A total of 22.7% of overweight children were misclassified as being normal weight based on reported WC compared with measured WC. For BMI this applied to 23.7% of children. CONCLUSION: Parental reported waist circumference corresponded well with measured values, indicating that reported waist circumference can be used to study associations between waist circumference and risk factors or health outcomes.