Mathieu Roelants

References for growth and pubertal development from birth to 21 years in Flanders, Belgium

Background: Due to the secular trend in length and height, growth references need to be updated regularly. Reference charts that were until recently used in Belgium are based on samples collected more than 30 years ago, and references for body mass index (BMI) and pubertal development have not been established before. Aims: To establish contemporary cross-sectional reference charts for height, weight, BMI, head circumference, and pubertal development from birth to 21 years of age, based on a representative sample of children from Flanders, Belgium. Subjects and methods: 15 989 healthy subjects of Belgian origin, 0–25 years of age, were measured in 2002–2004. Growth curves were fitted with the LMS method, and percentiles for the pubertal development were estimated with generalized additive models on status quo data from 8690 subjects aged 6–22 years of age. Results: A positive secular trend in height and weight is observed in children above 5 years of age. Adult median height has increased by 1.2 cm/decade in boys and 0.8 cm/decade in girls; median weight by 0.9 kg/decade in boys, and 1.0 kg/decade in girls, and the weight distribution became more skewed. The BMI curve is comparable to that of other populations, except for higher percentiles. This reflects the increasing prevalence of overweight and obesity. Median age at menarche (13.0 years) has not advanced any more over the past 50 years. Median ages at menarche and B2 in girls and G2 or T4 in boys are comparable to other West European estimates, but approximately 10% enter G2/T4 before 9 years of age. Conclusions: The ongoing secular trend in height and weight makes growth charts previously used in Belgium obsolete. New representative charts for growth and pubertal development are introduced. For weight monitoring, it is advised that the now-available BMI growth charts are used.

Overweight and obesity in Norwegian children: prevalence and socio-demographic risk factors

Aim:  The aim of this study was to estimate the prevalence of childhood overweight and obesity and to identify socio‐demographic risk factors in Norwegian children.

The Effects of GSTM1 and GSTT1 Polymorphisms on Micronucleus Frequencies in Human Lymphocytes In vivo

The influence of genetic polymorphisms in GSTM1 and GSTT1 genes on micronucleus frequencies in human peripheral blood lymphocytes was assessed through a pooled analysis of data from seven laboratories that did biomonitoring studies using the in vivo cytokinesis-block micronucleus assay. A total of 301 nonoccupationally exposed individuals (207 males and 94 females) and 343 workers (237 males and 106 females) occupationally exposed to known or suspected genotoxic substances were analyzed by Poisson regression. The results of the pooled analysis indicate that the GSTT1 null subjects had lower micronucleus frequencies than their positive counterparts in the total population (frequency ratio, 0.55; 95% confidence interval, 0.33-0.89). The protective effect of this genotype is reversed with increasing age, with a frequency ratio of 1.33 (95% confidence interval, 1.06-1.68) in subjects aged 60 years. A significant overall increase in micronucleus frequency with age and gender (P < 0.001 and P = 0.024, respectively) was observed, females having higher micronucleus frequencies than males, when occupationally exposed (P = 0.002). Nonoccupationally exposed smokers had lower micronucleus frequencies than nonsmokers (P = 0.001), whereas no significant difference in micronucleus level was observed between smokers and nonsmokers in the occupationally exposed group (P = 0.79). This study confirms that pooled analyses, by increasing the statistical power, are adequate for assessing the involvement of genetic variants on genome stability and for resolving discrepancies among individual studies. (Cancer Epidemiol Biomarkers Prev 2006;15(5):1038–42)

Growth of Belgian and Norwegian children compared to the WHO growth standards: prevalence below −2 and above +2 SD and the effect of breastfeeding

Background New national growth references have been published in Belgium and Norway. The WHO recommends universal use of their 2006 Child Growth Standards based on data from breastfed children. Objective To compare the growth of Belgian and Norwegian children with the WHO standards. Participants 6985 children 0–5 years of age from Belgium and Norway. Design Proportion of children below −2 SD and above +2 SD of the WHO standards was calculated for length/height, weight, body mass index and head circumference. Average SD scores of exclusively breastfed children of non-smoking mothers were compared with national reference data and with the WHO standards. Results Generally, the number of Belgian and Norwegian children below −2 SD lines of the WHO standards was lower and above +2 SD higher than expected. The largest differences were for head circumference (0.97% Belgian and 0.18% Norwegian children below −2 SD, 6.55% Belgian and 6.40% Norwegian children above +2 SD) and the smallest for length/height (1.25% Belgian and 1.43% Norwegian children below −2 SD, 3.47% Belgian and 2.81% Norwegian children above +2 SD). The growth pattern of breastfed children of non-smoking mothers was in both countries more alike the local national growth references than the WHO standards. Conclusions There are significant deviations in the proportion of children outside normal limits (±2 SD) of the WHO standards. This was true for all children, including those who were exclusively breastfed. Hence, adoption of the WHO growth charts could have consequences for clinical decision-making. These findings advocate the use of national references in Belgium and Norway, also for breastfed children.

Exploring the aneugenic and clastogenic potential in the nanosize range: A549 human lung carcinoma cells and amorphous monodisperse silica nanoparticles as models

Abstract We explored how to assess the genotoxic potential of nanosize particles with a well validated assay, the in vitro cytochalasin-B micronucleus assay, detecting both clastogens and aneugens. Monodisperse Stöber amorphous silica nanoparticles (SNPs) of three different sizes (16, 60 and 104 nm) and A549 lung carcinoma cells were selected as models. Cellular uptake of silica was monitored by ICP-MS. At non-cytotoxic doses the smallest particles showed a slightly higher fold induction of micronuclei (MNBN). When considering the three SNPs together, particle number and total surface area appeared to account for MNBN induction as they both correlated significantly with the amplitude of the effect. Using nominal or cellular dose did not show statistically significant differences. Likewise, alkaline comet assay and FISH-centromeric probing of MNBN indicated a weak and not statistically significant induction of oxidative DNA damage, chromosome breakage and chromosome loss. This line of investigation will contribute to adequately design and interpret nanogenotoxicity assays.

Growth references for Norwegian children

BACKGROUND The growth charts currently used in Norway, are based on measurements from the 1970s and 80s. New data are available from the Bergen Growth Study collected in 2003 - 6. In 2006, WHO published international charts for 0-5 year-old children. MATERIAL AND METHODS New growth charts based on data from the Bergen Growth Study and the Medical Birth Registry of Norway are presented for children aged 0-19 years. These were compared with existing references and with the WHO curves. RESULTS Norwegian children aged 0-4 years have length, height and weight measurements that are only marginally different from those in the Norwegian growth charts in current use. In older children there has been an increase in the 50-percentile for height up to 3.4 cm in boys and 2.5 cm in girls. For children older than four years, weight for height has increased, especially for the upper percentiles. The percentile lines in the new Norwegian reference are generally positioned above the WHO standard for weight at birth, and for length/height, weight and head circumference in the age group 6 months to 5 years. INTERPRETATION The secular trends in growth mirror the need for new charts. The fact that Norwegian children differ from the WHO standards may reflect population differences relating to environment or growth potential between the populations.

Overweight and obesity in Norwegian children: Secular trends in weight‐for‐height and skinfolds

Aim: The prevalence of overweight and obesity in paediatric populations has been rapidly increasing in many countries over the past decades. The aims of the present study were to provide new data on weight‐for‐height and skinfolds, and to compare these to growth references for children between 3 and 17 years, collected in the same city between 1971 and 1974.

Growth references for 0–19 year-old Norwegian children for length/height, weight, body mass index and head circumference

Background: Previous growth references for Norwegian children were based on measurements from the 1970s and 1980s. New reference data, collected through the Bergen Growth Study and the Medical Birth Registry of Norway, are presented as LMS values. Materials and methods: A cross-sectional sample of children aged 0–19 years in stratified randomized design measured in 2003–2006 as a part of the Bergen Growth Study (n = 7291) and birth data of children born in 1999–2003 from the Medical Birth Registry of Norway (n = 12 576) was used to estimate the new references by the means of the LMS method. Measurement reliability was assessed by test-rest studies. Results: New references were constructed for length/height, weight, body mass index (BMI) and head circumference. Length/height and weight for children aged 0–4 years were similar to previous Norwegian references, but mean height increased up to a maximum of 3.4 cm in boys and 2.5 cm in girls during the pubertal years. Mean height was similar to (or slightly higher) in comparison with other recent European references. Reliability of the measurements compared well with published estimates. Conclusion: Because of the observed secular trends in growth, it is advised to use the new references, which have been endorsed by the Norwegian Department of Health.

Vaccination coverage in 14-year-old adolescents: documentation, timeliness, and sociodemographic determinants.

OBJECTIVE. The objective of this study was to measure the coverage and influencing determinants of hepatitis B virus, measles-mumps-rubella, and Meningococcus serogroup C vaccination in 14-year-old adolescents in Flanders, Belgium, in 2005. METHODS. A total of 1500 adolescents who were born in 1991 and were living in Flanders were selected with a 2-stage cluster sampling technique. Home visits to copy vaccination documents and complete a questionnaire on sociodemographic and other related factors were conducted by trained interviewers. Only documented vaccination dates were accepted. Missing data were, when possible, retrieved through medical charts of the School Health System. RESULTS. For 1344 (89.6%) adolescents, a home visit was performed. Vaccination coverage was 75.7% for the third dose of hepatitis B virus, 80.6% for the first dose and 83.6% for the second dose of measles-mumps-rubella, and 79.8% for Meningococcus serogroup C. Only 74.6% of the adolescents had proof of 2 measles-mumps-rubella vaccines. Although 1006 (74.8%) adolescents had vaccination data available at home at the time of the interview, only 427 (31.8%) were able to show written proof of all studied vaccines. The probably underestimated coverage rates are well below World Health Organization recommendations, but timeliness of vaccinations was respected. Univariate logistic regression showed that unemployment of the father as proxy measure of socioeconomic status was detrimental for vaccination status, in contrast to partial employment of the mother, which was a favorable factor. Previously unreported determinants of lower coverage rates inferred from this study are single divorced parents, larger families (≥4 children), lower adolescent educational level, enrollment in special education, and repeating a grade. CONCLUSIONS. Insufficient documentation is a major barrier in this vaccination coverage study. More attention should go to those with the lowest coverage rates, such as adolescents from large families, with separated parents, and with a lower socioeconomic background.

Are ICSI adolescents at risk for increased adiposity

BACKGROUND Puberty is a critical period for the development of cardio-metabolic disturbances, including a more central body fat distribution. It is still unclear if IVF and more specifically ICSI, can permanently and detrimentally affect body fat accumulation in the human offspring. Therefore, adiposity and body fat distribution in 14-year-old adolescents born after ICSI were investigated. METHODS Body composition data, including anthropometry (weight, height and BMI), skinfold thicknesses (peripheral: triceps and biceps skinfolds; central: supra-iliacal and subscapular skinfolds; total: sum of the four skinfolds) and circumferences (waist, mid-upper arm) were compared between 217 ICSI singletons (116 boys, 101 girls) and 223 singletons (115 boys, 108 girls) born after spontaneous conception (SC). ICSI teenagers were part of a previously published ICSI cohort followed since birth; SC controls were recruited from schools in the surroundings. RESULTS Among all boys, no differences in body composition measurements were found between the ICSI and SC group, taking into account confounding variables. In boys with more advanced pubertal stages, a significantly higher sum of peripheral skinfolds was found in the ICSI group compared with the SC group (difference 3.5 mm, 95% confidence interval 0.3-6.6). In girls, peripheral adiposity assessed by skinfolds and mid-upper arm circumference, and central adiposity assessed by skinfolds and waist circumference as well as total adiposity assessed by BMI, the sum of four skinfold thicknesses and skinfold-derived body fat percentage were significantly higher in the ICSI group compared with the SC group, taking into account confounding variables (all P< 0.05). Neither parental nor early life factors could explain the differences. CONCLUSIONS We found that pubertal ICSI girls were more prone to central, peripheral and total adiposity compared with their SC counterparts. ICSI adolescents with advanced pubertal stages showed more peripheral adiposity. Continued monitoring of body fat patterns in adolescents born after fertility treatment is mandatory in order to assess their risk for developing obesity and its related adverse health effects in adulthood.