Vekststudien i Bergen

Publications

Dr. Pétur Júlíusson — Tue, 11 Oct 2011 12:28:01 +0000

Brannsether B, Roelants M, Bjerknes R, Júlíusson PB. Waist circumference and waist-for-height ratio in Norwegian children 4-18 years – reference values and cut-off levels. Acta Paediatrica 2011. Epub May 31. http://www.ncbi.nlm.nih.gov/pubmed/21627692

Júlíusson PB. Overweight and obesity in Norwegian children: Trends, current prevalence, effect of socio-demographic factors and parental perception. PhD thesis. University of Bergen, Norway, 2010. http://hdl.handle.net/1956/4504

Júlíusson PB, Roelants M, Markestad T, Bjerknes R. Parental perception of overweight and underweight in children and adolescents. Acta Paediatr 2011;100:260-5. http://www.ncbi.nlm.nih.gov/pubmed/20973817

Júlíusson PB, Eide GE, Roelants M, Waaler PE, Hauspie R, Bjerknes R. Overweight and obesity in Norwegian children: prevalence and socio-demographic risk factors. Acta Paediatr 2010;99:900-5. http://www.ncbi.nlm.nih.gov/pubmed/20175763

Westerberg AC, Henriksen C, Ellingvåg A, Veierød MB, Júlíusson PB, Nakstad B, Aurvåg AK, Rønnestad A, Grønn M, Iversen PO, Drevon CA. First year growth among very low birth weight infants. Acta Paediatrica 2010;99:556-62. http://www.ncbi.nlm.nih.gov/pubmed/20096031

Júlíusson PB, Roelants M, Hoppenbrouwers K, Hauspie R, Bjerknes R. Growth of Belgian and Norwegian children compared to the WHO growth standards: Prevalence below –2 and above +2 standard deviations and the effect of breastfeeding. Arch Dis Child 2011;96:916-21. http://adc.bmj.com/cgi/rapidpdf/adc.2009.166157v1

Júlíusson PB, Roelants M, Bjerknes R. Vekstkurver: Hva er forskjellene mellom en referanse og en standard? Pediatrisk Endokrinologi 2009;23:53-6. http://pediatrisk-endokrinologi.no/2009-1/

Júlíusson PB, Roelants M, Eide GE, Moster D, Juul A, Hauspie R, Waaler PE, Bjerknes R. Vekstkurver for norske barn. Tidsskr Nor Legeforen 2009;129:281-6. http://www.tidsskriftet.no/index.php?seks_id=1800163

Júlíusson PB, Bjerknes R. Sekulær økning i vekt hos barn og unge. Pediatrisk Endokrinologi 2008;22:16-24. http://pediatrisk-endokrinologi.no/2008-1/

Júlíusson PB, Roelants M, Eide GE, Hauspie R, Waaler PE, Bjerknes R. Overweight and obesity in Norwegian children: Secular trends in weight-for-height and skinfolds. Acta Paediatrica 2007;96:1333–7. http://www.ncbi.nlm.nih.gov/pubmed/17718787

Júlíusson PB, Roelants M. Internasjonal definisjon av overvekt og fedme hos barn: Noe for bruk i Norge? Pediatrisk Endokrinologi 2007;21:29-32. http://pediatrisk-endokrinologi.no/2007-1/

Júlíusson PB, Vinsjansen S, Nilsen B, Sælensminde H, Vågset R, Eide GE, Waaler PE, Bjerknes R. Måling av vekst og vekt: En oversikt over anbefalte teknikker. Pediatrisk Endokrinologi 2005;19:23-9. http://pediatrisk-endokrinologi.no/2005-1/

Kongresspresentasjoner

Júlíusson PB, Roelants M, Markestad T, Bjerknes R. Parental perception of overweight and underweight in children and adolescents. 39th Congress of the European Society of Paediatric Endocrinology (ESPE), Prague, september 2010.

Júlíusson P, Roelants M, Hoppenbrouwers K, Hauspie R, Bjerknes R. Growth of Belgian and Norwegian children compared to the WHO growth standards: prevalence outside normal limits and the effect of breastfeeding. LWPES/ESPE 8th joint meeting, New York, USA, 9.-12. september 2009. Hormone Research 2009;72(suppl 3):199.

Juliusson PB, Roelants M, Eide GE, Waaler PE, Bjerknes R. Comparison of new Norwegian growth curves with excisting national charts and the WHO growth standards. 37th Congress of the European Society of Paediatric Endocrinology (ESPE), Istanbul, september 2008. Hormone Research 2008;70(suppl 1):88.

Júlíusson PB, Roelants M, Eide GE, Moster D, Juul A, Waaler PE, Hauspie R, Bjerknes R. Nye vekstkurver for norske barn i alderen 0-19 år. Norsk Barnelegeforening, vårmøte, Fredrikstad, 30. mai 2008.

Júlíusson PB, Roelants M, Eide GE, Hauspie R, Waaler PE, Bjerknes R. Overweight and obesity in Norwegian children: Secular trends in weight-for-height and skinfolds. 36th Congress of the European Society of Paediatric Endocrinology (ESPE), Helsinki, juli 2007.Hormone Research 2007;68(suppl):136.

Júlíusson PB, Eide GE, Roelants M, Hauspie R, Waaler PE, Bjerknes R. Secular changes in height and weight among Norwegian children: the Bergen Growth Study. 34th Congress of the European Society of Paediatric Endocrinology (ESPE), Lyon, september 2005. Hormone Research 2005;64(suppl 1):191.

Júlíusson P, Eide GE, Roelants M, Hauspie R, Waaler PE, Bjerknes R. Sækulære trender i høyde og vekst hos norske barn. Norsk Barnelegeforrering, høstmøte, Ullevål, 13-15. oktober 2005.

About the Bergen Growth Study

Dr. Pétur Júlíusson — Tue, 11 Oct 2011 11:20:33 +0000

PRINCIPAL INVESTIGATORS

Petur Juliusson
Robert Bjerknes
Barneklinikken, Haukeland Universitetssykehus, Bergen; Institutt for klinisk medisin, seksjon for pediatri, Universitetet I Bergen, Bergen

COLLABORATORS

Brussel

Mathieu Roelants
Roland Hauspie
Vrije Universiteit Brussel, Laboratory for Anthropogenetics, Brussel, Belgia

Norway

Geir Egil Eide
Centre for Clinical Research, Haukeland University Hospital, Bergen

Bente Brannsether Ellingsen
Stavanger University Hospital, Stavanger

Hege Kristiansen
Førde Hospital

Dag Moster
Department of Public Health and Primary Health Care, University of Bergen

Copenhagen

Anders Juul
Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Denmark

BACKGROUND

Children’s growth and development is dynamic and is at some level reflecting the environment. Secular trends in children’s length growth and final height has been described over the last hundred years and reflects improved job satisfaction, improved nutrition and fewer infections (1). Updated knowledge about growth and growth parameters is important for all health-related work with children and adolescents, both in order to follow up the child, and to follow trends in the child population. On an individual basis this applies to issues such as low or high altitude, abnormal body proportions, pubs minority, as well as over-or under-weight. The population base is including the question of whether there are adverse changes in weight in the child population that should trigger social measures.

The first Norwegian growth curves were constructed by Sundal on the basis of measurements of head circumference performed in Oslo in 1949 (2), and measurement of height and weight collected in Bergen in the period 1950-6 (3). In 1971-4 Waaler followed this up with a study of 3-17 year old children in Bergen, which formed the basis for the current percentile curve for length, weight and head circumference in children older than 4 years (4, 5). The current references for children aged 0-4 years from the SYSBARN- survey conducted in Oslo and Hedmark in 1982-4, and data from the Medical Birth Registry (6). The current Norwegian references are based on measurements performed 23-36 years ago.

There has been a worrying increase of overweight and obesity in recent decades in developed countries, a trend that is also now seen in developing countries. The prevalence of obesity has 2-3 doubled in the last years in the U.S. and Europe and it is now between 12% and 20% in children aged 7-11 years in Northern and Western European countries (7, 8, 9) Obesity is already a serious problem in childhood and child obesity is related to increased morbidity and mortality in adulthood (10, 11, 12).

The increase in the number of children with overweight and obesity demonstrates the importance of good clinical tools to assess overweight and obesity. Today’s references has only the weight-against-height curves, but now body mass index (body mass index, kg/m2 (BMI)) has been internationally recommended for use to assess the degree of overweight and obesity. BMI curves for children and the youth population have been missing in Norway, but are now made for the first time under the direction of the Bergen growth study.

AIMS

1. Provide information on length / height and body proportions. The latter involves measurements of sitting height, arm-spen, head circumference, forearm length and leg length.

2. Provide information on overweight and obesity in Norwegian children and adolescents, to compare measurements of body mass index, skin folds and stomach size.

3. Provide information on growth rate.

4. Identify factors that can affect growth and weight development in Norwegian children.

5. Designing clinically relevant percentile / SD curves for a range of growth parameters

MATERIALS AND METHODS

Design

A. Cross-sectional survey to assess growth and weight parameters. This was conducted from November 2003 to December 2006. The following measurements were made:
# Length / height and weight among children 0-19 years old
# head circumference I0-15 years old children
# Sitting height and leg size in 4-19 year old children
# Arms Penn, skin folds, underarm and leg-length in children 4-15 years old.

B. Longitudinal study to determine growth rate. About half the children aged 6-18 were measured one year later, then only measurement of height and weight. Data collection was conducted in the period 2004-2006.

C. C. Identification of factors that can affect growth and weight development. Parts of this study involved performing a survey and forwarding the data to existing databases. The survey was conducted in 2006 and 2007. The response rate was 67%. The survey contains 38 questions to all parents who had children aged less than 15 years at the time of measurement.

D. Design of clinically relevant growth curves.

Child Population

Cross-sectional survey was conducted from November 2003 to December 2006 when a total of 8312 children aged 0-19 years were included and measured. The children were recruited from the Bergen based on stratified random selection of health clinics (n = 8), day care centers (n = 34) and schools (n = 24, including 19 primary and or secondary schools and 5 high schools). All children were invited to participate, but only children where there was a written consent from parents and / or children to participate, were measured. At health centers, around 98% of available children were measured. Participation rate was 57% in kindergarten, 69% in primary schools (1st-7. age groups), 53% in secondary schools (8th-10. step) and in upper secondary schools (1st-3rd. increments). Part- time in kindergarten, activities in the kindergarten or school measure days and travel and sickness absence were all factors that influenced the attendance in addition to the fact that some did not want to participate.

Measurements (13)

The children were measured by public health nurses employed in the study of health centers, while children in kindergartens and schools were measured by study nurses who work in teams, two and two together. Measurements, performed between 08.30 and 13.00, were recorded directly onto laptop computers.

Surface length was measured up to two years of age with Harpenden Infant Measuring Table. The children were measured naked, but with panties and t-shirts on. The head was held by parents up to the head plate, so that the lower edge of orbit stayed in line with the ear opening. Both legs were extended by the school nurse, and the movable plate led to the soles.

At two years of age height was measured standing using the Holtain Portable Stadiometer. The children were measured naked, but with panties and t-shirts on. The measurements were performed without shoes and socks to make sure foot suspension was appropriate and heals were not lifted from the floor. The children were measured with the feet together and with heal buttocks and shoulders into the meter. If the hair was thick, a light pressure was applied to the head plate. The children were asked to “stand straight” and the measurements were taken during normal respiration. Head position was such that the lower edge of orbit stayed in horizontal line with the ear opening.

Weight was measured at the clinic without a nappy using a digital infant weight (Seca). In kindergartens and schools weight was measured wearing panties, occasionally bra, using a digital weight (Seca).

When measuring the head circumference, the greatest head circumference was measured with a metal measuring tape, (Lufkin).

Quality control

At the start of each measuring day, measuring equipment, height and length measure were checked. Person weights at health centers were checked twice a year and at school or in Kindergarten every time they were moved (to a new school / kindergarten). Twice a year, all the performers would meet at a common training session. 10 children were measured twice by all the performers. Measurement accuracy was assessed as well as the variation between the meters.

Statistical analysis

Calculations of sample size were performed on the basis of the statistical strength.
Percentile curves were prepared using the LMS method (14). The data is also analyzed with the software programs SPSS, STAT, and R.

RELEVANT MAIN RESULTS

1. Increase in weight against height in children and adolescents (15).

Amongst children aged 4-16 years, the prevalence of overweight and obesity 12.5% and 2.1% in boys and 14.8% and 2.9% in girls (cf. IOTF-cut-offs). Compared with figures from the 1970s years is 8% of boys and 7.2% of girls of 97.5 – percentile of weight-for-height from 19771-4 (forstår ikke denne setningen..). The difference is greatest in the top percent missiles, while the lowest is unchanged. Growth increase limits therefore largely a subset of the Norwegian child population. The study also shows the increase in skin folds. Only ethnic Norwegian children were included in this analysis to make it comparable with the figures from the 1970s

2. New growth curves for Norwegian children aged 0-19 years (16)

On the basis of data from the Bergen growth study new percentile curves have been developed for ages 0-12 months (respectively, head circumference, length and weight against age) 1-5 years (respectively, head circumference, length / height and weight against age), 4-19 years (respectively, height and weight against age) and 2-19 (body mass index (BMI) for age). On the curves, a gray field that defines the area between the median 2.0 to 2.5 standard deviations (s) and the median area between -2.0 to -2.5 s are added. The BMI curve has specified limits for overweight, obesity and underweight. The new curves reflect the growth of Norwegian children of today and can replace the existing growth curves when growth and weight development is to be followed in primary- or specialist health services.

3. The new curves compared with the existing Norwegian reference (16).

In today’s children aged 0-4 years, the length / height and weight are only marginally changed from the existing growth curves. For older children, however there is an increase in the 50 percentile for height up to 3.4 cm in boys and 2.5 cm in girls. For children over 4 years, weight for height is also increased, particularly in the top percent missiles. Secular growth trends reflect the need for new growth curves.

4. The new growth curves compared with international growth curves of WHO for ages 0-5 years (16)

The curves of the current Norwegian children are above WHO curves for birth weight, length / height, weight and head circumference for age group 6 months to 5 years of age, which may reflect differences in the environment or growth potential between the populations.

Referanser

1. Werner B. Sekulära förändringer i kroppslängd. Pediatrisk Endokrinologi 2008;22:6-15.

2. Sundal A. Hodets største omkrets hos barn fra fødselen til syv års alder. Tidsskr Nor Lægefor 1949;69:688-89.

3. Sundal A. The norms for height (length) and weight in healthy Norwegian children from birth to 15 years of age. Bergen: Universitetet i Bergen; 1957.

4. Waaler PE. Anthropometric studies in Norwegian children. Acta Paediatr Scand Suppl 1983;308:1-41.

5. Knudtzon J, Waaler PE, Skjaerven R, Solberg LK, Steen J. [New Norwegian percentage charts for height, weight and head circumference for age groups 0-17 years]. Tidsskr Nor Lægeforen 1988;108:2125-35.

6. Knudtzon J, Waaler PE, Solberg LK, Grieg E, Skjaerven R, Steen J, et al. [Height, weight and head circumference of 0-4 year-old children. Data based on the SYSBARN registration and medical register of births]. Tidsskr Nor lægeforen 1988;108:2136-42.

7. Ebbeling CB, Pawlak DB, Ludwig DS. Childhood obesity: public-health crisis, common sense cure. Lancet 2002;360:473-82.

8. Chinn S, Rona RJ. Prevalence and trends in overweight and obesity in three cross sectional studies of British Children, 1974-94. BMJ 2001;322:24-6.

9. Fredriks AM, van Buuren S, Wit JM, Verloove-Vanhorick SP. Body index measurements in 1996-7 compared with 1980. Arch Dis Child 2000;82:107-12.

10. Whitaker RC, Pepe MS, Wright JA, Seidel KD, Dietz WH. Early adiposity rebound and the risk of adult obesity. Pediatrics 1998;101:E5.

11. Engeland A, Bjorge T, Sogaard AJ, Tverdal A. Body mass index in adolescence in relation to total mortality: 32-year follow-up of 227,000 Norwegian boys and girls. Am J Epidemiol 2003;157:517-23.

12. Sayer AA, Syddall HE, Dennison EM, Gilbody HJ, Duggleby SL, Cooper C, et al. Birth weight, weight at 1 y of age, and body composition in older men: findings from the Hertfordshire Cohort Study. American J Clin Nutr 2004;80:199-203.

13. Juliusson P, Vinsjansen S, Nilsen B, Sælensminde H, Vågset R, Eide G, et al. Måling av vekst og vekt: En oversikt over anbefalte teknikker. Pediatrisk Endokrinologi 2005;19:23-9.

14. Cole TJ. The LMS method for constructing normalized growth standards. Eur J Clin Nutr. 1990;44:45-60.

15. Juliusson P, Roelants M, Eide G, Hauspie R, Waaler P, Bjerknes R. Overweight and obesity in Norwegian children: Secular trends in weight-for-height and skinfolds. Acta Paediatr 2007;96:1333-7.

16. Júlíusson PB, Roelants M, Eide GE, Moster D, Juul A, Hauspie R, Waaler PE, Bjerknes R. Vekstkurver for norske barn. Tidsskr Nor Legefor 2009;129:281-6.

17. Júlíusson PB, Roelants M, Hoppenbrouwers, Hauspie R, Bjerknes R. Growth of Belgian and Norwegian children compared to the WHO growth standards: prevalence below -2 and >2 SD and the effect of breastfeeding. Arch Dis Child 2010 Jun 3. [Epub ahead of print].

New growth curves for Norwegian children aged 0-19 years

Dr. Pétur Júlíusson — Tue, 11 Oct 2011 10:56:05 +0000

INTRODUCTION

Children’s growth and development are dynamic and reflects in part the environment. Secular trends in children’s height and final height has been described over the last hundred years, and reflects changes in the environment with improved nutrition and fewer infections. Over the last 20-30 years there has been a rapid and large change in weight in older children and adults.

The first Norwegian growth curves were drawn in Bergen in the 1950s and the data for the second generation of curves (1971-4) were also collected in the same city.

In the period of November 2003 to December 2006, children at the age of 0-19 years were measured at well-baby clinics, kindergartens and schools in the city of Bergen. Above 8000 children were measured and included in the study with the intent to obtain updated information on growth and weight parameters in children in Norway. Measurements of length/height, sitting height, armspenn, under arm- and leg-length, head circumference, weight, waist circumference and skin folds (triceps and subscapularis), were performed. In 2006-2007, questionnaires to more than 7000 parents were sent out. The purpose of the questionnaire was to identify factors that may affect growth and weight trends. Approximately 67% answered the questionnaire.

Results from the study has made it possible to compare measurements of weight against height and skin folds (triceps and subscapularis) against age, of 4115 healthy children measured during 2003-2006, with similar surveys conducted by Per Erik Waaler in Bergen in 1971-1974. Only ethnic Norwegian children were included in this analysis to make it comparable to the Waaler study. In the material from the Bergen Growth Study, at the age of 4-15 years, 18% of the boys and 20.1% of the girls exceeded the 90th centile, for weight to height in the Waaler study. When it came to skin folds, changes were slightly greater. For the triceps, 30% of boys and 28% of girls exceeded 90th centile of the Waaler study. The same number off subscapularis were respectively 26.5% and 25.9%. The prevalence of overweight and obesity was 12.5% and 2.1% in boys and 14.8% and 2.9% in girls (IOTF cut-off’s).

Growth curves for Norwegian children aged 0-19 years are developed on the basis of data from the Bergen Growth Study. These are published in the Journal of the Norwegian Medical Association and compared with current Norwegian curves and WHO growth standards (Juliusson PB, Roelants M, Eide GE, Moster D, Juul A, Hauspie R, Waaler PE, Bjerknes R. The growth curves for Norwegian children. Tidssr Nor Doctors Unite 2009; 129:281-6). The length and weight in children aged 0-4 years has only slightly changed from the growth curves that are in use. Norwegian school children, however, are higher today than in the 1970s, with an increase in the median (50th percentile) for height up to 3,4 cm for the boys and 2,5 cm for the girls, compared to the Waaler study. The new curves are above the WHO growth standards for birth weight and length, and weight and head circumference at age 6 months-5 years. In the autumn 2010 new charts for weight-for-length/height for 0-5 year-old children were released.

BACKGROUND

Compared with the previous Norwegian growth curves, the Bergen growth study shows that the Norwegian children have become higher and the heaviest have become heavier than 25-35 years ago. This makes it necessary to develop new growth curves.

The curves that are presented here(1), are basis-curves that are needed in all health work with children. Later, special-curves will be made for the assessment of growth proportions (for example, sitting height, arm spen, forearm length, leg length and stomach scope.)

THE CHILDREN POPULATION

In 2003-2006, 8299 children aged 0-19 years were measured at randomly selected health centers, kindergartens and schools in the Bergen municipality. The data for growth curves of 936 children in whom one or both parents were from countries outside the Nordic region, and 85 children with chronic illness or prematurity were excluded. Measurements from a total of 7278 children were therefore used in the work of these curves, including data from 3756 boys and 3535 girls. 2736 children were younger than 5 years of age. Data from the birth length, birth weight and head circumference at birth was obtained from the Medical Birth Registry. Data from pubertal development is taken from the latest available study in Scandinavia and is based on surveys of 1925 Danish boys and girls aged 6 to 19.9 years from the Copenhagen area, collected in 1991-1993 (2).

MEASUREMENT TECHNIQUES

Standardized measurement techniques were used, that you can read more about here.

STATISTICAL ANALYSIS AND PREPARATION OF THE CURVES

The percentile curves were developed by using the growth model LMS developed by Cole and Green (3).

GENERAL DESCRIPTION

The new percentile curves presents the length / height, head circumference and body mass index (BMI) and is divided into three age intervals, 0-1 years, 1-5 years and 4-19 years. In addition to the percentile lines, gray fields are added representing respectively the area between median +2.0 to
+2.5 standard deviation (s) and median -2.0 to -2.5 (s). The axes are linear. On the curves, there is a table to insert the current measurements and space to write the name and date of birth. Furthermore, the curves have some relevant definitions and explanations inserted. Separating the reference material in the three age intervals provides good distance between the individual percentile lines and thus functional workplace on the charts.

The curves of respectively 0-1 and 1-5 year old children have the same template. At the top of the sheet, the head circumference against age is inserted, in the middle, length / height against age and lower weight against age. Curve sheet for children and adolescents aged 4-19 years, shows the top elevation mt age and weight against age at the bottom. BMI curves are designed for ages 2-19 years. Here, a gray area at the top is added representing the International Obesity Task Force (IOTF) their values for overweight and obesity (4). These are based on the BMI of at least 25.0 kg/m2 (overweight) (iso-BMI 25) and 30.0 kg/m2 (obesity) (iso-BMI 30) at age 18 years and is extrapolated down the ages. This was done that the same standardized deviation scores were followed up from the representative point by age 18 years and under (4). The BMI curves are also entered in the World Health Organization (WHO) limits for grade 1 and grade 2 under-weight. These are based on BMI 18.5 kg/m2 (grade 1 under -weight) and 17, 0 kg/m2 (grade 2 under-weight) at age 18 years, also extrapolated into the age (5).

On the growth curves for ages 4-19 years, references to pubertal development is added. On the curves for boys, percentiles for “T4 ml” (i.e. testis size 4 ml), which is consistent with puberty start and P2-P4 (Tanner-stages pubs minority hairs (6)) is included. On the curves for the girls, percentiles for B2-B4 (-Tanner stages for breast development (7)), P2-P4, and percentiles of menarche is added.

The growth curves are based on a cross-sectional- study and therefore gives a description of how the length / height, weight or head circumference of the individual child is compared with other children, each time. The growth curves say less about the expected growth development of the individual child.

Due to a long tradition in Norway using percentile-curves, also the new curves have percentile lines. The percentile-curves are believed to be easier to explain and are easier understood by parents and children. Standard deviation is still better suited for research purposes with the calculation of standardized deviation scores. National and international definitions and event terms are used in increasingly critical values where the standard deviations are included, for example, the definition of children born small for gestational age (8), and the risk of children with short stature applies(9). The new carts combine both approaches, using percentile lines with the gray areas that represent the median of 2 to 2.5, and -2 to -2.5 s.

THE HEAD CIRCUMFERENCE-FOR-AGE CURVE

The curves show the development of head circumference from birth up to 5 years of age. There are some differences, like when comparing with the earlier reference the new curve is slightly below. The difference has no clinical significance, and is believed to be caused by differences in measurement techniques and standardization. SYSBARN- registration in the 1980s routinely collected measurements from the health centers, while the measurements were performed in the Bergen Growth study by a limited number of nurses and nurses with special training in standardized measurement techniques.

Head circumference should be measured by all the Health centers the first 12 months of life (10). At the intersection of 1-2 percentile channels without suspect findings, repeated measurement should be made after 4 weeks. By clinical findings or intersection of 3 percentile channels the child should be assessed, but healthy children with head circumference below 3 percentile should only be referred if the head circumference blunt from the 3 percentile (10).

THE LENGTH/HEIGHT-FOR-AGE CURVE

The new curves have the same reference for children 4 years and younger as the once that have been used until now. For older children, there is however an increase in the 50 percentile for height up to 3,4 cm in boys and 2.5 cm in girls, in “line” with Norwegian children in these age group has become higher.

At the transition from the measurement of length while lying (from birth up to 2 years of age) to standing height (after 2 years) the difference is slight, usually less than 1 cm. Compared to how it has been done in some other countries (11.12), and in the former Norwegian growth curves, the new curves are smooth with no “notch” at 2 years of age.

Experience has shown that crossing of lines are normal the first 2 to 3 years of life, a phenomenon that can also normally be seen around puberty. It is customary to define short stature as height <2.5 percentile for the age. Most children who are below the 2.5 percentile are healthy and do not need investigation. Height should be assessed against the genetic potential and the current level is well below mid-parental height adjusted for age, the report indicated. Flattening of length or height should be investigated if the child has crossed two percentile lines between measurements and are under 5 years of age (10). Children who are below the 2.5 percentile, above the 97.5 percentile, or has crossed a percentile-line and are more than18 months, should be followed up with annual length / height measurements until clarification (10).

THE WEIGHT-FOR-AGE CURVE

In children younger than 4 years the new curves are consistent with earlier references. In children aged 4-19 years, however the highest percentile has increased in line with the increase in prevalence of overweight and obesity.

Assessment of overweight and obesity should include calculating and plotting of the body mass index (BMI). In children under the age of 5 years, weight against age should always be considered against weighed against the length / height to age. Children under 2.5 percentile or above the 97.5 percentile should be considered in terms of morbid weight deviations.

THE BMI-FOR-AGE CURVE

BMI curves for children is now made for the first time in Norway and onto these are included internationally recognized limits, respectively, overweight and obesity as proposed by the IOTF (4). This is rugged lines that can not be changed with secular trends. Therefore there is a clear indication in the curves when a child is at risk for developing overweight or obesity. The stated limit value for overweight, obesity and underweight is still primarily a screening tool and not a diagnostic tool for the individual child (13). It is important to keep in mind that BMI has its limitations, and that it should be used as an addition to clinical examination (14,15). BMI tells nothing about factors like fat distribution in the body (central versus peripheral), which in turn is linked to health risks (16). Furthermore, BMI differs poorly between muscle and fat, and BMI may therefore be unchanged when muscle mass increases and fat mass decreases, as during exercise (17). On the BMI curves, there are also added limit values for grade 1 and grad2 underweight (5).

Upon suspicion of weight discrepancy, over or under weight, BMI should be calculated and plotted. If iso-BMI exceeds 25, it should be perceived as a danger signal in terms of obesity development, especially if there is a preponderance of the family. If iso-BMI exceeds 30, there is considerable overweight and measures should be implemented. Warning signs of the under weight is if the child’s BMI is below level 1 (ref guidelines).

THE REFERENCE FOR PUBERTAL DEVELOPMENT

An overview of the pubertal development of Danish children were included when the new curves were recorded in the years 1991 to 1993 (2). It shows no change in pubs minority point compared to a Danish study from 1964. Menarche age registered in the Bergen growth study (data not shown here), shows good correlation with the Danish puberty reference. Median (50 – percentile) in both cases is slightly above 13 years (18), suggesting that the secular trend in growth and weight are not accompanied by a corresponding secular trend in puberty. Previous growth curves adopted Tanner percentiles in pubertal development, based on surveys of English children in the 1950s (19). The Danish reference shows no systematic differences from the English, and the largest deviations for the different percentiles are up to six months.

Percentile for testicular volume is presented for the first time within the new curves. The background is that the first clinical signs of puberty in normal puberty in boys are testicular volume of 4 ml.

1. Júlíusson PB, Roelants M, Eide GE, Moster D, Juul A, Hauspie R, Waaler PE, Bjerknes R. Vekstkurver for norske barn. Tidsskr Nor Legefor 2009;129:281-6.

2. Juul A, Teilmann G, Scheike T, Hertel NT, Holm K, Laursen EM, et al. Pubertal development in Danish children: comparison of recent European and US data. Int J Androl. 2006;29:247-55.

3. Cole TJ, Green PJ. Smoothing reference centile curves: the LMS method and penalized likelihood. Stat Med. 1992l;11:1305-19.

4. Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ 2000;320:1240-3.

5. Cole TJ, Flegal KM, Nicholls D, Jackson AA. Body mass index cut offs to define thinness in children and adolescents: international survey. BMJ 2007;335:194.

6. Marshall WA, Tanner JM. Variations in the pattern of pubertal changes in boys. Arch Dis Child 1970;45:13-23.

7. Marshall WA, Tanner JM. Variations in pattern of pubertal changes in girls. Arch Dis Child 1969;44:291-303.

8. Saenger P, Czernichow P, Hughes I, Reiter EO. Small for gestational age: short stature and beyond. Endocr Rev 2007;28:219-51.

9. Consensus guidelines for the diagnosis and treatment of growth hormone (GH) deficiency in childhood and adolescence: summary statement of the GH Research Society. GH Research Society. JCEM 2000;85:3990-3.

10. Retningslinjer for veiing og måling av barn og ungdom: Sosial- og helsedirektoratet; 1997.

11.http://www.cdc.gov/nchs/about/major/nhanes/growthcharts/clinical_charts.htm#Clin%201

12. Fredriks M. Growth diagrams 1997. Fourth Dutch nation-wide survey. Leiden: Leiden University medical center; 2004.

13. Flegal KM, Tabak CJ, Ogden CL. Overweight in children: definitions and interpretation. Health Educ Res 2006;21:755-60.

14. Dietz WH, Robinson TN. Use of the body mass index (BMI) as a measure of overweight in children and adolescents. J Pediatr 1998;132:191-3.

15. Chinn S. Definitions of childhood obesity: current practice. Eur J Clin Nutr. 2006;60:1189-94.

16. Freedman DS, Serdula MK, Srinivasan SR, Berenson GS. Relation of circumferences and skinfold thicknesses to lipid and insulin concentrations in children and adolescents: the Bogalusa Heart Study. Am J Clin Nutr 1999;69:308-17.

17. Hall DM, Cole TJ. What use is the BMI? Arch Dis Child 2006;91:283-6.

18. Liestol K, Rosenberg M. Height, weight and menarcheal age of schoolgirls in Oslo–an update. Ann Hum Biol 1995;22:199-205.

19. Tanner JM, Whitehouse RH. Clinical longitudinal standards for height, weight, height velocity, weight velocity, and stages of puberty. Arch Dis Child 1976;51:170-9.

Media coverage of the growth study

Vekststudien i Bergen — Sun, 09 Oct 2011 19:45:55 +0000

April 4th 2010
Søsken gir mindre overvekt in “På høyden”

February 12th 2009
Norske barn veks in “Bergens Tidende”

September 29th 2008
Tykke barn er blitt tykkere in “Verdens Gang”

April 19th 2005
Tunge barn er blitt tyngre in “Aftenposten”

Publikasjoner

Vekststudien i Bergen — Sun, 29 May 2011 20:34:25 +0000

Júlíusson PB, Roelants M, Bjerknes R. Vekstkurver: Hva er forskjellene mellom en referanse og en standard? Pediatrisk Endokrinologi 2009;23:53-6. http://pediatrisk-endokrinologi.no/2009-1/

Júlíusson PB, Bjerknes R. Sekulær økning i vekt hos barn og unge. Pediatrisk Endokrinologi 2008;22:16-24. http://pediatrisk-endokrinologi.no/2008-1/

Júlíusson PB, Roelants M. Internasjonal definisjon av overvekt og fedme hos barn: Noe for bruk i Norge? Pediatrisk Endokrinologi 2007;21:29-32. http://pediatrisk-endokrinologi.no/2007-1/

Abstracts

Júlíusson P, Eide GE, Roelants M, Hauspie R, Waaler PE, Bjerknes R. Sækulære trender i høyde og vekst hos norske barn. Norsk Barnelegeforrering, høstmøte, Ullevål, 13-15. oktober 2005.

Nye vekstkurver for norske barn i alderen 0-19 år

Vekststudien i Bergen — Sun, 29 May 2011 13:32:33 +0000

Barns vekst og utvikling er dynamisk og reflekter til dels omgivelsene. Sekulære trender i barnas høyde, samt slutthøyde, har vært beskrevet de siste hundre år og gjenspeiler at miljøet har endret seg med bedre trivsel, forbedret ernæring og færre infeksjoner. De siste 20-30 årene har det også foregått nokså raske og store endringer i vekt hos eldre barn og voksne.

Første norske vekstkurvene ble utarbeidet i Bergen på 1950-tallet og datamaterialet til den andre generasjonen av norske vekstkurver ble også innsamlet i Bergen (1971-4).

I perioden november 2003 – desember 2006 ble barn i alderen 0-19 år målt på helsestasjoner, barnehager og skoler i Bergen. Totalt ble godt over 8000 målt og inkludert i studien som har den hensikt å skaffe oppdatert informasjon om vekst- og vektparametere hos barn i Norge. Målinger av lengde/høyde, sittehøyde, armspenn, underarms- og legglengde, hodeomkrets, vekt, mageomfang og hudfolder, ble utført. I 2006-7 ble over spørreskjema sendt ut til over 7000 foresatte. Hensikten med spørreskjemaet er å kartlegge faktorer som kan påvirke vekst- og vektutviklingen. Ca. 67% har besvart spørreskjemaet.

Resultater fra studien har gjort det mulig å sammenligne målinger av vekt mot høyde og hudfolder mot alder (triceps og subscapularis) til 4115 friske barn målt i 2003-6 med like målinger utført av Per Erik Waaler 1971-4 i Bergen. Kun etnisk norske barn ble inkludert i denne analysen for å gjøre den sammenlignbar med Waalers studie. I materialet fra Vekststudien i Bergen lå 18 % av guttene og 20,1 % av jentene i alderen 4-15 år over 90-prosentilen for vekt mot høyde i Waalers studie. For hudfoldene var endringen noe større, for triceps lå 30% av guttene og 28% av jentene over 90-prosentilen til Waalers studie, for subscapularis var samme tall henholdsvis 26,5% og 25,9%. Forekomsten av overvekt og fedme var 12,5% og 2,1% hos gutter, og 14,8% og 2,9% hos jenter (IOTF internasjonale grenseverdier).

Vekstkurver for norske barn i alderen 0-19 år er utarbeidet på grunnlag av dataene fra Vekststudien i Bergen. Disse er publisert i Tidsskrift for Den norske legeforening og sammenlignet med dagens norske kurver og WHOs vekststandard (Júlíusson PB, Roelants M, Eide GE, Moster D, Juul A, Hauspie R, Waaler PE, Bjerknes R. Vekstkurver for norske barn. Tidsskr Nor Legeforen 2009;129:281-6). Barn i alderen 0-4 år har i dag lengde og vekt som kun i liten grad er endret fra de vekstkurvene som er i bruk. Norske skolebarn er derimot høyere i dag enn på 1970-tallet, med økning i medianen (50-prosentilen) for høyde med opp til 3,4 cm hos gutter og 2,5 cm hos jenter sammenlignet med Waalers studie. De nye kurvene ligger over WHOs vekststandard for fødselsvekt, og lengde, vekt og hodeomkrets i alderen 6 mnd – 5 år. Høsten 2010 ble kurver for vekt-mot-lengde/høyde utarbeidet for barn i alderen 0-5 år.

Prosjektoversikt

Vekststudien i Bergen — Sun, 29 May 2011 13:31:39 +0000

Leder/daglig ansvar

Pétur B. Júlíusson
Robert Bjerknes
Barneklinikken, Haukeland Universitetssykehus, Bergen; Institutt for klinisk medisin, Seksjon for pediatri, Universitetet i Bergen, Bergen

Samarbeidspartnere

Brussel

Mathieu Roelants
Roland Hauspie
Vrije Universiteit Brussel, Laboratory for Anthropogenetics, Brussel, Belgia

Bergen

Geir Egil Eide
Institutt for samfunnsmedisinske fag, Seksjon for epidemiologi og medisinsk statistikk, Universitetet i Bergen

Dag Moster
Locus for registerepidemiologi, Institutt for samfunnsmedisinske fag, Universitetet i Bergen

Stavanger

Bente Brannsether Ellingsen
Barneavdelingen, Stavanger Universitetssykehus

Førde

Hege Kristiansen
Barneavdelingen, Førde Sentralsykehus

København

Anders Juul
Afdeling for Vækst og Reproduktion GR, Rigshospitalet, Københavns Universitet, København Ø, Danmark

Bakgrunn

Barns vekst og utvikling er dynamisk og reflekterer til dels omgivelsene. Sekulære trender i barns lengdevekst og slutthøyde har vært beskrevet de siste hundre år og gjenspeiler bedre trivsel, forbedret ernæring og færre infeksjoner (1). Oppdatert kunnskap om vekst- og vektparametere er viktig for alt helsearbeid med barn og unge, både for å kunne følge opp det enkelte barnet og for å følge trender i barnebefolkningen. På individbasis gjelder dette problemstillinger som lav eller stor høyde, unormale kroppsproporsjoner, pubertetsutvikling, samt over- eller undervekt. På populasjonsbasis gjelder det bl.a. spørsmål om det foreligger uheldige endringer i vekt hos barnebefolkningen som bør utløse samfunnsmessige tiltak.

De første norske samlede vekstkurver ble konstruert av Sundal på basis av målinger av hodeomkrets utført i Oslo i 1949 (2), og målinger av høyde og vekt innsamlet i Bergen i perioden 1950-6 (3). I 1971-4 fulgte Waaler dette opp med en studie av 3-17 år gamle barn i Bergen som dannet grunnlaget for dagens prosentilkurver for lengde, vekt og hodeomkrets hos barn eldre enn fire år (4, 5). Dagens referanser for barn i alderen 0-4 år kommer fra SYSBARN-undersøkelsen utført i Oslo og Hedmark i 1982-4, samt data fra Medisinsk fødselsregister (6). De gjeldende norske referansene er derfor basert på målinger utført for 23-36 år siden.

Det har tilkommet en bekymringsfull økning i overvekt og fedme de siste tiårene i utviklede land, en tendens som man nå også kan se i utviklingsland. Prevalensen av overvekt er blitt 2-3 doblet de siste år i USA og Europa og den ligger nå mellom 12% og 20% hos barn i alderen 7-11 år i Nord- og Vest-Europeiske land (7, 8, 9). Fedme er et alvorlig helseproblem allerede i barnealder og barneovervekt er relatert til økt morbiditet og mortalitet i voksen alder (10, 11, 12).

Økningen i antall barn med overvekt og fedme viser viktigheten av gode klinisk verktøy for å vurdere overvekt og fedme. Dagens referanser har kun vekt-mot-høyde kurve samtidig som kroppmasseindeks (body mass indeks, kg/m², (KMI)) er blitt internasjonalt anbefalt til bruk for å vurdere graden overvekt og fedme. KMI-kurver for barne- og ungdomspopulasjonen har manglet i Norge, men er nå laget for første gang i regi av Vekststudien i Bergen.

Hensikt

Skaffe informasjon over lengde/høyde og kroppsproporsjoner. Det sistnevnte innebærer målinger av sittehøyde, armspenn, hodeomkrets, underarmslengde og legglengde.
Skaffe informasjon over forekomsten av overvekt og fedme hos norske barn og unge, sammenligne målinger av kroppsmasseindeks (kg/m²), hudfolder og mageomfang.
Skaffe informasjon om tilveksthastighet.
Kartlegge faktorer som kan påvirke vekst- og vektutvikling hos norske barn.
Utforme klinisk relevante prosentil/SD kurver for en rekke vekstparametere.

Materiale og metode

Design

Tverrsnittsundersøkelse for å kartlegge vekst- og vektparametere. Denne ble gjennomført i perioden november 2003 til desember 2006. Følgende målinger ble gjort:
- Lengde/høyde og vekt hos 0-19 år gamle barn
- Hodeomkrets hos 0-15 år gamle barn
- Sittehøyde og mageomfang hos 4-19 år gamle barn
- Armspenn, hudfolder, underarms- og legglengde hos 4-15 år gamle barn
Longitudinell undersøkelse for å kartlegge tilveksthastighet. Omtrent halvparten av barna i alderen 6-18 år ble målt ett år senere – da kun måling av høyde og vekt. Datainnsamlingen ble gjennomført i perioden 2004-2006.
Kartlegging av faktorer som kan påvirke vekst- og vektutvikling. I denne delen av studien utføres en spørreundersøkelse og kobling av dataene opp mot eksisterende databaser. Spørreundersøkelsen ble gjennomført i 2006 og 2007. Svarprosenten var 67%. Spørreundersøkelsen inneholder 38 spørsmål til alle foresatte som hadde barn med alder under 15 år på måletidspunktet.
Utforming av klinisk relevante vekstkurver.

Barnepopulasjonen.

Tverrsnittsundersøkelsen ble gjennomført i perioden november 2003 til desember 2006 da til sammen 8312 barn i alderen 0-19 år ble inkludert og målt. Barna ble rekruttert fra Bergen basert på tilfeldig stratifisert utvelgelse av helsestasjoner (n = 8), barnehager (n = 34) og skoler (n = 24, derav 19 barne- og/eller ungdomsskoler og 5 videregående skoler). Alle barn ble invitert til å delta, men kun barn der det forelå skriftlig samtykke fra foreldrene og/eller barna om deltakelse, ble målt. På helsestasjonene ble rundt 98 % av tilgjengelige barn målt. Deltakelsesprosenten var 57 % i barnehagene, 69 % i barneskolene (1. – 7. skoletrinn), 53 % i ungdomsskolene (8. – 10. trinn) og i de videregående skolene (1. – 3. trinn) 45 %. Deltidsplass i barnehage, aktiviteter i barnehagen eller på skolen måledagen, reiser og sykefravær var alle faktorer som påvirket oppslutningen i tillegg til at noen ikke ønsket å delta.

Målingene (13)

Barna ble målt av helsesøstere ansatt i studien på helsestasjonene, mens barna i barnehagene og på skolene ble målt av studiesykepleiere som arbeidet i team, to og to sammen. Målingene, utført mellom kl. 08.30 og 13.00, ble ført direkte inn på bærbar datamaskin.

Liggende lengde ble målt opp til to års alder med Harpenden Infant Measuring Table®. Barna ble målt uten bleie. Hodet ble holdt av foreldre inntil hodeplaten, således at den nedre orbitakanten lå vertikalt i plan med øreåpningen. Begge bena ble holdt utstrakt av helsesøster, og den flyttbare platen ført opp til fotsålene.

Høyde ble målt stående fra og med to års alder med Holtain Portable Stadiometer®. Barna ble målt avkledd, men med truse og T-skjorte på. Målingen ble utført uten sko og strømper for å se om fotstillingen var riktig og hælene ikke løftet fra gulvet. Barna ble målt med føttene sammen og med hælene, setet og skuldrene inntil måleren. Dersom håret var tykt, ble det lagt et lett trykk på hodeplaten. Barna ble bedt om “å stå rett” og målingen ble tatt i normal respirasjon. Hodestillingen var slik at nedre orbitakant lå i horisontalt plan med øreåpningen.

Vekt ble målt på helsestasjonen uten bleie med digital spebarnsvekt (Seca®). I barnehagene og på skolene ble vekten målt med truse og evt. BH på med digital personvekt (Seca®).

Ved måling av hodeomkrets ble største hodeomkrets målt med måleband av metall (Lufkin®).

Kvalitetskontroll

Ved starten av hver måledag ble måleutstyr, høyde og lengdemålere, kontrollert. Personvekter på helsestasjonene ble kontrollert to ganger årlig og på skolen eller i barnehagen hver gang de ble flyttet (til ny skole/barnehage). To ganger årlig deltok alle målere i felles måleøkt hvor 10 barn ble målt to ganger av alle målere. Målepresisjonen til målere ble vurdert samt variasjonen mellom målere.

Statistiske analyser

Det ble utført beregninger av utvalgsstørrelse på grunnlag av ønsket statistisk styrke. Prosentilkurver ble utarbeidet med LMS-metoden (14). Dataene er for øvrig analysert med programvarene SPSS, STATA og R.

Relevante hovedresultater

Økning i vekt mot høyde hos barn og unge (15)
Blant barna i alderstrinnene 4-16 år er forekomsten av overvekt og fedme 12,5 % og 2,1 % hos guttene, og 14,8 % og 2,9 % hos jentene ( jfr. IOTF-cut-offs). Sammenlignet med tall fra 1970-årene er 8 % av guttene og 7,2 % av jentene over 97,5-prosentilen i vekt-mot-høyde fra 1971-4. Forskjellene er størst i øverste prosentilene, mens de laveste er uforandret. Vekstøkningen rammer derfor stort sett en undergruppe i den norske barnebefolkningen. Studien viser også økning i hudfolder. Kun etnisk norske barn inngikk i denne analysen for å gjøre den sammenlignbar med tallene fra 1970-tallet.
Nye vekstkurver for norske barn i alderen 0-19 år (16)
På grunnlag av datamaterialet fra Vekststudien i Bergen er det utarbeidet nye prosentilkurver for alderen 0-12 måneder (hhv. hodeomkrets, lengde og vekt mot alder), 1-5 år (hhv. hodeomkrets, lengde/høyde og vekt mot alder), 4-19 år (hhv. høyde og vekt mot alder) og 2-19 år (kroppsmasseindeks (KMI) mot alder). På kurvene er det lagt inn grå felt som definerer området mellom median +2,0 til +2,5 standardavvik (s) og området mellom median –2,0 til –2,5 s. På KMI-kurven er det angitt grenseverdier for overvekt, fedme og undervekt. De nye kurvene avspeiler veksten hos dagens norske barnebefolkning og kan erstatte de eksisterende vekstkurver når vekst- og vektutvikling skal følges i primær- eller spesialisthelsetjenesten.
De nye kurvene sammenlignet med eksisterende norske referanse (16)
Dagens barn i alderen 0-4 år har lengde/høyde og vekt som kun er marginalt endret fra eksisterende vekstkurvene. For eldre barn foreligger derimot en økning i 50-prosentilen for høyde med opp til 3,4 cm hos gutter og 2,5 cm hos jenter. For barn over 4 år har vekt i forhold til høyde også økt, og spesielt gjelder dette øverste prosentilene. Sekulære veksttrender gjenspeiler behovet for nye vekstkurver.
De nye kurvene sammenlignet med internasjonale vekstkurver fra WHO for alderen 0-5 år (16)
Kurvene til dagens norske barn ligger over WHO-kurvene for fødselsvekt, lengde/høyde, vekt og hodeomkrets for aldersgruppen 6 mnd til 5 års alder, noe som kan gjenspeile foreskjeller i omgivelsene eller vekstpotensialet mellom populasjonene. Disse forskjellende var framdeles tilstede hos de norske barna som ble brysternærte etter retningslinjene av mødre som ikke røykte. (17)