Johan Karlberg

Swedish population-based longitudinal reference values from birth to 18 years of age for height, weight and head circumference

This study aimed to update growth reference values for height, weight and head circumference in order to reflect the changes in body size in the Swedish population during the past two decades. The data came from a large longitudinal growth study on 3650 full‐term healthy Swedish children who were born between 1973 and 1975. All of these 1801 girls and 1849 boys had longitudinal data for height and weight from birth to final height. Comparison with previous Swedish growth reference values based on children born between 1955 and 1958 revealed that there have been secular changes in body size. For instance, at 18 y of age, the updated height and weight reference values are 180.4 cm for males and 167.7 cm for females, i.e. 1.9 cm taller and 5.7 kg heavier for males and 2.3 cm taller and 3.4kg heavier for females compared with the previous reference values.

BMI in Childhood and Its Association with Height Gain, Timing of Puberty, and Final Height

No large population-based study has addressed the question of how overnutrition is related to subsequent height gain in childhood, timing of puberty, and final height. The present data represent a large Swedish population-based longitudinal growth study. Height gain in childhood, timing of reaching peak height velocity and height gain during adolescence, and final height were regarded as the short-term, interim, and long-term outcomes of childhood nutritional status, i.e. body mass index (BMI) change between 2 and 8 y. Midparental height was adjusted as the genetic influence on linear growth of the child. Childhood BMI gain was related to an increased height gain during the same period, i.e. an increase of 1 BMI unit was associated with an increase in height of 0.23 cm in boys and 0.29 cm in girls. A higher BMI gain in childhood was related to an earlier onset of puberty; the impact on the timing of puberty was 0.6 y in boys and 0.7 y in girls. Each increased unit of BMI gain in childhood also reduced the height gain in adolescence, 0.88 cm for boys and 0.51 cm for girls. No direct correlation was shown between childhood BMI gain and final height. We conclude that overnutrition between 2 and 8 y of age will not be beneficial from a final height point of view, as the temporary increase in height gain in childhood will be compensated by an earlier pubertal maturity and a subnormal height gain in adolescence.

Natural growth in children born small for gestational age with and without catch‐up growth

This first report from a population‐based postnatal growth study of 3650 healthy Swedish subjects born at full term provides new reference values for height and weight and shows that over the last 20 years there has been a small secular trend in height (0.2–0.4 SDS over the whole age range) in Sweden in both boys and girls. Within this cohort, 111 (3.1%) were of low birth weight (below –2 SDS) and 141 (3.5%) were of low birth length (below –2 SDS); 54 (1.5%) were both light and short at birth. Of the children born small for gestational age, 87% showed full catch‐up growth within 2 years of life. They attained puberty at a normal or early age and reached a mean final height of –0.7 SDS. The remaining subgroup of 13% born small for gestational age remained below –2 SDS throughout childhood and reached puberty somewhat early. Their mean final height was –1.7 SDS. The current data set is too small to identify possible background factors, but it is being expanded with this objective in mind.

Quality of life of postmenopausal women on a regimen of transdermal estradiol therapy: A double-blind placebo-controlled study

OBJECTIVE The effect of transdermal estradiol and placebo therapy on the quality of life of postmenopausal women was compared in a randomized trial over 12 weeks. STUDY DESIGN Two hundred forty-two women were randomized, and 223 were analyzed for efficacy (n = 112 for estradiol and n = 111 for placebo). The quality of life was assessed by means of a battery of standard questionnaires. RESULTS Quality of life improved after both therapies, but health-related quality of life (p = 0.0003) and well being (p = 0.003) improved more after transdermal estradiol therapy than after placebo. This was also the case for all specific climacteric aspects, including sexual problems (p < 0.0001) and dysfunction (p = 0.01), at comparison with placebo. Self-rated symptom relief was more pronounced with estrogen therapy than with placebo (p < 0.0001). CONCLUSION It was concluded that estradiol therapy was superior to placebo in relieving symptoms and improving quality of life.

Secular trends in pubertal development.

Objective: To describe the secular trend in pubertal development in relation to the secular trend in height. Methods: Literature review of cross-sectional, longitudinal and twin studies. Results: Globally, there is a secular trend in adolescent growth for an increased mean final height at adulthood. To a lesser extent, there is also a secular trend towards earlier puberty. However, it seems that the two trends are not strongly connected. The increase in average height over the generations can, to a large extent, be explained by an earlier onset of the growth hormone-dependent phase of growth in early life. The age when this growth ‘spurt’ occurs in childhood strongly correlates with final height, but is not related to the age at peak height velocity during puberty. There is a large variation in the timing of the onset of puberty; it is largely influenced genetically, as implied by studies in twins. The single environmental factor that stands out as most significant – possibly explaining as much as 25% of the variation in the timing of puberty – is simply nutritional status in childhood; overnutrition and obesity seem to trigger pubertal onset. However, recent studies have identified that both shortness and thinness at birth are also associated with earlier pubertal maturation – a reverse of their impact during childhood years. Conclusions: More longitudinal studies are needed to understand the short- and long-term consequences of secular changes in both final height and pubertal development before we know how important the trends are.

Body mass index reference values (mean and SD) for Swedish children

Body mass index (BMI) is an important indicator of nutritional status. Many studies have been done to present BMI reference values in centile values rather than mean and SD values since its statistical distribution is positively skewed. Both height and weight growth charts are usually available in terms of mean and 1, 2 and 3 SD around the means; it would be of clinical value to produce BMI reference charts in a similar way. The aim of this work was to derive the mean and ±1, 2 and 3 SD BMI reference ranges as a supplement to the BMI centile reference values published previously for the same group of Swedish children. The method was based on an age‐dependent Box transformation, and the β‐value was given as a third‐degree polynomial function over the paediatric age. The BMI reference values can be given from mathematical functions in addition to values for specific ages.

Blood Pressure Is Associated With Body Mass Index in Both Normal and Obese Children

Obesity is associated with elevated blood pressure (BP) both in adults and children. Childhood obesity has become a severe health problem, especially during the last few decades. So far there has not been any large-scale study specifically focusing on the association between obesity and BP in early life. The aim of this study is to examine systematically the association between obesity and BP in preschool Chinese children in mainland China. In 1996, measurements of weight, height, and BP values were collected in a nationwide, case-control study of 748 boys and 574 girls who ranged in age from 0.1 to 6.9 years in 8 cities in mainland China. One obese child and 1 nonobese child were matched for gender and age. The BP differences of the mean-matched pair were approximately 5 mm Hg for systolic blood pressure (SBP) and approximately 4 mm Hg for diastolic blood pressure (DBP) (P<0.05); a higher value was noted in obese children. The BP value of 19.4% children in the obese group and 7.0% children in the nonobese group was higher than the 95th percentile value (P<0.0001), which is defined as high BP by the Task Force on Blood Pressure Control in Children. Both SBP and DBP were significantly (P<0.05) positively related to body mass index (BMI) values (P<0.05) for children in obese and nonobese groups after adjustment for age, gender, and height. To be specific, an increase of 1 BMI unit was associated with, on average, an increase of 0.56 mm Hg and 0.54 mm Hg in SBP and DBP, respectively, for obese children. In nonobese children, the increase in SBP and DBP was 1.22 mm Hg and 1.20 mm Hg, respectively. An increase in the BMI is conclusively associated with elevated SBP and DBP in nonobese children. Furthermore, an increase in the adjusted BMI was associated with an increase in SBP and DBP in obese and nonobese children.

Children born small-for-gestational age: Postnatal growth and hormonal status

It is generally recognized that children born small-for-gestational age (SGA) have a 5–7 times higher risk of short stature than children born at normal size. It has been suggested that the programming of the endocrine axes occurs during critical phases of fetal development and is affected by intrauterine growth retardation. This study was undertaken to characterize the postnatal growth pattern and the final height of children born SGA, as part of a population- based study (n = 3,650), from birth to final height, and to evaluate the hormonal status in another group of prepubertal children born SGA (n = 134) without postnatal catch-up growth. The majority (88%) of ‘healthy’ full-term singleton SGA infants achieved catch-up growth during the first 2 years of life, and most of the increase in height occurred by 2 months of age. The SGA children who remained short at 2 years of age had a higher risk of short stature later in life. The risk of having a short final height (<–2 SDS) was five times higher for children with a low birth weight and seven times higher for those with a low birth length in comparison with children with a normal birth size. Moreover, about 20% of all children of short stature were born SGA. As a group, children born SGA will have a final height, expressed in SDS, as they had during the prepubertal years. This is in contrast to children, who became short postnatally. During puberty, these short children will have a mean height gain of 0.6 SDS for girls and 0.7 SDS for boys. The mean estimated secretion rate for growth hormone (GH) was lower in the short children born SGA compared with the reference groups born at an appropriate size for gestational age, of either short (p < 0.05) or normal stature (p < 0.001). Moreover, in the youngest children born SGA (2–6 years of age) a different pattern of GH secretion was found, with a high basal GH level, low peak amplitude, and high peak frequency. The majority of the children born SGA had levels of GH-binding protein within the range previously reported for normal children. However, the levels of insulin-like growth factor I (IGF-I), IGF-binding protein-3 (IGFBP-3) and leptin were significantly reduced compared with the reference values (p < 0.001, p < 0.01 and p < 0.001, respectively). In conclusion, the low spontaneous GH secretion rate and a disturbed GH secretion pattern, together with low serum levels of IGF-I, IGFBP-3 and leptin, might contribute to the reduced postnatal growth in some of the subgroup of children born SGA who remained short during childhood.

Population-based body mass index reference values from Göteborg, Sweden: birth to 18 years of age.

The body mass index or BMI (weight/height2) is a somewhat crude estimate of nutritional status. However, due to its simplicity and high correlation with total body fat, it has been the method of choice in both paediatric clinics and research over the years. Since BMI is not an equivalent measure of the percentage of body fat in different ethnic groups and in the two sexes, population‐specific BMI reference data is needed. Several BMI reference values have been published for French, American, British and Hong Kong children in recent years. In Sweden, weight‐for‐age and height‐for‐age reference values, which were published in 1976, are still used as the current national growth reference values. Updated growth reference values are needed for assessing nutritional status due to the secular trend toward and increasing prevalence of childhood obesity. The aim of this study was to produce BMI reference values for Swedish children of paediatric age. The series came from a large Swedish population‐based longitudinal growth study of 3650 full‐term babies followed from birth to 18 y of age. The children in this data set were born in the early 1970s. The pattern and level of 50th centile BMI values presented here are quite similar to those of the Swedish cohort study in the 1950s. In comparison with the US BMI reference values, the Swedish values are much lower, especially for the higher centile values.

The timing of early postnatal catch-up growth in normal, full-term infants born short for gestational age

Postnatal catch-up growth in infants born small for gestational age has been reported to occur mainly during the initial 3-9 months of life. The study presented here characterized early postnatal growth in healthy, full-term infants born short for gestational age (GA) (< -2 standard deviation scores [SDS] in birth length) in two populations. Results from a longitudinal growth study from birth to final height of 139 infants born short for GA between 1973 and 1975 in Göteborg, Sweden, were compared with results from an ongoing detailed prospective 6-month follow-up of 41 Hong Kong Chinese infants born short for GA in 1995 and 1996. For both populations, height was expressed in SDS using the updated Swedish growth reference data at birth and postnatally. In the Swedish study, 92% of the children born short for GA reached a final height greater than -2 SDS; 76% had a height greater than -2 SDS by 2 months of age. In the Hong Kong study, 79% reached a height greater than -2 SDS by 5 months of age (the longest follow-up time to date). A third population of Hong Kong Chinese infants born short for GA in 1967 was studied; 65% had reached the normal height range by 5 months of age. In the later Hong Kong study (1995-1996), catch-up growth could be identified as early as 12 weeks of age, which has important implications for clinical practice. Thus, growth monitoring during the first weeks of postnatal life gives useful information on catch-up growth in infants born short for GA.