Petter Karlberg

An update of the Swedish reference standards for weight, length and head circumference at birth for given gestational age (1977-1981).

ABSTRACT. An update of the Swedish reference standards for weight, length, and head circumference at birth, for each week of gestational age, is presented. It is based on the total Swedish cohorts of infants born 1977‐1981 (n= 475588). A “healthy population” (79%) was extracted, using prospectively collected data. Weekly (28‐42 weeks) grouped data for length and head circumference were well approximated by the normal distribution, but the distributions for birthweight were positively skewed. The original skewed distributions for birthweight were transformed, using the square root, resulting in distributions close to the Gaussian. For smoothing purposes, the weakly values for the mean and the standard deviation were both fitted by a third degree polynomial function. These functions also make possible the calculation of the continuous variable, standard deviation score, for individual newborn infants as well as a comparison of distributions between groups of infants. The reference values and charts presented here have two major advantages over the current Swedish ones: the sample size used is now sufficiently large at the lower gestational ages, so that empirically found variations can be used, and the skewness of the birth weight distribution has been taken into account. The use of the reference standards presented here improves and facilitates evaluation of sue deviation at birth.

Analysis of linear growth using a mathematical model. I. From birth to three years.

ABSTRACT. According to the “ICP‐growth model” (ICP=Infancy, Childhood and Puberty components), linear growth during the first three years of life can be represented mathematically by a combination of a sharply decelerating Infancy component and a slowly decelerating Childhood component. Growth as measured by supine length is analysed for 191 longitudinally followed healthy infants using this model. The main aim is to devise ICP‐based methods for biological and clinical applications. The onset of the Childhood component, which occurs some time between 6 and 12 months of age and is typically abrupt, can be detected on an individual basis. Its starting point probably defines the as yet unknown age at which growth hormone begins to exert a significant influence. The analyses have also revealed some new facets of linear growth. Most infants are found to have a non‐linear decelerating Infancy component, free from seasonal influence. Age at onset of the Childhood component is earlier for girls than for boys and is positively related to the magnitude of the Infancy component. During the second year of life the variation in growth rate of the cohort increases. This fluctuation is found to be seasonal and greater for those with late onset of the Childhood component. During the third year of life the growth pattern is stabilized.

The development of children in a Swedish urban community. A prospective longitudinal study. II. The social background and its changes during the children's first three years of life.

The social conditions of the 212 families participating in the longitudinal study during the childrens first three years of life are described with reference to 23 tables and 2 figures in respect of housing standard, education, occupation and income. The material is classified under each of these variables on a 5‐grade scale in accordance with an international social grouping system (Graffar). The aggregate values of the different variables are considered to reflect the socio‐economic level of the family.

The thermogenic response of the newborn infant to noradrenaline.

The newborn human infant may respond to a change in environmental temperature by an alteration in its heat production [4, 171. This response is a thermoregulatory mechanism, which serves to maintain thermal equilibrium under conditions where control of heat loss is not of itself adequate to do so. Similar thermoregulation has been observed in several animal species [9, 10, 161 and occiirs at temperatures lower than what is termed the neutral zone. It has been suggested [13, 141 that noradrenaline (NAd) could be the mediator by means of which heat production is controlled in the newborn. This substance has also been invoked as the thermogenic hormone in cold adaption in adult rats [6, 7, 11, 121. A direct test of the hypothesis that noradrenaline had this thermogenic action in the human newborn was obviously of great interest and importance, since a better understanding of the control of heat production in the infant could be of considerable clinical value.

Clinical application of evoked electroencephalographic responses in newborn infants. I: Perinatal asphyxia.

Evoked electroencephalographic responses are useful for the study of cerebral maturation in full‐term and pre‐term newborn infants. In an attempt to achieve wider clinical application, 57 newborn infants with differing degrees of perinatal asphyxia were examined. Altogether 154 examinations were performed. In all of them photostimulation was used, and in 72 investigations somatosensory evoked responses were also recorded. The following results were obtained:

Studies of respiratory physiology in the newborn infant. II. Observations during and after respiratory distress.

An invitation to participate in this publication honoring Professor Wallgren confers no small distinction on any American pediatrician. It also imposes a high standard of scientific scholarship upon those so invited. The Harvard group working with newborn infants are more hopeful of meeting that standard because of the recent presence of one of Dr. Wallgrens own staff in our laboratory, a happy circumstance which has considerably increased the information we can contribute to this publication. Although we are submitting only a preliminary report of studies now in progress, the opportunity of presenting the data here was too tempting to be resisted by this international team of admirers of Professor Wallgren, C. A. S.

Weight-for-length model in newborn Swedish infants

A new methodology for evaluation of weight in relation to length normalized for sex and gestational age (leanness/fatness) in the newborn infant is presented. Using standard deviation scores (SDS) for weight and length in a linear regression model, a new continuous variable called LEANSDS has been constructed with intercept = zero, regression coefficient = 0.7152, SD = 0.6988 and r2= 0.51, irrespective of gender and gestational age within the range 34–43 weeks’gestation. The model is based on the Swedish 1986 Medical Birth Register and was tested on the 1985 year cohort. The reference material consisted of live‐born, singleton infants considered “healthy”. This new variable is independent of length. A chart is presented which simplifies visual evaluation. Using — 2 SD as the cut‐off limit, approximately one‐third of light‐for‐dates infants are also lean, while two‐thirds of the lean infants are not light for dates. Proportions of “not healthy” live‐born infants and still births are given. Using another method, based on weight and length, and with some approximations needed for calculation of a comparable BW/BLSDS, the correlation was 0.9974, but this calculation is more elaborate and the comparable chart more complex. This method reveals the influence of gestational age on the relationship between weight and length, indicating a “prenatal puberty”. Empirically, the logarithmic relationship found between weight and length indicates a ponderal index exponent of 2.4–2.5 instead of 3. LEANSDS, with its continuous nature, also gives the degree of deviation in each individual and in groups of infants, and can be added together and further analysed with improved sensitivity.

The development of children in a Swedish urban community. A prospective longitudinal study. I. Introduction, design and aims of the study. Description of the sample.

The first Swedish prospective, longitudinal investigation into the development of children in a Swedish urban community‐is presented. Its aims, design and recruiting procedure are described, and the representativeness of the material obtained is discussed. The investigation forms a link in an internationally coordinated study.

Early affective antecedents of adult Type A behavior.

The early affective, apparently temperamental antecedents of Type A behavior were investigated in a Swedish longitudinal sample (N = 149). Four clusters of Type A items (describing irritability, hurried behavior, work achievement, and competitiveness) were regressed on maternal ratings of the childs poor appetite, sleep disturbances, liveliness, anger, and shyness, collected annually from infancy to adolescence. The childs liveliness, sociability, and poor appetite during infancy and childhood were positively related to the adult Type A irritability and hurried behavior clusters, as were the mothers liveliness, orderliness, and intelligence as rated by psychologists during the childs first 6 years. The two work-involvement clusters were predicted by interactive effects among shyness, poor appetite, and anger during adolescence but were unrelated to mother attributes. Sleep disturbances were only related to competitiveness and only in late adolescence. These findings indicate that the interrelated components of adult Type A behavior have contrasting developmental histories and that temperament-related constructs are important antecedents to the adult syndrome.

The Relation of Stress Hormone Excretion to Type A Behavior and to Health

The relation between catecholamine and cortisol excretion and Type A behavior, assessed using an 11-item self-report questionnaire based on the Jenkins Activity Survey, is examined in a Swedish sample of young adults (N = 149). Cluster analysis indicates that the items measure four aspects of Type A behavior: irritability, hurried behavior, work achievement, and competitiveness. These clusters are not correlated with measures of recent health care utilization. In both sexes, a higher total Type A behavior score is related to decreased daytime urine concentrations of norepinephrine and day and night concentrations of cortisol. In males, increased hurried behavior is related to lower night levels of norepinephrine; higher irritability and competitiveness predict lower night levels of epinephrine and cortisol and increased urine excretion rate. In females, higher irritability and lower competitiveness scores are related to increases in daytime urine excretion and slightly lower levels of cortisol. These results indicate that only certain aspects of the Type A syndrome are related to stress processes and imply that the behaviors serve to lower stress responses in early adulthood.