A Methodology for Evaluating Size at Birth

Abstract

England). A methodology for evaluating size at birth. Acta Paediatr Scand, Suppl. 319 26.Data from the Swedish Medical Birth Registration, 1977-78, were utilized to develop methods of calculating reference standards for evaluating size at birth. Using the clinical information available, a 'healthy' sub-group was extracted. The individual distributions of birthweight (BW), birth length (BL) and birth headcircumference (BHc) at each week of gestational age (GA) were modelled following some truncation of their ranges. Application of the Box-Cox power family of transformations was generally found to improve the normality of the data. Certain percentages (such as 2.28, 50 and 97.72) -re linked through a smoothing dwice. Features of the results include a positively skewed BW distribution in most GA weeks, a normal distribution of BL and BHc at term, a larger relative variation in BW at lower GA than at term, and a distinct sigmoid shape of the median and other BW curves. Compared with flve commonly quoted standards, the present data show the least deceleration in the fullterm region. Disregarding the clinical information, 'primary' sub-groups were also extracted using desomposing techniques. These gave rise to similar BWlGA relationships. Using data from the WHO comparative study, the method just mentioned was applied to standardize BW and BW-specific early neonatal mortality rates. This resulted in an improved description of biological events. Key nwrds: F e d growth, birthweight, birth length, birth head circumference, gestational age, statistical modelling, neonatal mortality, reference standard.

Anthropometry of Malawian live births between 35 and 41 weeks of gestation

“…Twins and stillbirths were excluded from the analysis. Comparison was made with a Swedish reference data set for birth registrations from 1977 to 1978 (Karlberg et al 1985). The Swedish data set was used as this is the only current data set which provides reference values for all three anthropometric measurements (weight, length and head circumference).…”

“…In addition, the Swedish sample excluded babies with stillbirth or serious neonatal disorders, or whose mothers had pregnancy-related disorders such as haemorrhage, cervical insufficiency, urinary infection, eclampsia or pre-eclampsia. Babies whose mothers had syphilis, diabetes, hypertension, heart and kidney disease were also excluded (Karlberg et al 1985).…”

“…The World Health Organization (WHO) has recommended using the Williams Reference (Williams et al 1982, World Health Organization 1995 and previously, Verhoeff et al have used this for analysis of Malawian weight percentiles (Verhoeff et al 1999b (Wilcox 1981, Karlberg et al 1985 or Canadian reference data (Arbuckle et al 1993). In the present analysis, the Swedish reference was used as length and head circumference measurements are available, which are not provided by other data sets.…”

Multiple fetuses, growth deviations and mortality in a very preterm birth cohort

“…If one wishes to evaluate the growth of very preterm infants, several problems emerge. First, the available birth weight charts have been constructed for differently defined newborn populations, and, therefore, exhibit extremely wide normal ranges [4]. Moreover, far too few gestational-week-specific data -in only two reports [1,5] -are available on the birth weights of very preterm infants, particularly of J. Perinat.…”

Sex-Related Differences in School and IQ Performance for Children with Low Birth Weight at Ages 10 and 13

“…The maturity of the LBW children differed at birth; 6 girls and 2 boys were small for gestational age (SGA). SGA was defined as birth weight > 2 SD below the mean birth weight for gestational age according to norm curves (Karlberg et al, 1985). All LBW children born at term and 1 LBW boy born preterm were SGA.…”