'Birth to Ten'--pilot studies to test the feasibility of a birth cohort study investigating the effects of urbanisation in South Africa

'Birth to Ten' is a birth cohort study currently being conducted in the Johannesburg-Soweto area. This paper describes the various pilot studies that were undertaken to investigate the feasibility of a cohort study in an urban area. These studies were designed to determine the monthly birth rate, the timing, frequency and duration of maternal antenatal visits, the timing and frequency of visits to well-baby clinics and the accuracy and reliability of routinely collected growth data. In addition, a birth data collection form was tested to ascertain the appropriateness of its use in clinics within the study area.

Missed opportunities for measles immunisation in selected western Cape hospitals

Measles is still a major cause of childhood mortality and morbidity in South Africa. The World Health Organisation (WHO) has recently recommended that greater attention be paid to opportunities for immunisation in the curative sector. This study quantified the extent of missed opportunities for measles immunisation in children attending primary, secondary and tertiary level curative hospitals in the western Cape. Exit interviews of 1,068 carers of children aged between 6 and 59 months inclusive showed that 2.4-40.7% of carers had been requested to produce a Road-to-Health card, and that 4.8-43.1% of carers had a card available. The proportion of children with documented evidence of measles immunisation available ranged from 4.8% to 40.0% between facilities. The study demonstrated that a considerable number of potential opportunities to immunise children against measles are currently being missed in children attending hospitals and day hospitals in the western Cape. The study documents the effect of a fragmented approach to health care, and indicates a need for rapid integration of preventive and curative components of health care into a metropolitan-based primary health care service.

Birth to ten: child health in South Africa in the 1990s. Rationale and methods of a birth cohort study

Birth to Ten is a longitudinal birth cohort study which began in April 1990 in the Johannesburg/Soweto area of Transvaal, South Africa. In this paper, the reason for the initiation of the study and its location in the current sociopolitical context is discussed. The health status of South Africa children in terms of infant mortality, morbidity (notifiable diseases) and nutritional status is described and mention is made of measures of psychological health and the importance of environmental pollution on health. The existing health service infrastructure in the study area is described and the fragmentation of health services between races, between preventive and curative services and on a geographical basis is highlighted. The study objectives, design, population, inclusion and exclusion criteria, methods of measurement and logistics are described.

The start of breast development and age at menarche in South African black females

Age at the start of breast development and at menarche are important maturity indicators in adolescent females. Breast development is usually the first event of puberty and menarche virtually the last. Irregularities in the age of the subject at their appearance can denote a lack of synchronisation between pubertal events, which, in turn, may indicate hormonal or psychosocial disturbance. Data are presented on the age of occurrence of breast development, according to Tanner's criteria, and age at menarche for urban and rural South African black females. In addition published reports are reviewed to determine whether there is a pattern of change in these ages. Breast development seems to be fairly stable, occurring in girls between the ages of 10.5 years and 11.5 years. Age at menarche appears to have decreased over the last 40 years in children from both urban and rural environments. Girls from rural areas have a delay of about 1.5 years in both pubertal events.

Measurement error in human dental mensuration

The reliability of human odontometric data was evaluated in a sample of 60 teeth. Three observers, using their own instruments and the same definition of the mesiodistal and buccolingual dimensions were asked to repeat their measurements after 2 months. Precision, or repeatability, was analysed by means of Pearsonian correlation coefficients and mean absolute error values. Accuracy, or the absence of bias, was evaluated by means of Bland-Altman procedures and attendant Student t-tests, and also by an ANOVA procedure. The present investigation suggests that odontometric data have a high interobserver error component. Mesiodistal dimensions show greater imprecision and bias than buccolingual measurements. The results of the ANOVA suggest that bias is the result of interobserver error and is not due to the time between repeated measurements.

Secondary sexual development of Cape coloured boys following kwashiorkor

This report describes the secondary sexual development of 78 Cape Coloured male ex-kwashiorkor patients and 53 male controls. All patients were originally seen between 5 months and 4 years 4 months of age, treated and then followed up for 15 years after discharge. Age at peak height velocity (PHV) was available for 23 ex-patients and 15 controls. Maximum likelihood estimates of the mean age at entry to each pubertal stage were made and age at PHV was obtained by fitting a non-linear growth function to the data for each subject with appropriate serial height records. No significant differences were observed between ex-patients and controls for either the sequence of pubertal events or for the age of entry to each stage. When compared to a sample of normal British boys the Cape Coloured sample exhibited significant delay for ages at entry to all pubertal stages with differences ranging from 0.84 years for PH2 to 1.94 years for PH5. It is suggested that adrenal androgens play a major role in delaying secondary sexual development during chronic malnutrition and that the anterior pituitary's response to such conditions is to selectively delay pubertal status.

Fast to slow phenotypic changes in rabbit muscle can be induced without increases in neural activity

Immobilization of rabbit tibialis anterior (fast) muscle in a lengthened position for 5 weeks led to a fivefold increase in the number of slow oxidative fibres. Unlike the situation in other models of phenotypic change in adult muscle, the increased expression of slow phenotype was not associated with an increase in the level of electrical activation, as monitored in the stretched muscles by chronic telemetric electromyography.

Recovery from immobilization-induced atrophy of rabbit soleus muscles can be accelerated by chronic low-frequency stimulation

Immobilization of rabbit soleus muscles with an ankle joint angle of 90 degrees led to gross degeneration after 2 weeks. Natural recovery in the subsequent 2 weeks had little effect on the mean area of soleus fibres, although there were signs of regeneration. However chronic low-frequency activation of soleus muscles by nerve stimulation greatly accelerated recovery, producing muscle fibres of normal areas and with characteristics of maturity.

A critical assessment of the width coefficient, K, as an indicator of nutritional status

The width coefficient, K, was assessed critically to examine its underlying assumptions, its relationship to absolute dimensions of body size, and its ability to identify children classified as malnourished by internationally accepted criteria. The scientific integrity of the formula to calculate K depended on the assumption that the body could be viewed as a cylinder with a density of 1.0 g/ml. The empirical testing of the former assumption showed that the body could not be viewed as a cylinder and papers describing body density suggest that age and sex dependency militate against the acceptance of an age- and sex-independent value of 1.0 g/ml. As an indicator of nutritional status K performed well in that it identified children below 75% of weight for age, but it could only identify 47% of children below 90% weight for height. The relative complexity of its calculation and interpretation militate against the use of K as an indicator of malnutrition for the general health worker, but its ability to identify moderately malnourished children by weight for age gives it credibility in the absence of an age assessment.

Secondary sexual development of 'Cape Coloured' girls following kwashiorkor

This report describes the secondary sexual development of 45 'Cape Coloured' female ex-kwashiorkor patients and 43 female controls. All patients were originally seen between five months and four years four months of age, treated and then followed up for 15 years after discharge. Age at menarche was available on 42 ex-patients and 33 controls, and age at peak height velocity (PHV) was available for 30 ex-patients and 15 controls. Maximum likelihood estimates of the mean age at entry to each pubertal stage were made, age at menarche was obtained directly from the subject records and age at PHV was obtained by fitting a non-linear growth function to the data for each subject. All subjects passed through the sequence of pubertal events in the normal order, i.e., no reversals were observed. Ex-patients were generally delayed in relation to controls but there were no significant differences for ages at entry to any of the pubertal stages. The subjects were combined for comparison to equivalent data on British girls. The South African girls were significantly delayed in the development of pubic hair and menarche but showed no significant differences for age at entry or duration of breast development and PHV. It is suggested that lack of delay in breast development may have selective advantages to females living in situations of chronic malnutrition.

Evidence for a secular trend in the Negro dentition

Metric changes in the Negro dentition were evaluated in a sample of artificial stone casts of the dental arcades of 106 living South African Negroes (56 males, 50 females) and in 100 Negro crania (50 males, 50 females) drawn from the R. A. Dart Collection. Comparison of the mesiodistal and buccolingual dimensions of these two samples to the published results of a similar study on earlier Negroes revealed a statistically significant trend towards tooth-size enlargement. This positive secular trend was found to be most pronounced in the mesiodistal diameter, with less than half of the teeth considered showing significant buccolingual enlargement. Although the trend was equally pronounced in both sexes and in both arcades, mesiodistal change was found to increase in an antero-posterior direction, while buccolingual change centred around the anterior teeth.

Standards for human growth--their construction and use

Human growth charts are used in the RSA to monitor the growth of groups of children and of individuals. Ignorance of their construction leads to misunderstandings of their correct application. The construction and use of growth charts is reviewed by explaining how growth may be investigated through cross-sectional, longitudinal and mixed-longitudinal studies and the problems involved in using the subsequent data. The intellectual confusion brought about by describing such charts as 'standards' and how the most appropriate chart for South Africa should be defined is also discussed. Finally, the priorities for research in this field are outlined.

Timing and magnitude of adolescent growth in height and weight in Cape coloured children after kwashiorkor

One hundred sixteen patients who had had kwashiorkor between the ages of 5 months and 4 4/12 years and 89 controls were the subjects of a 15-year follow-up study of their growth and development. We report the findings of a longitudinal analysis of 53 (30 females) of the ex-patients and 30 (15 females) of the controls, selected because at the end of 15 years of study they conformed to the criteria of adult secondary sexual characteristics, height velocity less than 2 cm/yr, and completeness of data. Nonlinear curve-fitting techniques were applied to the height and weight data for these subjects using the Preece-Baines model 1 growth function to determine the timing and magnitude of adolescent growth spurts and the associated biologic changes. Both ex-patients and controls grew below the 25th percentile of British longitudinal standards, but the male ex-patients were heavier, and perhaps taller, than the controls for most of their childhood and adolescence. Velocity curves indicated that the ex-patients had higher pre-adolescent peak increments than the controls and a generally longer growth spurt of reduced magnitude. Two possible explanations are discussed: Garrow and Pike's theory that children with kwashiorkor have a genetic potential for greater physical growth, and a socioeconomic crisis occurring within a family affects the youngest child, who subsequently requires a longer time to recover than do siblings within an improving socioeconomic situation.

The application of new height-prediction equations (Tanner-Whitehouse mark 2) to a sample of Canadian boys

The adult statures of a sample of 71 Canadian boys from the Saskatchewan Longitudinal Growth Study were predicted using the original TW Mark 1 and the new TW Mark 2 prediction equations. The subjects had a mean chronological age of 11.59 years (SD = 0.30), a mean RUS bone age of 11.62 'years' (SD = 1.18), a mean height of 145.0 cm (SD = 6.98) and a mean measured adult height of 177.2 cm (SD = 6.65). The Mark 2 equations improved the predictions over Mark 1 by an average of 0.2-0.6 cm and slightly reduced the range of errors. No improvement in the prediction of boys above the 75th centile of British standards was noted but 60-70% of boys below the 25th centile predicted better with the Mark 2 equations. This pattern may well be repeated in more extreme subjects. About 80% of individuals who predicted badly with the Mark 1 equations, i.e. with errors equal to or greater than 5 cm, improved their predictions when Mark 2 equations were used.

Prediction of adult height from height and bone age in childhood. A new system of equations (TW Mark II) based on a sample including very tall and very short children

A new series of equations is presented for predicting the adult height of a child given present height and bone age. These equations (TW height prediction, Mark II) which replace the ones given in 1975 (TW height prediction, Mark I) are based on larger numbers of normal children, and more importantly on a sample that includes, for the first time, numbers of very tall, very short, and very growth-delayed children. In addition, equations are given for use when the increment of height or bone age, or both, over the previous year is known. These variates improve the prediction at most ages over 8 years in girls and 11 years in boys. The previously given parental allowance has been dropped. Typically 95% of the predictions lie within +/- 8 cm of the real value for boys aged 10 years, falling to +/- 6 cm for boys aged 15 years, or +/- 4 cm if their previous height increment is known. For premenarcheal girls the predictions lie within about +/- 6 cm at age 8 years; a figure which diminishes little till 13 years unless height and bone age increments are known, when it reaches +/- 4 cm at 13 years. For postmenarcheal girls the predictions are substantially more accurate.