Mothers' judgements about their child's weight: distinguishing facts from values

BACKGROUND

Mothers' responses to questionnaire items assessing their child's weight status typically do not correspond to conventional clinical classifications based on body mass index (BMI). From this observation health professionals infer that mothers do not recognize overweight in their child. But the questions used have generally confounded factual judgements with values, so it is not clear whether the mothers are making factual errors, or differ from professionals in their values.

METHODS

Cross-sectional study of population-based birth cohort at 6-8 years and their mothers (n = 540). An objective BMI matching task was used to determine the accuracy of mothers' recognition of their child's weight. Mothers matched their child to sex- and age-specific images of children of known BMI ranging from very thin to obese, and chose a descriptor of their child's weight of the kind used in previous research.

RESULTS

Mothers tended to underestimate their child's BMI on the matching task. Matching errors significantly predicted mothers' description of their child's weight; those who overestimated their child's BMI on the matching task were more likely to say their child was overweight, while those who underestimated it were less likely to, independently of their child's actual BMI.

CONCLUSIONS

Educational programmes aimed at parents of young primary school children need to address separately the factual and the evaluative components of their assessment of child weight.

When do mothers think their child is overweight?

OBJECTIVE

To quantify how overweight children have to be for their mothers to classify them as overweight and to express concern about future overweight, and to investigate the adiposity cues in children that mothers respond to.

DESIGN

Cross-sectional.

SUBJECTS

A total of 531 children from the Gateshead Millennium Study cohort at 6-8 years and their mothers.

MEASUREMENTS

In the mother: responses to two questions concerning the child's adiposity; height; weight; educational qualifications; and economic status. In the child: height; weight; waist circumference; skinfold thicknesses; bioelectrical impedance; and bone frame measurements.

RESULTS

The body mass index (BMI) at which half the mothers classify their child as overweight was 21.3 (in the obese range for children of this age). The BMI at which half the mothers were concerned about their child becoming overweight in the future was 17.1 (below the overweight range). Waist circumference and skinfolds contributed most to mothers' responses. Although BMI and fat scores were important predictors individually, they did not contribute independently once waist circumference and skinfolds (their most visible manifestations) were included in the regression equations. Mothers were less likely to classify girls as overweight. Mothers with higher BMIs were less likely to classify their child as overweight, but were more likely to be concerned about future overweight.

CONCLUSION

Health promotion efforts directed at parents of young primary school children might better capitalise on their concern about future overweight in their child than on current weight status, and focus on mothers' response to more visible characteristics than the BMI.

The detection of early weight faltering at the 6-8-week check and its association with family factors, feeding and behavioural development

AIMS

To identify infants with early weight faltering at the 6-8-week check and examine their family circumstances, feeding and behavioural development.

METHODS

Over a 2-year period, the weight gain of all infants born in an area of North East England was screened. z Scores for weights at birth and at 6-8 weeks were used to calculate a "thrive index" (z score for weight gain). In a nested case-control study within the larger cohort, infants below the fifth centile on the thrive index were identified. 74 cases and 86 controls were followed up. Their development was assessed at 4 and 9 months using the Bayley Scales and their mothers interviewed.

RESULTS

Of 1996 infants, weights at birth and at 6-8 weeks were available for 1880 (94%), and 6.1% of term-born infants were identified as weight faltering over the first 6-8 weeks. These infants had more feeding problems and showed some developmental delay as assessed using the Bayley Scales (at 4 months, mean difference and 95% CI -3.5, -0.6 to -6.4 for the Mental Developmental Index (MDI) and -3.6, -0.2 to - 6.9 for the Psychomotor Developmental Index (PDI); at 9 months -2.3, 1.3 to -5.8 for MDI and -2.2, 2.5 to -7.0 for PDI). Their families were not significantly different from those of controls on any economic or educational measure.

CONCLUSION

Infants whose early weight gain is slow show more feeding problems than controls, and some developmental delay. They can be identified using a thrive index at the 6-8-week check.

The social facilitation of food intake

Perspective on the paper by Lumeng and Hillman (see page 384)

Physical and emotional development, appetite and body image in adolescents who failed to thrive as infants

BACKGROUND

Previous studies suggest that failure to thrive in infancy may be associated with adverse sequelae in childhood. Although cognitive abilities have been extensively investigated, little systematic research is available on other aspects of development.

METHODS

Eighty-nine children who failed to thrive as infants and 91 controls were followed up when twelve years old and examined using anthropometric measurement, self-ratings of appetite and body image, the Dutch Eating Behaviour Questionnaire, the Self-perception Profile for Children, The Revised Children's Manifest Anxiety Scale, the parent and child form of the Mood and Feelings Questionnaire and the parent and teacher's form of the Child Behavior Checklist.

RESULTS

The children who failed to thrive were significantly shorter and lighter at twelve and had significantly lower BMIs, but they did not go into puberty any later. They were more likely to rate their appetite as lower than their best friend's, were generally more satisfied with their body shape, and had significantly lower restraint score on the Dutch Eating Behaviour Questionnaire. They were not significantly different from controls on any of the measures reflecting anxiety, depression or low self-esteem.

CONCLUSIONS

Failure to thrive in infancy is not associated with adverse emotional development in childhood.

The influence of maternal socioeconomic and emotional factors on infant weight gain and weight faltering (failure to thrive): data from a prospective birth cohort

AIMS

To study the influence of maternal socioeconomic and emotional factors on infant weight gain and weight faltering (failure to thrive) in the first year of life.

METHODS

The Gateshead Millennium Baby Study is a population birth cohort in northeast England studied prospectively from birth, via parental questionnaires and a health check aged 13 months. Data were collected on maternal education, deprivation, eating attitudes, and depression, using the Edinburgh Post Natal Depression Scale (EPDS) at 3 months. Weight gain was assessed using change in weight SD score, conditional on birth weight (Thrive Index); weight faltering was defined as conditional weight gain below the 5th centile.

RESULTS

Of 923 eligible infants born at term, 774 (84%) had both weight and questionnaire data. Replicating a previous finding, both the highest and the lowest levels of deprivation were associated with weight faltering; this was independent of the type of milk feeding. No relation was found with maternal educational status. Maternal eating restraint was unrelated to weight gain. Infants of mothers with high depression symptom scores (EPDS >12) had significantly slower weight gain and increased rates of weight faltering up to 4 months (relative risk 2.5), especially if they came from deprived families, but by 12 months they were no different from the remainder of the cohort.

CONCLUSIONS

In this setting, social and maternal characteristics had little influence on infants' weight gain, apart from a strong, but transient effect of postnatal depression.

Why are babies weaned early? Data from a prospective population based cohort study

BACKGROUND

The recommended age of introduction of solids food to the diet of infants (weaning) has recently been increased in the UK to 6 months, but most babies are still weaned before the age of 4 months.

AIMS

To examine what predicts the age of weaning and how this relates to weight gain and morbidity using data from a population based cohort.

METHODS

Parents of 923 term infants born in a defined geographical area and recruited shortly after birth were studied prospectively using postal questionnaires, weaning diaries, and routinely collected weights, of whom 707 (77%) returned data on weaning.

RESULTS

The median age of first weaning solids was 3.5 months, with 21% commencing before 3 months and only 6% after 4 months of age. Infants progressed quickly to regular solids with few reported difficulties, even when weaned early. Most parents did not perceive professional advice or written materials to be a major influence. The strongest independent predictors of earlier age at weaning were rapid weight gain to age 6 weeks, lower socioeconomic status, the parents' perception that their baby was hungry, and feeding mode. Weight gain after 6 weeks was unrelated to age of weaning. Babies weaned before 3 months, compared to after 4 months, had an increased risk of diarrhoea.

CONCLUSIONS

Social factors had some influence on when weaning solids were introduced, but the great majority of all infants were established on solids before the previously recommended age of 4 months, without difficulty. Earlier weaning was associated with an increased rate of minor morbidity.

Low cord ghrelin levels in term infants are associated with slow weight gain over the first 3 months of life

Lower ghrelin levels have been related to slower growth in small for gestational age infants, and infants with higher cord leptin levels have been reported to gain weight more slowly from birth to 2 yr. This study investigated whether cord blood ghrelin and leptin levels are related to weight gain up to 12 wk of age. One hundred infants were weighed at birth and at 12 wk, and cord blood was assayed for ghrelin and leptin. The mean (+/-sd) birth weight was 3.458 (0.433) kg (median, 3.390; range, 2.510-4.615 kg). The mean (+/-sd) leptin level was 10.1 (6.7) ng/ml (median, 8.4; range, 1.6-36.7 ng/ml), and that of ghrelin was 760.9 (282.9) pg/ml (median, 770; range, 210-1670 pg/ml). Higher birth weight was associated with slower weight gain. Leptin was correlated with birth weight, but ghrelin was not, and leptin and ghrelin levels were not significantly correlated with one another. With birth weight as a control variable, ghrelin was significantly associated with slow weight gain (chi(2) = 7.20 with 1 df; P < 0.01), although leptin was not (chi(2) = 1.59 with 1 df; P > 0.1). In conclusion, lower cord ghrelin levels are associated with slower weight gain from birth to 3 months of age.

Family, socioeconomic and prenatal factors associated with failure to thrive in the Avon Longitudinal Study of Parents and Children (ALSPAC)

BACKGROUND

The epidemiological profile of infants failing to thrive is unclear. The aim of this study is to investigate the prenatal and socioeconomic factors associated with these infants using standardized weight gain conditional on previous weight.

METHODS

In a large UK population cohort study, 11 718 infants born at term in 1991-1992 with no major congenital abnormalities were identified. Using a weight gain criterion conditional on initial weight from birth to 6-8 weeks, 6-8 weeks to 9 months, and birth to 9 months, the slowest gaining 5% were identified.

RESULTS

None of the prenatal factors was associated with failure to thrive in the multivariable analysis nor were traditional markers of socioeconomic deprivation such as poor parental education or low occupational status. Parental height was significantly correlated with slow infant weight gain in both separate periods and from birth to 9 months (Pearson's r = +0.20, P < 0.001). Eight times as many infants born to shorter parents (8.7%, 95% CI: 6.6, 11.3) showed slow weight gain as infants born to taller parents (1.1%, 95% CI: 0.5, 2.5). Higher parity was also related to slow infant weight gain; infants born in the fourth or subsequent pregnancy were twice as likely to fail to thrive from birth to 9 months (8.3%, 95% CI: 6.4, 10.6) as first-born infants (3.4%, 95% CI: 2.9, 10.6).

CONCLUSIONS

Future studies need to take account of parental height when calculating growth standards and look at why failure to thrive is more common, not in poorer families but in larger families.

To what extent is failure to thrive in infancy associated with poorer cognitive development? A review and meta-analysis

BACKGROUND

Previous empirical studies of the cognitive sequelae of failure to thrive in infancy have led to apparently inconsistent conclusions.

METHODS

Studies of cognitive abilities in failure to thrive were located through published bibliographies, supplemented by a search through MEDLINE. They were classified (a) into those in which the cases were identified in hospital or other specialist clinics, and those in which they were identified in primary care or by whole population screening; (b) into those that were controlled and those that were not controlled; and (c) into those with a cross-sectional and those with a longitudinal design. Effect sizes in controlled studies were summarised using D statistics for the principal cognitive outcome measure, from the last occasion on which the child was tested if the study was longitudinal.

RESULTS

In studies with cases identified in hospital or other specialist clinics (52 cases, 36 controls), the pooled effect size (weighted standardised mean difference) for cognitive outcomes was -.85 (95% CI -.41 to -1.30). In studies with cases identified in primary care (552 cases, 573 controls), it was -.30 (95% CI -.18 to -.42). In each longitudinal study testing the same children at different ages, the effect size was smaller when the children were older. To obtain an overall estimate of the long-term cognitive outcome of failure to thrive in infancy, data from controlled studies in which cases were identified in primary care, and restricted to IQ or McCarthy scale scores in older children (502 cases, 523 controls), were used. The weighted mean difference was -.28 (95% CI -.16 to -.41), equivalent to 4.2 IQ points (95% CI 2 to 6).

CONCLUSIONS

Evidence from reasonably well-controlled studies indicates that failure to thrive in infancy is associated with adverse intellectual outcomes sufficiently large to be of importance at a population level.

Feeding behaviour in the weaning period

Feeding behaviour in the weaning period is important theoretically and practically. The aim of the study was to develop appropriate observational codes for its description, to assess their reliability, and to examine the relationships between feeding behaviour, meal duration, and food intake. One hundred children aged 12-14 months were visited in their own homes, and two of each child's usual meals video-recorded and analysed using direct observation. Codes were developed that distinguished between the mother feeding her child directly and assisting her child's self-feeding, and between the child's behaviour when responding to being fed by the mother and when feeding themselves. All-occurrence sampling was used to record counts of these feeding acts during the meals. Two observers replicated coding of 40 randomly chosen meals to determine the reliability of these counts. Except for three codes which were used very infrequently (median counts of zero over the 200 meals), reliability was high with p > .80. There was wide variation in the extent to which individual children fed themselves during meals, with only moderate consistency from meal to meal. Food intake was uncorrelated with meal duration, but correlated with the number of bites of food taken. Adjusted for the number of bites, longer meals were associated with a lower intake. When fed by the mother the child's food intake was greater than when they fed themselves, but the duration of the meals was little affected. The coding scheme is simple to use and generally reliable, and provides a means for relating more global measures of emotional or other characteristics of mealtime behaviour to feeding behaviour and nutritional intake.

Energy intake, appetite and body mass in infancy

Energy intake in infancy depends on the infant's appetite, which, in turn, depends to a considerable extent on the infant's size, as size is an important determinant of energy expenditure. Previous work on six-week old breast-fed infants has suggested that, at this age, milk intake in infants is proportional to the square root of body weight (wt.(0.5)). In this paper, the form of the relationship between body weight and energy intake is examined in infants of different ages, using data from two longitudinal studies, one of initially breast-fed and one of initially bottle-fed infants. In the first data set, energy intake is proportional to body weight raised to powers ranging from 0.63 to 1.23 at different ages and, in the second, to body weight raised to powers ranging from 0.50 to 1.07 at different ages. No single value is consistent with all the data at all ages. In general, the powers decrease up to six months of age, and then increase again, a pattern that may be due to the pattern of changes in the adiposity of the infants, as reflected in their body mass indexes (BMIs).

Effects of parity on breastfeeding: a study in the rural setting in northern Thailand

This analysis was undertaken to see whether or not previous successful breastfeeding has any influence on subsequent breastfeeding behavior. Lactational outcomes were compared between those with and without breastfeeding experience.

METHODS

Amount of breast milk transferred, frequency of breastfeeding, and time spent on the breast, as well as infant's weight, were recorded on days 15, 45, 90, 180, 270, and 360 postpartum in 30 primiparae and 30 multiparae. Outcomes of the primiparae were found to be similar to those of the more experienced breastfeeding multiparous mothers with respect to infant growth, amount of breast milk transferred, and the frequency of breastfeeding or number of attachments to the breast. Though primiparae took somewhat longer to transfer similar amounts of breast milk to their infants during the initial 45 to 90 days postpartum, feed duration after 90 days was similar to that of the multiparae. Lactation performance of the rural northern Thai mothers in our sample was highly successful with or without previous breastfeeding experience. It may be that a cultural pattern of breastfeeding on demand, strong family support, and traditional practices that encourage close contact between mother and her newborn compensate for the absence of lactational experience. Unlike reports from Western countries, previous breastfeeding does not appear to be an important predictor of successful and prolonged breastfeeding in our population.

Cognitive and educational attainments at school age of children who failed to thrive in infancy: a population-based study

A 1-year cohort of children born at term in Newcastle-upon-Tyne in 1987/8 was screened for failure to thrive in infancy using a conditional longitudinal standard which identified those whose weight gain was in the lowest 5%. A group of 136 cases and 136 controls (from the same GP practice and living in a neighbourhood with the same deprivation index) was followed up at 7-9 years of age, when 79% of cases and 87% of controls were successfully studied. Cases at 7-9 were significantly shorter (mean 126.0 cm, SD 5.6) than controls (mean 130.7 cm, SD 5.9); adjusted for parental heights a difference of 4.4 cm (95% CI 2.92 to 5.90 cm) remained. They had smaller head circumferences (mean 51.9 cm, SD 1.8) than controls (mean 52.8 cm, SD 1.7), were significantly lighter (medians 23.8 kg, IR 21.5 to 26.9 in cases, and 27.9 kg, IR 25.2 to 31.6 in controls) and had a lower body mass index (median 14.9, IR 14.1 to 16.0 in cases, and 16.3, IR 15.3 to 17.8 in controls). Despite these large growth differences, no statistically significant differences in cognitive outcomes were found. Mean IQ was 87.6 (SD 17.4) in cases and 90.6 (SD 17.1) in controls; after adjustment for organic cause and mother's IQ the mean difference was 1.7 IQ points (95% CI -5.2 to 1.9). There were no statistically significant differences in the reading, spelling, or reading comprehension scores; the mean standardised reading score was 93.5 (SD 16.2) for cases and 94.5 (SD 15.6) for controls. These results show that when carefully defined by velocity-based anthropometric criteria, nonorganic failure to thrive in infancy is followed by persisting stunting and wasting, and a reduced head circumference, but is not associated with cognitive or educational disadvantages at school age.

A mixture model for sucking patterns of breast-fed infants

Previous studies of sucking patterns have mainly been on bottle-fed babies and have assumed that the babies' sucks occur within bursts separated by gaps of predetermined minimum length which is fixed over the feed. This study considers babies that are breast-fed, a more complex and natural process than bottle-feeding, and develops a more sophisticated model for the pattern of bursts and gaps which allows the parameters of the process to vary over the feed. We consider data from four breast feeds of each of 32 babies. We develop a two-component mixture model based on an underlying Markov chain model for the switching between bursts and gaps. We use the model to provide summary statistics for each feed and give estimates of the normal range of each of the model's parameters.

Does a fall down a centile chart matter? The growth and developmental sequelae of mild failure to thrive

Fifty-two children aged 18 months who had fallen across two weight centile lines were compared to 52 controls. Five years after the initial study, 89% of these children were traced. At follow-up, four of the cases but none of the controls had been placed in care and cases were significantly shorter and lighter than controls. Reanalysis of the early weight data revealed that the screening criterion had been over-inclusive, identifying a majority with only borderline failure to thrive (FTT). Although the mean IQ was lower in the cases than in controls, the difference was not statistically significant. However, a significant association was found within the cases between severity of FTT and IQ. There was no difference in the number of behaviour problems reported. The use of a simple centile shift-based definition of FTT, while proving to be over-sensitive, has identified a subgroup of children who suffered adverse long-term cognitive outcomes.

Sex differences in weight in infancy and the British 1990 national growth standards

OBJECTIVES

To determine if there is a sex difference in infancy in the new British national standards for weight (based on data from 1990).

DESIGN

Weight data in a birth cohort were compared with the 1990 standards and Tanner and Whitehouse (1966) standards up to age 12 months.

SETTING

Newcastle upon Tyne.

SUBJECTS

3418 term infants.

RESULTS

Our cohort showed a mean difference in standard deviation scores of 0.42 between boys and girls (P < 0.0001) when compared with the 1990 standards. Two and a half times as many girls as boys had weights below the 3rd centile during the first year, with an equivalent excess of boys above the 97th centile (P < 0.0001). Similar results were found with Tanner and Whitehouse standards.

CONCLUSIONS

These differences could result in substantial sex bias in the identification of poor growth in early childhood. The standards need modification.

Thirst induced by a suckling episode during breast feeding and relation with plasma vasopressin, oxytocin and osmoregulation

OBJECTIVE

There have been anecdotal reports of increased maternal thirst during breast feeding, but the physiological mechanisms remain obscure. We have assessed and quantified the stimulation of maternal thirst during breast feeding (suckling), and correlated the changes with plasma oxytocin and vasopressin levels.

DESIGN

A within subject design was used with each subject acting as her own control. Each subject participated in a suckling period and a control non-suckling period the order of which was counterbalanced.

SUBJECTS

Ten healthy breastfeeding women ranging from 28 to 52 days post partum.

MEASUREMENTS

Thirst (assessed by a visual analogue scale), plasma vasopressin, plasma oxytocin (pOT), plasma osmolality and haematocrit, blood pressure, volume of milk transferred to baby, volume of water drunk immediately following each experimental period.

RESULTS

Thirst increased significantly more over a suckling period than over a comparable control period (P = 0.013). The peak level of thirst correlated with the volume of water consumed to satiety following the suckling period (r = 0.7, P = 0.024). As expected, pOT levels rose significantly in response to suckling (P < 0.001). Six women demonstrated a close relation between thirst and oxytocin response during the suckling period. Despite significant changes in thirst during suckling there was no increase in plasma vasopressin or in osmoregulatory parameters.

CONCLUSIONS

This study confirms that suckling is a potent stimulus to thirst in the mother, and is not associated with vasopressin release or dependent on any measurable alterations in osmoregulation. What actually stimulates thirst during breast feeding remains unknown, but there are two potential explanations for these observations: (1) suckling sends nerve impulses to the paraventricular and supraoptic nuclei in the hypothalamus which may have afferents within the central nervous system which stimulates a thirst response simultaneous with oxytocin release; (ii) a learned anticipation of thirst may be occurring in a situation associated with expectant fluid loss to preserve homeostasis.

Maternal behaviour and socio-economic influences on the bacterial content of infant weaning foods in rural northern Thailand

The bacterial contamination of infant weaning foods was examined in the context of a longitudinal study of lactation and infant growth, the Chiang Mai Lactation Study. Sixty-two mother-infant pairs were selected by random sampling from a rural area outside the city of Chiang Mai and studied for 48 hours in their homes on six occasions over the first year of life. Data on food hygiene practices and maternal factors were related to the total bacterial count per gram and coliform content of weaning foods. Bottle feeding, premastication, and mashing were significantly related to an increased bacterial content of weaning foods, while boiling foods to make soups, preparing in and feeding from a banana leaf, and using boiled water to prepare foods all reduced their bacterial content. Storage also increased the bacterial contamination in foods and foods were more highly contaminated in the rainy season. Maternal age and education were also related to some feeding practices. By promoting the feeding of traditional, but less contaminated weaning foods, an intervention is put forward which would aim to reduce weaning food contamination and thereby reduce incidence of diarrhoea in this area of Northern Thailand.

A move from hospital to community-based homes for people with learning disabilities: activities outside the home

Eighteen people with learning disabilities who moved from hospital to community-based homes were compared with a matched group of 18 who did not. A week-long time budget diary was used to record each occasion that the person left their home, the people accompanying them on each trip, their mode of transport and their destination. The diary was completed before they left the hospital and was repeated at least 1 year later. There was a strong correlation between the number of trips made from hospital wards at baseline and the number made at follow-up in both groups. Moving from the hospital had no significant effect on the number of trips made, but it did change their nature. Movers made more trips to unsegregated facilities; they made fewer trips alone and more in groups which included both staff and residents.

Modelling lactation using an inverse polynomial in a multilevel statistical model

A method is outlined for modelling the relationship between breast-milk production and time from delivery, suitable for data collected longitudinally. The relationship is described using inverse polynomials. In a two-level model the coefficients are specified as random variables across subjects, allowing within- and between-subject variation to be separately estimated. In a three-level model, day-to-day variation can also be separately estimated. The model is illustrated using data from the Chiang Mai Lactation Project. It allows the use of covariates that vary over time, and provides a method of analysis that is compatible with the practical constraints on the timing of data collection that are inherent in longitudinal studies.

Measuring outcome of total knee replacement using quality of life indices

A series of 26 patients was studied before and after total knee replacement to determine the change in their quality of life, expressed as a gain in Quality Adjusted Life Years (QALYs). Global health status was assessed using the Nottingham Health Profile, disability by the Harris scale, pain by the McGill Pain Questionnaire, and anxiety and depression by the Hospital Anxiety and Depression Scale. Substantial reductions were found in pain, anxiety and depression, and a significant improvement was found in mobility. These data were used to generate a 'QALY' (Quality Adjusted Life Year) comparable to the measure used by Williams (1) in his comparative evaluation of medical and surgical treatments. A gain of only 0.42 QALY was found for knee replacement, which is about one-tenth the figure given by Williams for hip replacement. The difference appears to be attributable not to differences in the success of the operations, but rather to the scope that QALY calculations give for allocating comparable patients to different quality of life states. Tighter criteria are needed if QALYs are to be used to guide resource allocation.

Weaning practices and breast-feeding duration in Northern Thailand

Current infant feeding guidelines recommend exclusive breast-feeding until the infant is about 4 months old to reduce the risks of early termination of breast-feeding, undernutrition and infection. In many societies, however, supplementary foods are given well before 4 months of age. The present paper describes weaning practices, factors associated with early supplementation and the effects of supplementation on duration of breast-feeding in a random sample of sixty northern Thai breast-fed infants studied prospectively from birth to 2 years of age. Composition of supplementary foods, energy and protein intake from supplements and changes in the supplementary diet with increasing infant age are also described. Rice-based foods were given from soon after birth; 81% of the sample had received supplements by 6 weeks of age. Early supplementary feeding was significantly associated with rural residence, large household size, maternal employment in agriculture and maternal age. Girls and infants with lower birth weights tended to be supplemented earlier. Despite early feeding of supplements, breast-feeding was prolonged, with median duration of 12 months. Early introduction of supplements and quantity of supplements consumed in the first 3 months were not associated with duration of breast-feeding. However, mothers who gave infant formula as the first supplementary food stopped breast-feeding slightly earlier, as did younger mothers living in households with more children.

Successful sustained lactation following postpartum tubal ligation

This study was undertaken to see whether tubal ligation performed within days postpartum, and associated with a delay in the initiation of breastfeeding, exerts a disruptive influence on successfully establishing lactation among the rural population of northern Thailand. Lactational performance of 12 rural northern Thai mothers was not affected by the delay in reunion of mothers with their babies as a result of postpartum tubal sterilization procedure when compared with a group of 8 other healthy mothers and babies. The volume of breast milk transferred, frequency of breastfeeding and the total feeding time spent on the breast were similar on days 15, 45, 90, 180 and 360 postpartum. This finding suggests that the pattern of intense breastfeeding activity as practiced by this group of mothers has a stronger influence on prolonged and successful lactation than early contact in the immediate postpartum period.

Relationships between nursing patterns, supplementary food intake and breast-milk intake in a rural Thai population

Relationships between nursing patterns, supplementary food intake and breast-milk intake were examined in a group of 52 Thai babies under 1 year of age. All data were collected over two consecutive days, 24 h/day. Total sucking time (min/day) and supplementary food intake (kcal/day) were significant predictors of breast-milk intake after allowing for the age of the baby: R-squared is 0.32 for sucking time and 0.39 for supplementary food intake. The two variables were themselves correlated (r is -0.47). The number of breastfeeds per day and their mean duration was determined for each case, counting each episode of attachment to the breast as a separate feed. Number and mean duration of breastfeeds were then evaluated as predictor variables. The duration of feeds had no predictive power. Number of feeds was linearly related to milk intake and combined with age was as good a predictor of milk intake as total sucking time (with R-squared 0.34). These results suggest that a simple count of breastfeeds is as valuable as more complex measures of sucking duration in predicting to breast-milk intake.

Predictors of breast milk intake in rural northern Thailand

A random sample of 52 mothers and infants from a rural area of Northern Thailand were studied in their homes for 48 h. Infants were breast fed on demand. Daytime feeds were test weighed with electronic averaging balances and nighttime intake estimated using a new method, Indirect Test Weighing. All feeds, both day and night, were timed to the nearest minute. Other variables measured by direct observation were infant weight, and supplementary food and water intake. Mean 24-h breast milk intake was 579 g (range 78-1,011 g) with a median between day coefficient of variation of 8.8%. The proportion of 24-h breast milk intake consumed at night ranged from 8 to 91%, and increased with increasing infant age. Significant positive associations were found between breast milk intake, and sucking time and infant weight. There were significant negative associations between breast milk intake and age, and supplementary food and water intake.

The bacterial content of infant weaning foods and water in rural northern Thailand

Samples of weaning food and supplementary water were collected for analysis of bacterial content from among a random sample of 65 infants under the age of 1 year living in a rural area of northern Thailand. Using geometric means, mean total bacterial count of infant's drinking water was 351 organisms/ml (95 per cent CIs 170-770), and the most probable number (MPN) of faecal coliforms/ml was 47 (95 per cent CIs 19-78). Mean total bacterial count of weaning foods was 38,000 (95 per cent CIs 25,000-59,000) organisms/g with 10 per cent recording counts greater than 1,000,000 organisms/g. Bacterial counts were similar to those reported in weaning food and water in other developing countries, and were above internationally recommended 'safe' levels. The bacterial count of water was not affected by boiling, due to poor cleaning and frequent re-use of utensils. Weaning foods were contaminated during preparation, in part through premastication and also via mode of cleaning of utensils.

Infant weight in relation to nutritional intake and morbidity in northern Thailand

A cross-sectional study of 58 infants (age range 2-53 weeks) was carried out in a rural area of northern Thailand. Total dietary intake (energy and protein from breastmilk and supplementary food) was measured directly during continuous observation over 48 h of randomly selected study subjects in their homes. Associations between infant weight and total energy intake, total protein intake and morbidity were analysed by multiple regression analysis. Up to 6 months of age, heavier infants had larger energy intakes, when age and birthweight were taken into account. In the 7-12 months age group, heavier infants consumed more protein and had fewer respiratory infections. Weaned infants older than 6 months were significantly heavier and consumed more protein than infants of similar age who were still receiving breastmilk. The lower protein intakes of the latter infants were due to the low protein concentration of breastmilk compared with supplementary food.

Serum prolactin and cortisol levels after suckling for varying periods of time and the effect of a nipple shield

Plasma prolactin and cortisol levels were measured in mothers breast feeding with or without the use of a thin latex nipple shield, and in mothers wearing a nipple shield but who were not nursing. Suckling duration and milk transfer were also recorded. Suckling duration ranged between 6 and 31 min, being significantly correlated with prolactin levels 40 to 120 min after the feed started. At the latter time, baseline prolactin level and time spent nursing accounted together for most of the variance in prolactin levels: R2 was 0.79 and 0.82 at 90 min and 120 min respectively. Prolactin was released as usual when the shield was in place: levels were not significantly different from levels without the shield. Suckling duration was also unaffected by the shield, but milk transfer was significantly reduced. Cortisol was not released by using the shield, and the shield alone (without suckling) did not release prolactin. The thin latex nipple shield has therefore no untoward effect on the release of these hormones during nursing.

Evaluating breast-milk intake by test weighing: a portable electronic balance suitable for community and field studies

A K-Tron Digital Scale (Model DS-1) was used to weigh a group of 52 new born babies. The regression of the weights on true weights obtained with a Sartorius electronic balance 3806MP was 0.9911, with an estimated residual variance of 5.25. With the same babies weighed on a Marsden Weighmaster, the estimated residual variance was 68.93. Data from published studies on other balances are presented for comparison. The K-Tron is a reliable, portable, battery operated balance suitable for measuring milk intake by test weighing in homes or in the field.

Individual patterns of milk intake during breast-feeding

The pattern of milk transfer during breast-feeding was ascertained for individual mother-infant pairs using a 'fractional' weighing technique. This method employs a single, fixed intermediate weighing on each breast, and a flexible, final weighing point at the 'natural' termination of feeding on each breast. The data demonstrate considerable variability between individuals both in feed length and in the rate of milk transfer from mother to baby. They show that the rate of intake tends to be consistent between the first and second breast, and that each mother-infant pair has a characteristic rate of milk transfer. Significant milk intake occurred from four minutes to the end of the feed on each breast. These results imply that breast-feeding 'rules' about the length of a feed can only be offered as helpful guidelines, rather than principles to be strictly followed. The results of a reciprocal nursing experiment suggest that the typical rate of milk transfer is a product of both milk release by the mother and milk demand by the baby.

Milk flow and sucking rates during breast-feeding

This study examined sucking patterns during breast-feeding in order to investigate the supposed 'nutritive' and 'non-nutritive' sucking dichotomy. The intervals between sucks were determined: they indicated that there is no bimodal distribution corresponding to 'nutritive' and 'non-nutritive' rates of sucking, but rather a complete gradation between the two. In a further experiment in which milk flow was assessed by test-weighing the baby at three-minute intervals during feeding, there was a linear relationship between milk flow and sucking rate: the higher the milk flow, the lower the sucking rate. These results were further substantiated by testing the sucking rate on an empty and full breast, and the sucking pattern of an infant with a non-lactating mother. The study shows that there is no dichotomy between two sucking rates, but rather a continuous variation in response to milk-flow rate.

The continuous measurement of milk intake at a feed in breast-fed babies

A method for the continuous measurement of milk intake during a breast-feed is described. A miniature Doppler ultrasound flow transducer, located in the tip of a latex nipple shield, is interposed between mother and baby during feeding. Preliminary results indicate the scope and current limitations of the method in terms of both populations and individual mother/infant pairs. An initial analysis of individual feeds indicates that two factors may contribute to the curtailment of intake during a feed from one breast: a progressive reduction in intake volume per suck, and/or an increase in the proportion of time spent pausing between bursts of sucking.

A quantitative analysis of the feeding behavior of suckling rabbits

Three experiments are reported on the feeding behavior of suckling rabbits ("kittens"). In the 1st the latency with which the kittens attached to the nipple, and then left the nipple, was determined. Attachment was very rapid and wholly reliable: on the 80 tests the nipple was seized in every case in under 9 sec, and on 67 of these in less than 3 sec. The kittens also invariably left the nipple within the next minute. If the kittens were 5 or 10 days old speed of attachment was unaffected by the presence or absence of saliva on the nipple, but 15- and 20-day-old kittens seized the sucked nipples more rapidly than the unsucked nipples. In a 2nd experiment with 12-day-old kittens, washing the nipple with solvents did not affect speed of attachment; nor did saliva. The results show that suckling rabbits, in contrast to rat pups, are not heavily dependent on saliva cues. In the 3rd experiment both attachment latency and milk intake were shown to be affected by an internal stimulus, a gastric load of.9% saline, 5 g/25 g body weight: attachment latency was significantly increased and milk intake reduced by 75%.

Effect of testosterone on neuronal refractory periods, sexual behaviour and luteinizing hormone: a comparison of time-courses

Measurements of the refractory period of stria terminalis neurones that are sensitive to testosterone propionate, of sexual behaviour and of plasma levels of LH were taken in castrated rats at various times after initiation of treatment with testosterone propionate. Levels of LH dropped within 24 h, before there was any change in neuronal refractory periods. The period of latency to mounting, however, was reduced to its shortest only after 7-8 days and ejaculations first occurred at the same time; these sexual responses correlated in time with reduction of the neuronal refractory period to its lowest level.

Does a change in the composition of human milk affect sucking patterns and milk intake?

Human breast milk of high and low fat content was fed to twenty-four babies aged 4-9 days from bottles. Changes in fat content parallel to those found during the course of a breast-feed (i.e., switching the baby from low-fat breast milk to high-fat breast milk) did not alter either milk intake rate or sucking patterns.

Effect of a traditional and of a new nipple shield on sucking patterns and milk flow

The effect of a traditional (Mexican Hat) and of a new (Thin Latex) nipple shield on the sucking patterns and milk intake of 5-8-day-old babies was examined. Milk intake was determined accurately by test weighing using a Sartorius electronic balance with animal weighing keyboard, and sucking patterns by filming the mouth of the baby. The Mexican Hat reduced milk transfer by 58% (P is less than 0.01), and increased sucking rate (P is less than 0.05) and time spent resting (P is less than 0.01). The Thin Latex nipple shield reduced milk intake by a smaller amount (22%), and had no significant effect on sucking patterns.

Testosterone-sensitive neurones respond to oestradiol but not to dihydrotestosterone

Testosterone is aromatized to oestradiol in the brain, and it has been suggested that its effects on the brain are produced by this metabolite. Oestradiol does indeed restore sexual behaviour in castrated rats, but is is much more effective if combined with a second metabolite, dihydrotestosterone. This may be because the two hormones have a synergistic effect on the brain; or because the central effect of oestradiol synergises with the peripheral effects of dihydrotestosterone (which include stimulation of penile development). Evidence that the corticomedial amygdala (CMA) and the preoptic area of the rat brain are both involved in the control of sexual behaviour led us to examine the neurones of the stria terminalis that connect the two. These neurones are hormone-sensitive; their absolute refractory period is lengthened by castration and reduced again by testosterone. So we have investigated the aromatization hypothesis further by examining the effect of oestradiol and dihydrotestosterone on these testosterone-sensitive neurones. Oestradiol has exactly the same effect as testosterone; dihydrotestosterone has no effect, whether it is given alone or in combination with oestradiol.

Sucking patterns of human babies on the breast

Twenty-seven 5--8-day-old babies were filmed during normal breast feeding (one feed each). Sucking patterns were determined from the film from a total sample of 17,676 sucks. Intersuck interals fell on two distributions: one of intervals between sucks during bursts of sucking (1.3 sec and less), and the other of rests between bursts of sucking (1.3 to greater than 12 sec). As the milk flow dropped towards the end of the feed on each breast, the sucking rate within bursts increased (P less than 0.05), but there were more (P less than 0.001) and longer (P less than 0.001) rests between bursts of sucking. This study provides normative data on a normal population for use in studies of breast feeding.