Differential patterns of development: the interaction of birth weight, temperament, and maternal behavior.

A short-term longitudinal study of 83 families compared patterns of development between full-term small for gestational age (SGA) and normal birth weight (NBW) infants. Data were collected on infant temperament and maternal interaction at 3 and 6 months, and infant developmental outcomes at 6 months in order to investigate relationships between infant and maternal behavior, and developmental outcomes as a function of birth weight. Findings revealed few differences between SGA and NBW groups. However, the relations between infant temperament and maternal behavior varied as a function of birth weight and home environment. Specifically, more positive home environments were associated with higher ratings of maternal behavior and lower levels of infant negative reactivity for SGA but not for NBW infants. In addition, higher negative reactivity was related to lower performance on both the mental and psychomotor scales of the Bayley Scales of Infant Development (BSID), with stronger associations reported for SGA infants than for NBW infants.     

The relationship between intrauterine and postnatal growth on the subsequent psychomotor development of very low birthweight (VLBW) infants

ABSTRACT. The aim of this study was to demonstrate the relationship between intrauterine and postnatal growth and subsequent neurological and intellectual development of very low birth weight (VLBW) infants. The effect of intrauterine growth was assessed by comparing the developmental outcomes of the 131 appropriate weight for gestational age (AGA) infants with the 33 small for gestational age (SGA) infants. No significant differences were found between the two groups with respect to head circumference, neurological, intellectual or sensory handicap rates. The mean General Quotient (GQ) at the last clinic assessment for the AGA infants was 101.2 and 97.2 for the SGA infants. The effect of extra-uterine growth on subsequent development was assessed in the AGA and SGA infants separately, at the time of discharge and again at 12 months. The 31 AGA infants who failed to grow adequately in the nursery had more neonatal risk factors than the 100 AGA infants who continued to grow adequately after birth. This early postnatal growth failure was not predictive of developmental outcome. At 12 months of age, 26 infants (20%) who were initially appropriately grown at birth were failing to thrive. These infants had sustained more chronic diseases and caretaking disorders in the first year of life than their appropriately grown counterparts. They also had lower GQ and head circumference measurements (p<.05). The SGA infants who exhibited “catch up'’growth between birth and term had larger head circumference measurements at 1 year than those with persistent growth failure. Growth assessment at 12 months of age was not predictive of developmental outcome in SGA infants. We failed to show a relationship between intrauterine growth of VLBW infants and their subsequent development. AGA infants whose weights had dropped to the 3rd percentile by 12 months of age had a poorer outcome than their appropriately grown counterparts. Furthermore, early postnatal growth failure before term had no additional effects if catch up growth occurred thereafter. In the SGA group neither failure to reach the 3rd percentile by term or 12 months affected outcome.     

Growth of 519 Small for Gestational Age Infants during the First Two Years of Life

ABSTRACT. The physical growth of 519 small for gestational age infants (SGA), with a birth weight below the 10th percentile on our own growth curve, born in the region of University Central Hospital of Turku during the period June 1,1981-May 31, 1982, was studied. The study population consists of 4 517 term, appropriate for gestational age (AGA) infants, 488 term SGA infants, 320 preterm AGA infants and 31 preterm SGA infants. The degree of intrauterine growth retardation (IUGR) seemed to have an effect on physical growth in term SGA infants. Those term SGA infants with a low Ponderal Index (PI) (type II) were taller and had a larger head circumference at the age of 24 months than term SGA infants with adequate PI (type I). Among the preterm SGA infants the degree of IUGR seemed to have no effect on later growth. Smoking is still one of the main risk factors associated with poor intrauterine growth. In this study we also found that smoking has an effect on later growth; the children of smoking mothers were smaller than those of non-smoking mothers in the AGA group. Among the SGA infants the infants of non-smoking mothers were bigger than those of smoking mothers. This difference could be explained by other factors associated with SGA. We found that in spite of the catch-up growth during the first months, 26% of the severely SGA infants (birth weight below the 2.5th percentile) still had a weight below the 2.5th percentile at the age of 24 months.     

Effects of gestation and birth weight on the growth and development of very low birthweight small for gestational age infants: a matched group comparison

AIMS: To investigate the effects of small for gestational age (SGA) in very low birthweight (VLBW) infants on growth and development until the fifth year of life. METHODS: VLBW (< 1500 g) infants, selected from a prospective study, were classified as SGA (n = 115) on the basis of birth weight below the 10th percentile for gestational age and were compared with two groups of appropriate for gestational age (AGA) infants matched according to birth weight (AGA-BW; n = 115) or gestation at birth (AGA-GA; n = 115). Prenatal, perinatal, and postnatal risk factors were recorded, and duration and intensity of treatment were computed from daily assessments. Body weight, length, and head circumference were measured at birth, five and 20 months (corrected for prematurity), and at 56 months. General development was assessed at five and 20 months with the Griffiths scale of babies abilities, and cognitive development at 56 months with the Columbia mental maturity scales, a vocabulary (AWST) and language comprehension test (LSVTA). RESULTS: Significant group differences were found in complications (pregnancy, birth, and neonatal), parity, and multiple birth rate. The AGA-GA group showed most satisfactory growth up to 56 months, with both the AGA-BW and SGA groups lagging behind. The AGA-GA group also scored significantly more highly on all developmental and cognitive tests than the other groups. Developmental test results were similar for the SGA and AGA-BW groups at five and 20 months, but AGA-BW infants (lowest gestation) had lower scores on performance intelligence quotient and language comprehension at 56 months than the SGA group. When prenatal and neonatal complications, parity, and multiple birth were accounted for, group differences in growth remained, but differences in cognitive outcome disappeared after five months. CONCLUSIONS: Being underweight and with a short gestation (SGA and VLBW) leads to poor weight gain and head growth in infancy but does not result in poorer growth than in infants of the same birth weight but shorter gestation (AGA-BW) in the long term. SGA is related to early developmental delay and later language problems; however, neonatal complications may have a larger detrimental effect on long term cognitive development of VLBW infants than whether they are born SGA or AGA.     

Interaction and development in the first year. II. The effects of intrauterine growth retardation

Nine small-for-gestational age (SGA) and 10 appropriate-for-gestational age (AGA) fullterm infants were assessed using the Bayley MDI scale at 10 months, and infant-mother interactions observed at 6 months. Relationships among interaction parameters and development were compared with those of earlier interactions and development. At 6 months SGA and AGA mothers behaved similarly in interaction; SGA infants were more passive than AGA infants and demonstrated higher levels of state change. AGA infant vocalising frequencies at 2, 3 and 6 months were negatively related to MDI scores whereas maternal stimulation was positively related. Aspects of early SGA infant activity were negatively related to 10 month development; at 6 months several variables expressing dyadic interaction were negatively related. Ten month MDI scores were lower for the SGA than the AGA group. Socioeconomic status was related to MDI scores for AGA but not SGA infants. The results suggest that AGA and SGA infants behaved differently in interaction and that differential interaction patterns were linked with optimal development. Maternal stimulation and co-ordinated infant signalling in AGA dyads, and infant quietness and maternal activity encouraging quietness in SGA dyads, were patterns in high-scoring subjects. The exploratory nature of the study is noted.     

Mother-infant feeding interaction in full-term small-for-gestational-age infants

Maternal and infant behavior during feeding was assessed in 30 mother-infant dyads: 15 small-for-gestational-age (SGA) infants (birth weights below the 10th percentile) and 15 appropriate-for-gestational-age (AGA) infants (birth weights between the 25th and 90th percentiles). The groups were balanced for gestational age, sex, neonatal risk factors, and maternal age, parity, socioeconomic status, and race. Behaviors indicative of infant feeding difficulties were coded for mother and infant. The SGA mothers had higher frequencies of these behaviors than did their AGA counterparts. Qualitative ratings of interactive behavior were recorded for mother and infant: SGA infants had ratings indicative of less optimal interactions than those of the AGA group. Infant caloric intake (calories per kilogram per feeding) was calculated by first dividing the change in infant weight in grams before feeding and immediately after feeding by the infant's weight before feeding and then converting it to calories. Although no difference in caloric intake was observed between the two groups, infant behaviors and ratings were associated with caloric intake. These data suggest the importance of including neonatal behavior during feeding in the risk assessment of potential growth failure in SGA infants.     

Temperament in infants born prematurely

The temperament of infants born prematurely was studied to examine further the notion that prematurity may be a risk factor for an infant's subsequent social interaction. The Infant Temperament Questionnaire of Carey and McDevitt was revised and revalidated for an Australian population and sent to mothers of infants who had been born prematurely (36 weeks or less) and who were aged 4 to 8 months (corrected for prematurity). Two hundred and twenty-six questionnaires were distributed and 110 (49%) returned. There were no differences between respondents and nonrespondents with respect to gestational age, birth weight, method of delivery, Apgar scores, or perinatal complications. When compared to a control group (N = 240) of infants born at term and who came from families with similar demographic characteristics, infants born prematurely did not differ significantly on any of the nine temperament dimensions. Both groups had similar proportions of "easy," "difficult," and "slow to warm up" infants, and there were no significant differences in maternal global ratings of temperament between the two groups. Comparisons of infants of less than 33 weeks gestation gave results similar to those reported above. These data indicate that infants born prematurely have temperament profiles at 4 to 8 months similar to infants born at term.     

Prenatal cocaine and neuromotor outcome at four months: effect of duration of exposure.

The effect of prenatal cocaine exposure on the motor development of full-term infants was examined in a prospective study, controlling for maternal characteristics and exposure to other substances. Intrauterine cocaine exposure was determined at birth by maternal self-report and was verified by hair analysis. At 4 months, 120 cocaine-exposed (COC) and 186 non-cocaine-exposed (NON-COC) infants were assessed by blinded examiners using a standard evaluation of neuromotor function, the Movement Assessment of Infants (MAI). Relative to NON-COC infants, COC infants had significantly higher full-scale MAI total risk scores after adjusting for covariates (p = .05). Infants exposed through the third trimester of pregnancy (n = 48) had higher MAI scores for both total risk (p = .02) and Volitional Movement (p = .01), and when compared with infants exposed only within the first two trimesters (n = 72), they had significantly more deficits in Volitional Movement (p = .03). Although MAI scores for the majority of exposed infants were within the normal range, infants exposed through the third trimester were at significantly increased risk for motor dysfunction (relative risk = 1.6; 95% confidence interval = 1.1, 2.8). Intrauterine cocaine exposure had an adverse effect on infant motor development after the neonatal period; this association was related to the timing and duration of gestational exposure. Further study is needed to evaluate the long-term clinical implications of neuromotor abnormalities in prenatally exposed infants.     

Human placental IGF-I and IGF-II expression: correlating maternal and infant anthropometric variables and micronutrients at birth in the Pakistani population

Abstract Aim: To correlate infant birth weight with maternal and infant biometric data, including the expression of placental IGF-I and IGF-II at birth, and levels of serum zinc and ferritin. Methods: The data consisted of observations from 89 women from Karachi, Pakistan. Placental and cord blood samples were taken immediately following delivery and were subsequently divided into two groups, small and large for gestational age (SGA and LGA). Results: The mean birth weight was 2.79 kg; the prevalence of SGA being 13.4% (/=90th percentile). Placental IGF-I and IGF-II mRNA expression was greater in the LGA group (p < 0.05). Furthermore, a significant correlation was noted between infant birth weight and maternal anthropometric parameters (p < 0.01). Cord zinc levels were also significantly higher in the LGA group (p < 0.05). Conclusion: Maternal anthropometry, along with placental IGF-I and IGF-II mRNA levels, correlated significantly with infant birth weight suggesting the importance of these growth factors for birth weight outcomes. The higher zinc levels in the LGA group also suggest the importance of this micronutrient in foetal growth. Our results suggest that growth problems have a multifactorial aetiology arising from within the infant rather than due to maternal constraint alone.     

Temperament and increased weight gain in infants

The role of temperamental characteristics in accelerated and decelerated weight gain in normal infants has not been investigated previously except for differences in activity. The present study drew a random sample of 200 normal infants from a largely middle-class private practice. It found 24 infants who gained 30 or more percentile points in weight for length determinations between 6 and 12 months of age and 25 who lost 20 percentile points or more. These growth data were compared with contemporaneous findings on the Infant Temperament Questionnaire. Those gaining the most had significantly more difficult temperament ratings (p less than 0.05) and were perceived by their mothers as "more difficult than average" (p less than 0.001). Infants with the most decelerated growth were not temperamentally different from the general sample. Negative mood rather than low activity was the specific characteristic distinguishing the infants gaining the most (p = 0.006). Clinical experience would suggest that fussy infants are fed more to quiet them.     

Maternal trait anxiety, depression and life event stress in pregnancy: relationships with infant temperament

AIMS: To assess whether links exist between maternal trait anxiety (STAI), perceived life event (LE) stress and depression (Edinburgh scale) and infant temperament. STUDY DESIGN AND SUBJECTS: Women in the third trimester of pregnancy returned psychological self-report questionnaires; infant temperament was evaluated at 4 and 6 months by maternal and paternal report, while depression (concurrent Edinburgh scale) was also assessed at four and six months. As data were returned inconsistently at 4 and 6 months, we combined these two time points for simplicity of reporting and optimisation of numbers. RESULTS: Univariate logistic regressions on 970 subjects indicated that the pregnancy STAI (>40) scores were associated with 2.56- and 1.57-fold increases (maternal and paternal, respectively), in the odds of "difficult" infant temperament at 4 or 6 months. Concurrent Edinburgh scores (OR of 3.06 and 2.64 for maternal reports, respectively) were also predictive of infant temperament. Age, education, income, marital status, obstetric complications, infant gender and prematurity were not predictive of infant temperament. In stepwise multiple logistic regression analyses, the antenatal trait STAI (odds ratio 1.96) significantly predicted maternal reports of "difficult" temperament at 4 or 6 months independent of both antenatal and postnatal depression scores. There were similar trends for paternal reports of "difficult" temperament but these were not significant. Antenatal depression and perceived LE stress were not predictive of temperament. Finally, women (N=14) reporting domestic violence (DV) in pregnancy had highly significant increased Edinburgh and STAI scores. CONCLUSIONS: Maternal trait anxiety was predictive of "difficult" infant temperament, independent of "concurrent" depression and key sociodemographic and obstetric risk factors. These findings, while needing replication using objective measures of infant temperament, suggest that antenatal psychological interventions aimed at minimising anxiety may optimize infant temperament outcomes. There may be some benefit in shaping specific interventions to women reporting specific risk factors such as DV or past abuse.     

Growth in VLBW infants fed predominantly fortified maternal and donor human milk diets: a retrospective cohort study

ABSTRACT: BACKGROUND: To determine the effect of human milk, maternal and donor, on in-hospital growth of very low birthweight (VLBW) infants. We performed a prospective cohort study comparing in-hospital growth in VLBW infants by proportion of human milk diet, including subgroup analysis by maternal or donor milk type. Primary outcome was change in weight z-score from birth to hospital discharge. RESULTS: 171 infants with median gestational age 27 weeks (IQR 25.4, 28.9) and median birthweight 899 g (IQR 724, 1064) were included. 97% of infants received human milk, 51% received > 75% of all enteral intake as human milk. 16% of infants were small-for-gestational age (SGA, < 10th percentile) at birth, and 34% of infants were SGA at discharge. Infants fed >75% human milk had a greater negative change in weight z-score from birth to discharge compared to infants receiving < 75% (-0.6 vs, -0.4, p = 0.03). Protein and caloric supplementation beyond standard human milk fortifier was related to human milk intake (p = 0.04). Among infants receiving > 75% human milk, there was no significant difference in change in weight z-score by milk type (donor -0.84, maternal -0.56, mixed -0.45, p = 0.54). Infants receiving >75% donor milk had higher rates of SGA status at discharge than those fed maternal or mixed milk (56% vs. 35% (maternal), 21% (mixed), p = 0.08). CONCLUSIONS: VLBW infants can grow appropriately when fed predominantly fortified human milk. However, VLBW infants fed >75% human milk are at greater risk of poor growth than those fed less human milk. This risk may be highest in those fed predominantly donor human milk.     

The contribution of preterm birth and intrauterine growth restriction to childhood undernutrition in Tanzania

Objectives were to examine the growth patterns of preterm and growth‐restricted infants and to evaluate the associations of prematurity and intrauterine growth restriction (IUGR) with risk of stunting, wasting and underweight. Data from a cohort of HIV‐negative pregnant women–infant pairs were collected prospectively in Tanzania. Small for gestational age [SGA, birthweight (BW) <10th percentile] was used as proxy for IUGR. Anthropometry was measured monthly until 18 months. Length‐for‐age (LAZ), weight‐for‐length (WLZ), and weight‐for‐age (WAZ) z‐scores were calculated using the 2006 World Health Organization (WHO) Child Growth Standards. Stunting, wasting and underweight were defined as binary outcomes using a cut‐off of z‐scores. Multivariate Cox proportional hazard models were used to assess the associations between preterm and SGA to time to stunting, wasting and underweight. The study included 6664 singletons. Preterm and appropriate for gestational age (AGA) infants had slightly better nutritional status than term‐SGA infants and despite some catch‐up growth, preterm‐SGA infants had the poorest nutritional status. The gap in LAZ and WAZ z‐scores among the groups remained similar throughout the follow‐up. Compared with term‐AGA babies, relative risk (RR) of stunting among preterm‐AGA babies was 2.13 (95% confidence interval (CI) 1.93–2.36), RR among term‐SGA was 2.21 (95% CI 2.02–2.41) and the highest risk was among the babies who were both preterm and SGA (RR = 7.58, 95% CI 5.41–10.64). Similar magnitude of RR of underweight was observed among the three groups. Preterm and SGA infants should be closely monitored for growth failure. Intervention to reduce preterm and SGA birth may lower risk of undernutrition in resource‐limited settings.     

High-altitude ancestry protects against hypoxia-associated reductions in fetal growth

OBJECTIVE: The chronic hypoxia of high-altitude (>/=2500 m) residence has been shown to decrease birth weight in all populations studied to date. However, multigenerational high-altitude populations appear protected relative to newcomer groups. This study aimed to determine whether such protection exists independently of other factors known to influence fetal growth and whether admixed populations (ie, people having both high- and low-altitude ancestry) show an intermediate level of protection. DESIGN: 3551 medical records from consecutive deliveries to Andean, European or Mestizo (ie, admixed) women at low, intermediate or high altitudes in Bolivia were evaluated for maternal characteristics influencing fetal growth as measured by birth weight and the frequency of small for gestational age births (SGA or 相似文献   

Time-independent maternal and infant factors and time-dependent infant morbidities including HIV infection, contribute to infant growth faltering during the first 2 years of life

Studies investigating the predictors of growth in infants born to HIV-infected women in developing countries are limited. Using data from 886 Tanzanian HIV-infected women and their infants, we examined the impact of maternal socioeconomic and immunological status, infant characteristics at birth, and HIV, diarrhea and respiratory infections on infants' monthly length-for-age (LAZ) and length-for-weight (WLZ) z-scores during the first 2 years of life. We used restricted cubic splines to estimate average adjusted growth curves by categories of each predictor. LAZ decreased significantly during the first 2 years. WLZ increased from birth to 4 months but decreased significantly thereafter. Greater maternal schooling significantly reduced deterioration in LAZ and WLZ scores from birth to 24 months, while maternal CD4 cell counts >or=200 mm(-3) at baseline were associated with reduced deterioration in LAZ scores. Infants born pre-term or with low-birth weight were significantly more stunted and wasted than their reference groups at all time points though their rate of growth faltering was slower. Infant-HIV status was strongly associated with significantly greater deterioration in LAZ and WLZ scores, beginning at about 4 months of age. Episodes of diarrhea or respiratory infections were related to significantly lower WLZ but not LAZ scores, independent of infant-HIV status. In conclusion, maternal schooling, immunological status and infant infections are important predictors of early growth in children born to HIV-positive women.     

Influence of maternal birth weight on rate of fetal growth and duration of gestation

Birth certificates of infants born in Tennessee during 1979 to 1984 were linked with the birth certificates of their mothers, who were born in Tennessee during 1959 to 1966 (n = 43,891) to study the association between maternal and infant birth weights. A highly significant association (P less than 0.0001) between maternal and infant birth weights was found for both blacks and whites. Women who weighed 4000 to 4499 g at birth were at lowest risk for delivery of a small for gestational age (SGA) infant (5.9% for whites, 4.8% for blacks). The risk of giving birth to an SGA infant increased with decreasing maternal birth weight, reaching a maximum of 19.8% for white mothers who weighed 2000 to 2499 g at birth, and 20.0% for black mothers who weighed 1000 to 1499 g at birth. In contrast, the rate of preterm birth varied much less by maternal birth weight for both whites and blacks. These data suggest that maternal birth weight exerts a stronger influence on intrauterine growth than on the duration of gestation. Women who were smaller than average at birth should be considered at high risk for delivery of an SGA infant.     

Differential effects of intrauterine and postnatal brain growth failure in infants of very low birth weight

We investigated the contribution of brain growth failure to outcome in infants of very low birth weight (VLBW; less than 1.5 kg) who were appropriate for gestational age (AGA; n = 379) or small for gestational age (SGA; n = 102). Growth was assessed at birth, term, and 8 and 20 months' corrected age and results of a Bayley Mental Developmental Index (MDI) and neurologic examination were evaluated at 20 months of age. Both groups had similar 20-month MDI scores (93 vs 90) and similar rates of neurologic impairment (14% vs 10%). More SGA infants (25%) than AGA infants (14%) had a subnormal head circumference at 8 months' corrected age, indicating failure to catch up in head growth. Subnormal head size at 8 months predicted the 20-month MDI score for both groups. However, multivariate analysis indicated that, whereas subnormal 8-month head size was directly associated with the MDI score in AGA children, in SGA children 8-month head size was not significantly related to the MDI score when neonatal illness, neurologic impairment, socioeconomic status, and race were controlled for. We conclude that in AGA VLBW infants, subnormal head size at 8 months results from major neonatal illness and has adverse later effects. In SGA infants, subnormal head size at 8 months has many causes, including growth retardation in utero, which may not have an adverse effect on outcome; if subnormal head size is superimposed with neonatal illness, a poorer outcome is likely.     

Infant temperament,maternal feeding behaviours and the timing of solid food introduction

Despite guidance from the World Health Organization and the U.K. Department of Health, many mothers introduce solid food before their infant is 6 months old. The current study aimed to investigate relationships between maternal feeding behaviours (preintroduction and postintroduction to solids), infant temperament, and the timing of introduction to solid food. Eighty‐one women were recruited on low‐risk maternity units and were contacted at 1 week, 3, and 6 months postpartum. Mothers of infants (45 males, 36 females, mean birth weight 3.52 kg [SD 0.39]) completed the behaviours component of the Infant Feeding Style Questionnaire via telephone interview at 3 months. At 6 months, they were observed feeding their infant solid food at home and reported infant temperament using the Infant Behaviour Questionnaire‐Revised (short form). Partial correlations (covariates: birth weight, maternal age, breastfeeding duration, and postnatal depression) revealed negative associations between age of introduction to solid food and temperament (smiling and laughter) and laissez‐faire milk feeding behaviours; and positive associations between age of introduction to solid food and restrictive milk feeding behaviours and verbal involvement during an observed mealtime. Hierarchical multiple regression analysis revealed that an infant's birth weight and the degree to which their mothers perceive them to smile and laugh are key predictors of when they will be introduced to solid food, over and above other variables of interest (e.g., maternal milk feeding behaviours, breastfeeding duration, and postnatal depression).     

Proportionality Changes in the First Year of Life; the Influence of Weight for Gestational Age at Birth

ABSTRACT. Data on 55 small-for-gestational age (SGA), 56 average-for-gestational age (AGA) and 55 large-for-gestational age (LGA) infants whose growth had been monitored regularly from birth to 12 months are presented. SGA head-chest ratios were high at birth; but by 6 months they were very similar to AGA ratios, with values just below unity. Head-length ratios showed a steady decrement; SGA infants having the highest and LGA infants the lowest values at all ages. Chest-length ratios showed little change up to 6 months, with a steady decrease thereafter. Stem-stature ratios showed a similar pattern; and were confined within a narrow margin from 6 months onwards. These changes seem to be target orientated. We suggest the goal is that proportionality which enables the infant to attain the upright stature; and thus to sit, stand and walk at the appropriate time.     

Proportionality changes in the first year of life; the influence of weight for gestational age at birth

Data on 55 small-for-gestational age (SGA), 56 average-for-gestational age (AGA) and 55 large-for-gestational age (LGA) infants whose growth had been monitored regularly from birth to 12 months are presented. SGA head-chest ratios were high at birth; but by 6 months they were very similar to AGA ratios, with values just below unity. Head-length ratios showed a steady decrement; SGA infants having the highest and LGA infants the lowest values at all ages. Chest-length ratios showed little change up to 6 months, with a steady decrease thereafter. Stem-stature ratios showed a similar pattern; and were confined within a narrow margin from 6 months onwards. These changes seem to be target orientated. We suggest the goal is that proportionality which enables the infant to attain the upright stature; and thus to sit, stand and walk at the appropriate time.