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*
Department of Nutrition, School of Medicine, University of Chile, Santiago, Chile and
Department of Pediatrics, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil
2To whom correspondence should be addressed at Department of Nutrition, School of Medicine, University of Chile, Independencia 1027, Santiago, Chile. E-mail: hamigo{at}machi.med.uchile.cl.
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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KEY WORDS: • growth deficit • risk factors • school children • Chile
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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, UNICEF 1999
).
In Chile, the epidemiological profile has been modified over a fairly
short period, yet even though infant mortality rates and malnutrition
(weight-for-age) have decreased, children are still not reaching their
full growth potential, especially children from families living in
poverty (Amigo et al. 1995
). Thus, the possibility
exists that the interrelationship among genes, environment and growth
has changed.
The government has declared this problem a priority and hopes to reduce
the level of growth deficit [lower than -1 SD of the
median of the NCHS/World Health Organization (WHO) standard]. The
target is to bring the deficit down from 33% (the baseline in 1987) to
20% among children entering primary school (Uauy and Garcia 1992
).
Identifying factors associated with mild stunting (lower than -1
SD) is relevant in countries such as Chile because this
degree of stunting is associated with lower academic performance in
school (Erazo et al. 1998
) and because the magnitude of
the problem is proportionally concentrated at this level of deficit
rather than at the moderate and severe stunting levels. Thus, it is
important to take mild levels of growth deficit into account when
formulating interventions for populations at risk, especially in
countries undergoing epidemiological transition.
Physical growth is related to genetic and environmental factors
(Mascie Taylor 1991
, Waterlow 1994
).
Previous studies in Chile have shown that the main factors associated
with stature deficit in the lower socioeconomic sectors of the
population are the parents’ short stature, low income and a history of
malnutrition (Amigo and Bustos 1995
).
It is important to conduct studies using children who are just
beginning school (6–8 y of age) because at this age growth deficit
reflects a reliable growth history of the child and offers an
appropriate moment to study risk factors. In addition, it is easier to
locate and measure the children in a country where almost 100% of
children attend primary school (UNICEF 1998
).
The aim of the present study was to identify and quantify the adverse environmental factors related to growth deficit in children whose parents are of short stature compared with those whose parents are not of short stature.
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SUBJECTS AND METHODS |
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TOPABSTRACTINTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Two thousand three hundred thirty-one children were evaluated in
their first and second years at school (6–8 y old). The selection was
made from children attending 12 state primary schools located in the
four poorest districts of Santiago. The socioeconomic status of these
districts was obtained from a score that determined social and
biological vulnerability (UNICEF 1994
). This score aimed
at establishing the vulnerability of the overall population of children
entering primary school by means of two factors: biomedical and
socioeconomic. The classification is used widely in Chile to guide
government programs and is based on 17 indicators such as the
proportion of the population living in poverty, the infant mortality
rate and maternal educational levels. Two groups of children were
selected, representing both low and normal stature. Children whose
height was between 1 and 3 SD below the median of the
height/age NCHS/WHO standard (WHO 1983
) were considered
to have low stature. This cutoff point was chosen based on the
assumption that the subjects represent a population for whom the
National Supplementary Feeding Program intervened nutritionally, along
with other social welfare interventions. Children of normal stature
were those in the ±0.5 SD range.
The stature of the parents was also measured. The group of low stature
children was subdivided into two groups according to their parents’
stature: Case 1 (n = 115) included children of whom
both parents had a stature of at least 2 SD below the
median of height/age of the reference at age 18. Case 2 (n
= 76) and the control group (n = 115) were
composed of children whose parents’ height was above -2
SD from the median. Figure 1
shows the study design.
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). Children from one-parent families, who had chronic conditions, who had been adopted or who were born in multiple births were excluded from the study.
Mothers were interviewed at home to gather information on socioeconomic and demographic conditions, maternal health during pregnancy and variables related to the child’s behavior and characteristics of the interaction between the child and his or her family. Factors related to anthropometric information of the newborn, the child’s health care, feeding patterns from birth to the sixth birthday and morbidity were obtained from clinical records (85% of the maternal and infant population is covered by the state health care service).
Descriptive statistics were analyzed first so as to identify any possible imbalance in the groups being compared. The variables were categorized according to different criteria for cutoff depending on their characteristics, such as lowest tercile for income, below -1 SD length for birth or adverse conditions (e.g., incomplete basic education). Control variables were assessed for effect modification and confounding using unconditional logistic regression. For this purpose, separate logistic models were carried out for type 1 and type 2 case children compared with the control group. Variable exclusion strategy considered a P-value of >0.5 in first stage of model building to be nonsignificant. Second, models with all pairwise interactions were built, using a P-value of 0.20 to declare statistical significance. For the final model, only interactions with P < 0.05 were considered. All statistical analyses were performed using SPSS 8.0, base, professional and advanced statistics modules.
This research was approved by the Ethic Committee of the School of Medicine, University of Chile, and all of the procedures that the committee recommended were followed.
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RESULTS |
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TOPABSTRACTINTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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). The height/age Z score of the children, as was expected, did not
differ between case 1 and 2 children (P > 0.05) but
did differ between these groups and the controls (P < 0.001). Maternal and paternal height was very low in case 1 children
and different from the height of the parents from case 2 and control
children. The per capita income was low in all three groups and was
significantly lower in case 1 children than in the control group.
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The final model that compared case 1 children (those with growth
deficit and parents with very short stature) with the control group was
significant, and the factors that entered into the model were short
length at birth [with an odds ratio
(OR)3
>4.8,
P < 0.001] and history of malnutrition (OR >5).
Drunkenness and a short period of exclusive breastfeeding were
significant, and unhygienic housing conditions tended to be significant
(P < 0.06) (Table 2
).
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).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Unhygienic housing conditions appeared to be an important risk factor in both groups of short stature, mainly in the children with parents not of very low stature. This variable was the standardized opinion of the interviewers in relation to the overall cleanliness of the home and could be a reflection of family concern not only for the house but as well for the children, also indicating the adverse conditions that children are exposed to in life.
The effect of a short period of breastfeeding on mild stunting (case 1
children) could reflect that in the groups with less income, an
adequate duration of the breastfeeding is an important factor in the
prevention of stunting. Numerous studies have shown that among children
from low socioeconomic levels, a short period of breastfeeding is
associated with a higher risk of complications and/or early primary
undernutrition; both factors determine growth retardation
(Tomkins 2000
, Villalpando and Lopez-Alarcón 2000
).
The prevalence of stunting is high in less-developed countries, and this situation can reflect the high frequency of undernutrition observed in such countries. In this study, the effect of a history of malnutrition suggests that its existence is still important in the determination of the stunting in countries undergoing fast epidemiological transition. Therefore, the surveillance of nutrition status and the preventive measures and treatment of malnutrition are undoubtedly important in these kinds of countries.
The apparent association between growth deficit and frequent
drunkenness in any member of the family may be due to an unfavorable
socioeconomic condition and/or that this risk factor triggers family
disruption and conflict (Christensen 1995
, Jacob et al. 2000
).
The lack of health insurance as a determinant of short stature might be another factor characteristic of low socioeconomic groups. It is doubtful that it directly affects growth. This is supported by the fact that the national health care system provides free health care for those living at the low socioeconomic level, and most children in our study were apparently healthy and free of severe chronic disease. In our opinion, this lack of health insurance is related to the social marginality, and for this reason, these groups are also those most exposed to adverse conditions.
The presence of short length at birth as a risk factor for short
stature at school age indicates that intrauterine growth is important
for a child’s subsequent growth (WHO 1995
). This
indicator has been suggested as a predictor of stunting at 3 y of
age in populations with high levels of stunting (Ruel et al. 1995
), and it has also been noted that children stunted at
birth in general do not catch up postnatally, indicating that this
deficit, if acquired by the time of birth, is irreversible (Ruel 2000
). It is important, therefore, that this measurement be
included in the common evaluation of newborn children.
According to the results of this study, to select beneficiaries for interventions aimed at preventing growth deficits, it is important to include quality-of-life indicators of the family and to not just consider biological factors.
The weakness of this research is that there was an overmatching in the socioeconomic factors, and for this reason it is possible that the social variables have not been fully expressed. On the other hand, the strength of this research is that identification of risk factors for stunting at the same level of poverty provides important information for identifying the at-risk population and/or selecting beneficiaries for social welfare programs, including those designed for nutritional intervention. Another strength of this study is its determination and quantification of risk factors, considering the cutoff point of -1 SD in a country where undernutrition has practically disappeared and the level of moderate and severe stunting is scarce.
In our opinion, to be able to decrease the prevalence of growth deficit in countries with epidemiological profiles similar to that of Chile, it is still important to reduce poverty and its consequences so as to reduce the adverse environmental factors that the children face and to formulate specific interventions for groups at risk from pregnancy on.
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FOOTNOTES |
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3 Abbreviations used: CI, confidence interval; OR, odds ratio.
Manuscript received July 16, 2000. Initial review completed October 20, 2000. Revision accepted November 2, 2000.
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REFERENCES |
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TOPABSTRACTINTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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1. Albala C., Vío F. Epidemiological transition in Latin America: The case of Chile. Public Health 1995;109:431-442[Medline]
2. Amigo H., Bustos P., Radrigán M. E., Ureta E. Nutritional status of school age children of differing socioeconomic levels. Rev. Med. Chil. 1995;123:1063-1070[Medline]
3. Amigo H., Bustos P. Factores de riesgo de talla baja en escolares chilenos de zonas rurales de alta vulnerabilidad social. Arch. Latinoam. Nutr. 1995;45:97-102[Medline]
4. Christensen E. Families in distress: The development of children growing up with alcohol and violence. Arctic Med. Res. 1995;54(Suppl 1):53-59
5. Erazo M., Amigo H., De Andraca I., Bustos P. Déficit de crecimiento y rendimiento escolar. Rev. Chil. Pediatr. 1998;69:94-98
6. Habitch J. P. Standardization of quantitative epidemiological methods in the field. Bol. Sanit. Panam. 1974;76:375-384
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8. Mascie-Taylor C. G. Biosocial influences on stature: A review. J. Biosoc. Sci. 1991;23:113-128[Medline]
9. Ruel M. T., Rivera J., Habicht J. P. Length screens better than weight in stunted populations. J. Nutr. 1995;125:1222-1228
10. Ruel M. T. The natural story of growth failure: Importance of intrauterine and postnatal periods 2000 Presented in the 47th Nestle Nutrition Workshop, Nutrition & Growth Santiago, Chile 2–6 April
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12. Uauy R., García F. Bases para un plan de acción en el área de nutrición materno-infantil 1990–2000. Rev. Chil. Nutr. 1992;20:136-152
13. UNICEF Una Propuesta de Clasificación de las Comunas del País Según Situación de la Infancia 1994 Andros Santiago, Chile.
14. UNICEF The State of the World’s Children 1998 Oxford University Press New York.
15.
Villalpando S., Lopez-Alarcón M. Growth faltering is prevented by breastfeeding in underprivileged infants from Mexico City. J. Nutr. 2000;130:546-552
16. Waterlow J. C. Causes and mechanisms of linear growth retardation (stunting). Eur. J. Clin. Nutr. 1994;48(Suppl 1):S1-S4
17. World Health Organization Measuring Change in Nutritional Status 1983 Guidelines for Assessing the Nutritional Impact on Supplementary Feeding Programmes for Vulnerable Groups. World Health Organization Geneva, Switzerland.
18. World Health Organization The newborn infant. Physical Status: The Use and Interpretation of Anthropometry 1995 WHO Technical Report Series 854, World Health Organization Geneva, Switzerland
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