Physical Growth Parameters - NCBI

Alexander K.C. Leung T. Oswald Siu Patrick C.W. Lai Stephen Gabos W. Lane M. Robson

Physical Growth Parameters of Chinese Children in Calgary SUMMARY

SOMMAIRE

Though ethnic variation in growth is well recognized, little is known about the physical growth of Chinese Canadian children. The objectives of this study were to establish the growth parameters for Chinese Canadian children and to compare them with those of Caucasian Canadians. The authors measured height, weight and head circumference during periodic physical examinations of children who attended their clnic between 1980 and 1984. These children were residents of Calgary, Alberta. Children with congenital anomalies or acquired chronic diseases were exduded. A total of 2,149 children (946 ethnic Chinese and 1,203 Caucasians) were studied. Differences in growth characteristics of Chinese Canadian and Caucasian Canadian children were established. The data suggest that the use of norual growth charts derived from growt data on the North American popultion may not be appropriate for Chinese Canadians. (Can Fam Physician 1987; 33:396-400.)

Quoique les variations ethniques des taux de croissance soient bien etablies, le developpement physique des enfants canadiens d'origine chinoise est peu connu. Cette enquete avait pour objectif d'etablir les parametres de croissance des enfants canadiens d'origine chinoise et de les comparer a ceux des Canadiens d'origine caucasienne. Les auteurs ont mesure la taille, le poids et le perimetre cephalique des enfants venant a leurs consultations, entre 1980 et 1984, au cours d'examens physiques periodiques. Ces enfants etaient residents de Calgary, en Alberta. Furent exclus les enfants souffrant d'anomalies congdnitales ou de maladies chroniques acquises. Un total de 2.149 enfants (946 d'origine chinoise et 1.203 d'origine caucasienne) furent suivis. Les auteurs purent etablir des differences entre les caracteristiques de la croissance des enfants d'origine chinoise et celles des Canadiens d'origine caucasienne. Les resultats suggerent que l'utilisation des courbes de croissance normale, etablies d'apres les mesures effectuees sur la population nord americaine nWest peut-etre pas appropride pour les enfants d'origine chinoise.

Key words: growth parameters, Chinese children, Calgary 1Dr.

Leung

is

a

clinical assistant

professor of Paediatrics in the University of Calgary. Dr. Siu is associate professor of Community Health in the University of Calgary. Dr. Lai is a member of the medical staff in the Department of Family Practice, Foothills Hospital, Calgary. Dr. Gabos is a medical computing specialist with the Alberta Cancer Board. Dr. Robson is a clinical assistant professor of Paediatrics in the University of Calgary. Reprint requests to: Dr. Alexander K.C. Leung, Alberta Children's Hospital, 1820 Richmond Road, S.W., Calgary, Alberta. T2T 5C7 396

PHYSICAL GROWTH in child- age of the British median value, dehood is an expression of a com- clined in children after they reached

plex interaction between the effects of' genetic and environmental factors. Little is known about the growth of Chinese children in Western countries. In earlier studies by Ling et al.2 young Chinese children proved to be shorter and lighter than Caucasians in the United States. Ashcroft et al., who made a study of the school children in Jamaica, demonstrated that Chinese children were shorter than Africans, Afro-Europeans and Europeans. More recently, a study done by Wheeler and Tan4 suggested that the height of Chinese children living in London, U.K., expressed as a percent-

two years of age. An important part of a comprehensive pediatric assessment is the evaluation of growth through the charting of body length, weight, and head circumference. The growth-chart references commonly used by Canadian physicians are based on data drawn from the North American population. The genetic background and feeding practices of ethnic Chinese children living in Canada are different from those of Caucasian Canadian children. The growth of these two groups of children may differ, and therefore the use of growth charts based on North AmeriCAN. FAM. PHYSICIAN Vol. 33: FEBRUARY 1987

tional Center for Health Statistics tended our clinic between 1980 and 1984 were obtained and followed dur(NCHS).5 ing subsequent periodic physical examinations. Most of these children were residents of Calgary. A total of 2,583 children were enrolled in the Metods The height, weight and head cir- study. One hundred and twenty-three cumference of all new patients who at- girls and 108 boys were excluded because they were neither Caucasians nor Chinese Canadians. Forty-five girls and 36 boys were excluded be*cause they had either congenital anoTable 1 Comparison of the Mean Head Circumference, Length and Weight at malies or acquired chronic diseases. A further 122 children were excluded beBirth of Chinese Canadians in Calgary with those of Caucasian cause an upper age limit at 10 years Canadians in Calgary and Caucasian Canadians in Hamilton was applied to maintain statistical staHead (cm) bility in the analysis. Of the remaining Sample Circumference Height (cm) Weight (kg) 2,149 children, there were 134 newSize (mean + s.e.) (mean + s.e.) (mean + s.e.) borns (17 Chinese boys, 22 Chinese girls, 44 Caucasian boys and 51 CauChinese casian girls) and 2,015 infants and Canadians in children (449 Chinese boys, 458 ChiCalgary nese girls, 582 Caucasian boys and 17 3.17 ± .35 34.1 ± 1.6 50.7 ± 2.3 Boys 526 Caucasian girls). ± 22 1.4 50.5 2.1 3.08 34.0 + .37 Girls + The height and weight measureCaucasian ments were made while the children Canadians in were not wearing shoes and shirts, Calgary though the older ones were wearing ± ± ± 44 51.8 3.36 2.8 .49 34.3 1.5 Boys underwear. The pre-school children 51.2 ± 2.5 3.23 ± .46 34.2 ± 1.0 51 Girls were weighed nude. Body lengths Caucasian were measured supine in children Canadians in under 18 months of age and standing Hamilton (6) in all other children. The head was 51.7 ± 2.6 3.50 ± .40 144 35.1 ± 1.0 Boys measured at its greatest circumference. 144 51.0 ± 1.9 34.3 ± 1.1 3.32 ± .45 Girls A single set of measurements was used for each child. All available birth measurements were used. For children with more than one set of measureFigure 1 ments in their health record, a comMean Male Head Circumference as a Function of Age puter program randomly selected one 52 l l l l l set per person for our investigation. The Statistical Package for the So50 cial Sciences (sPss) program was used to carry out most of the analysis in this 48 study.6 Statistical testing between curves was made based on the t-test o 46 between the parameters of the linear z regression models. Xg 44 f= _ can Standards for assessment of growth in Chinese Canadian children may not be valid. The objective of our study is to compare the physical growth parameters of Chinese Canadian children with that of Caucasian Canadians and with data from U.S. growth standards published by the Na-

Results The mean and standard error of various physical measurements at birth for the various groups of subjects studied were compared with those obtained by random sampling of all births occurring in Hamilton, Ontario, over an 18month period.7 (See Table 1.) There was no statistically significant dif-

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ference (5%) in the head circumference, length, and weight at birth between infant boys of Chinese and Caucasian extraction born in Calgary or Hamilton. Similarily, there was no 397

statistically significant difference (5%) in the head circumference, length, and weight measurements at birth between infant girls of Chinese or Caucasian extraction born in Calgary and Hamilton.

Figure 2 Mean Male Height as a Function of Age 140

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Figure 3 Mean Male Weight as a Function of Age 40 1 l I l 1 1 1 35 30 a

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Discussion

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one year of age (Figure 1). The difference did not achieve statistical significance. The mean height as a function of age of Chinese boys up to seven years was similar to that of Caucasian boys and the NCHS standard (Figure 2). By nine years of age, however, the mean height of Chinese boys was about 4 to 5 cm less than that of Caucasian boys -* and 4 cm less than that of the NCHS standard. This difference was statistically significant at the 5% level. There was no significant difference in the mean weight for Chinese boys, Caucasian boys and the NCHS values from birth to six years of age (Figure 3). By nine years of age, the mean weight of Chinese boys was 4.5 kg less than that for the Caucasian boys and about 2 kg less than the NCHS standard. This difference was statistically significant at the 5% level. Shortly after birth, the mean head circumference of Chinese girls started to fall behind that of Caucasian girls and the NCHS standard (Figure 4), resulting in an eventual difference of ap120 proximately 1 cm by two years of age. The difference did not achieve statistical significance. No significant difference in height was noted during infancy for Chinese girls as compared to Caucasian girls and the NCHS standard (Figure 5). Shortly after the age of two years the mean height of Chinese girls was consistently lower than that of Caucasian girls; the difference in height was about 3 cm at 10 years of age. The pattern of the increase in height as a function of age for Caucasian girls was . similar to that of the NCHS standard. No significant difference in weight was observed from birth to five years of age between Chinese girls and Caucasian girls (Figure 6). By nine years of age, however, the mean weight of Chinese girls was 5 kg lower than that of Caucasian girls. This difference was significant at the 5% level. We also observed that the mean weight of Caucasian girls between five and 10 years of age was higher than the NCHS standard.

Shortly after the newborn pe.riod, the mean head circumference c f the Chinese boys measured was no)tably smaller than those of Caucasian boys and the NCHS values resulting. Av difference of about 1 cm was apparebnt by

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Limited information exists on the 120 growth of Chinese children in Western countries. In 1983, Wheeler and Tan4 reported a non-randomized sample of 50 Chinese families in the greater London area; each family had at least one child under six years of age. Their reCAN. FAM. PHYSICIAN Vol. 33: FEBRUARY 1987

sults showed that Chinese children and teenagers living in the United Kingdom in 1981 were taller and heavier than indicated in growth standards published in Hong Kong in 1965,10 but below the U.K. median. Our study is based on a much larger number of

infants and children in a wider age range, and includes a control group of Caucasian Canadians. Since this was a retrospective study, potential bias was minimized. In this study, we found differences in the pattern of several growth para-

Figure 4 Mean Female Head Circumference as a Function of Age 1 l l 521 50

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Figure 5 Mean Female Height as a Function of Age

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meters between Chinese and Cauca-

sian Canadians in Calgary. At birth there were no significant differences in the head circumference, length, and weight between these groups. Our newborn measurements were similar to the size-at-birth standards for an urban Canadian population published in 1984.7 With increasing age, the head circumference of Chinese children became distinctly smaller in relation to that of Caucasian children. The height and weight of Chinese boys were similar to those of Caucasian boys throughout their first six to seven years of life. Appreciable differences in height and weight of Chinese girls as compared to their Caucasian counterparts were noted after two and five years of age respectively. The difference in mean head circumference of Chinese boys and girls compared to that of their Caucasian counterparts was noted soon after birth. By nine years of age, the differences in height, weight and head circumference between Chinese and Caucasian children are quite distinct. Our finding is similar to those of others who have observed that although Asian boys to age six have statures distributed over approximately the same range as those of Europeans, by age seven their range is distinctly shorter.8' 9 The marked difference in growth status at a later age may derive, at least in part, from the limits placed on their growth potential by their genetic background. The present study suggests that the growth of Chinese children differs from that of Caucasian children. It is well known that the rate of growth may vary throughout childhood, and that children of different ethnic backgrounds may vary in the time they take to complete their growth. Since our report is limited to children under 10 years of age, further study on persons over 10 years of age is needed to determine the full-grown height, weight and head circumference of Chinese Canadian children in Calgary. Clinical evaluation of growth depends on plotting the patient's height, weight and head circumference against standard growth charts. Since our study demonstrated significant differences in the growth parameters of Chinese children compared to those of Caucasians in Calgary and to NCHS standards, the usefulness of growth charts based on North American standards for Chinese Canadians is shown to be limited. Failure to recognize ra399

cial variations may lead to overdiagnosing of failure to thrive and of short stature in children of Chinese descent and thus to unnecessary investigations. One commonly used growth reference for Chinese children was published by Chang et al. .10, 11 who based their data on Chinese living in Hong Kong. Unfortunately, their data is now over 20 years old, and since environmental factors are significant to the growth of children,' the use of Chang's standards for Chinese living in Canada is limited.

Addendum

IS THIS THE

Since the submission of this paper, a new review of growth standards of Hong Kong children has been published.12

FACE OF A BOY WHO CAN'T SEE Acknowledgement ANYHING TO The authors are grateful to Lorraine LOOK FORWARD TO? Tiffin for expert secretarial assistance. RV Dat would it take to VVextinguish the spirit of an eight year old boy? Going blind could, but it didn't. If you look beneath Kevin's blindness, you'll find the spirit of a typical eight-year-old burning bright. Thanks to Kevin's exceptional courage and lots of support from the United Way. Kevin and thousands of others in our community are fighting to overcome misfortune, tragedy, or devastating disabilities through sheer force of will and determination. But they can't do it without the support of people like you who contribute to the United Way. Last year, the lives of one person in three were touched by the helping hands of United Way agencies and their 50,000 volunteers. Please, help us help.

Whereheree awill, thets heWay

This article is based on a paper presented at the 54th Annual Meeting of The Royal College of Physicians and Surgeons of Canada in Vancouver, B.C., September 10, 1985.

References 1. Rona RJ. Genetic and environmental factors in the control of growth in childhood. Br Med Bull 1981; 37:265 -72. 2. Ling S, King J, Leung V. Diet, growth and cultural food habits in Chinese-Ameri-

156 Front St.W., Toronto, Ont., M5J 1J3, Tel: (416) 979-2001 400

Phys Anthropol 1966; 24:35-44. 4. Wheeler E, Tan SP. Trends in the growth of ethnic Chinese children living in London. Annals Hum Biol 1983; 10:441-6. 5. Hamill PVV, Drizd TA, Johnson CL, Reed RB, Roche AF. NCHS growth curves for children birth- 18 years. Vital and Health Statistics Series II No. 165. DHEW pub no (PHS) 1978; 78 -1650. 6. Nie NH, Hull CH, Jenkins JG, Steinrenner K, Bert DH. Statistical package for the Social Sciences. 2nd ed. New York: McGraw Hill, 1975. 7. Blidner IN, McClemont S, Anderson G, Sinclair JC. Size-at-birth standards for an urban Canadian population. Can Med Assoc J 1984; 130:133-40. 8. Eveleth PB, Tanner JM. Worldwide variation in human growth. Cambridge: Cambridge University Press, 1976. 9. Marshall WA. Geographical and ethnic variation in human growth. Br Med Bull 1981; 37:273-9. 10. Chang KSF, Lee MMC and Low WD. Standards of heights and weights of Southern Chinese Children. Far East Med J 1965; 1:101-9. 11. Chang KSF, Lee MMC, Low WD, Kvan E. Height and weight of Southern Chinese Children. Am J Phys Anthropol 1963; 24:497 -509. 12. Fung KP, Lau SP, Chow OKW, et al. A survey of growth of Hong Kong children Hong Kong J Pediatr 1985; 2:105-16.

Figure 6 Mean Female Weight as a Function of Age 40 35 30__

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can infants. Am J Chinese Med 1975; 3:125-32. 3. Ashcroft MT, Heneage P, Lovell HG. Heights and weights of Jamaican school children of various ethnic groups. Am J

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CAN. FAM. PHYSICIAN Vol. 33: FEBRUARY 1987