Down syndrome, trisomy 21 is the most common chromosomal disorder of moderate intellectual disabilities. The incidence is1in733.[1] One of the main characteristics of DS is short stature. Children with DS experience development retardation starts prenatally.[2] The Indian Academy of Pediatrics (IAP) created and suggested IAP 2015 Growth Charts for the observation of Indian children aged five to eighteen, and suggested WHO Growth Charts that were simplified for the observation of children younger than five years old. A combined WHO – IAP height and weight chart allows us to monitor growth from birth to 18 years on a single chart.Standard growth charts should not be used for children with DS because their growth and final height differ significantly from those of healthy children. A child with Down syndrome may exhibit extremely small stature if their growth is charted on a typical growth chart. Furthermore, any celiac disease or hypothyroidism that may be present could go unnoticed.[3] Racial differences undoubtedly play a significant role in growth, even though it is also influenced by biological and external variables.[4].Numerous syndrome specific growth charts have been developed.[5] Growth charts for DS that have previously been published are based on populations that are American, Arab, Sicilian, and Dutch.[6] Worldwide, the American DS growth charts are widely utilized. There are currently no growth charts available for DS children in India.The aim of the study was to conduct a comparative analysis of anthropometric parameters, such as weight, height and head circumference , in children less than 5 years with Down syndrome using two different growth chart approaches: the combined WHO-IAP chart and the U.S. Down Syndrome Specific Growth Charts. By examining the strengths and limitations of each approach, this study seeks to provide valuable insights into the most appropriate and accurate method for assessing growth and development in this population.

Aim 

To compare the anthropometric parameters of children less than 5 year with Down’s syndrome with combined WHO- IAP and Standard U.S Down syndrome specific growth charts. 

Objective of the Study 

To compare the anthropometric parameters (weight, height and head circumference) of children less than 5 years with Down’s syndrome in combined WHO- IAP and Standard U.S Down syndrome specific growth charts. 

Study Design

The study employed a comparative prospective study design.

Source of Data

The study population comprised of all confirmed cases of Down syndrome aged between 0-5 years, attending the outpatient department (OPD) or inpatient (IP) services at tertiary care hospitals, Out Reach area, from PHCs, Special Schools & Down syndrome club/associations in  Bangalore.

Inclusion Criteria

1. Cytogenetically confirmed cases of Down syndrome.

2. Individuals willing to provide consent and participate in the study and data collection.

Exclusion Criteria

Comorbid conditions like hypothyroidism, CHD etc. in a child with Down syndrome can affect its growth and hence need to be excluded.

Sample Size 

Hospital based time duration study.

The total number of 24 children whose age less than 5 year with karyotype confirmed Down’s syndrome were taken for this hospital based study during the study period (12 months after getting clearance from ethics committee).

Sampling Technique

Consecutive cases of children with Down syndrome meeting the eligibility criteria were included in the study until the required sample size was attained.

Study Variables

The study variables included weight, length (for children under 2 years or unable to stand) or height and head circumference.

Data Collection Tool

Data were collected using questionnaires and growth charts, specifically the combined World Health Organization (WHO)-Indian Academy of Paediatrics (IAP) chart and the U.S. Down Syndrome Specific Growth Charts.

Data Collection Procedure

Upon identifying a child with Down syndrome, data were collected after obtaining written informed consent from the parents or guardians. Information regarding existing medical problems, including congenital heart disease, hypothyroidism, other co-morbidities, and any previous surgeries, was obtained through the questionnaires.

Children underwent an anthropometric examination. For children under 5 years of age, head circumference was measured to the nearest 0.1 cm using a non-stretchable tape.

Weight was measured on an electronic digital scale to the nearest 0.1 kg. For older children, weight was measured while wearing minimal clothing, while infants and toddlers were weighed without clothing or diapers.

For infants and toddlers unable to stand unsupported, length was measured to the nearest 0.1 cm using an infant length board. For all other children, height was measured to the nearest 0.1 cm using a stadiometer.

Data Analysis

The collected data were entered into an Excel spreadsheet. Data analysis was performed using appropriate statistical software, R Software (Version 4.3.0).The normality of the data distribution was evaluated using Shapiro-Wilk-Test. Frequency distribution analysis were done for categorical data. Two sample independent T-Test and Mann Whitney-U-Test were used for continuous data. Pearson correlation analysis is used to estimate the linear relationship between continuous variables. P-Values were considered statistically significant at ≤=0.05.

The final sample available for analysis was 24 children less than 5 year old. After measuring anthropometric parameters by above mentioned standard procedure ,  descriptive statistics  and comparison of mean scores of anthropometric parameters in combined WHO-IAP and US Down syndrome specific growth charts and correlation analysis were performed.

Table 1: Comparison of Height Z-Score in Combined WHO-IAP & US Down Syndrome Growth Charts For less than < 5 Years.

In the present study, at 5% level of significance P-value is less than 0.05. Hence, we have sufficient evidence to conclude that there is significant mean difference of Height Z-Score in combined WHO-IAP & US Down syndrome specific growth charts for Age is less than 5 Years.

Figure 1: Comparison of Height Z-Score in Combined WHO-IAP & US Down Syndrome specific Growth charts  for Age < 5 Years.

Table 2: Comparison of Weight Z-Score in Combined WHO-IAP & US Down Syndrome Growth Charts for Age < 5 Years.      

In the present study, at 5% level of significance P-value is less than 0.05. Hence, we have sufficient evidence to conclude that there is significant mean difference of Weight Z-Score in IAP &US Down Syndrome Growth Chart for Age less than 5 Years. 

Figure 2: Comparison of Weight Z-Score in IAP &US Down Syndrome Growth Chart for Age (< 5 Years).

Table 3: Comparison of HC Z-Score in IAP &US Down Syndrome Growth Chart for Age (< 5 Years).

In the present study, at 5% level of significance P-value is less than 0.05. Hence, we have sufficient evidence to conclude that there is significant mean difference of HC Z-Score in IAP &US Down Syndrome Growth Chart for Age is less than 5 Years. 

Figure 3: Comparison of HC Z-Score in IAP &US Down Syndrome Growth Chart for Age (< 5 Years).

Table 4: Analysis of Parameter with Age Group.

Figure 4: In the present study there is an increase in trend observed in height (Z score) with age in US Down syndrome specific growth chart.

Figure 5: In the present study there is an increase in trend observed in weight (Z score) with age in US Down syndrome specific growth chart.

Down syndrome (DS) [7] is a chromosomal disorder with prevalence estimates to be 0.81/1000.[8] Children with DS have different growth patterns compared to children without DS.[9] Abnormal bone development is the most common feature and is hypothesized to be regulated by genetic factors.[10] 

Growth charts are invaluable tools in the assessment of childhood nutrition and growth. Indian academy of Pediatrics (IAP) prepared and suggested IAP 2015 Growth charts for monitoring growth in Indian children between the ages of 5 to 18 years and recommended simplified WHO growth charts for monitoring of children under the age of five years. A combined WHO – IAP height and weight chart allows us to monitor growth from birth to 18 years on a single chart and relation between child’s height and Mid parental height (MPH) can be readily observed on the same chart even for children younger than 5 years which is not possible on the split chart (separate charts for under 5 and older children).[11]

Height Z-Score in IAP & US Down Syndrome for age < 5 years

 Stunting is a chronic malnutrition, and the World Health Organization (WHO) [12] considers a child too small for his/her age when the height-for-age Z-score (HAZ) value is less than negative two standard deviations (i.e., <−2SD) from the median height of the WHO reference population. The mechanism for short stature in children with Down syndrome is multifactorial which include endocrine problems, nutritional deficiencies, cardiac comorbidities, auto immune conditions like type 1 diabetic mellitus, auto immune thyroiditis, celiac disease and others.

Down syndrome children have decreased growth noted since the time of birth as compared to normal children. In our study, we noted that height of children improved in their mean Z scores during first 5 years of life which was similar to the findings observed in the study by Cronk et al.  They noted that growth velocity, in terms of length and weight were maximally affected in first 2 years of life which showed improvement after 3 years of age.

In present study, the mean Z score for height in children < 5 years  as per WHO- IAP combined growth chart was -2.5891 SD, whereas  the mean Z score  was -0.6317 SD with the  US Down syndrome charts; which was statistically significant (P value = 0.0000022) . This means that, using combined WHO -IAP growth chart for assessment of height in children with Down syndrome would overestimate the prevalence of short stature in these children. 

Weight Z-Score in IAP & US Down Syndrome for age < 5 

Children affected by Down syndrome (DS) have a high prevalence of overweight and obesity compared to the healthy population. Moreover, they have an increased risk of metabolic derangements and cardiovascular complications in adulthood. The study reported as the combined prevalence of overweight and obesity differ between studies from 23% -70 %.[13]

We noted an increase in trend in weight Z scores with age in children less than 5 years.The findings was similar to Kaur et al where an initial period of wasting upto 6 months noted with Down’s syndrome.[14] Janet et al demonstrated that increased weight gain with age beyond 2 years and the weight stabilizes with age after an initial increase at 3 years of age.[15]

 In the present study; children less than 5 year, the mean Z score for weight as per combined WHO- IAP growth chart was  -2.2413 SD , whereas,  as per US Down syndrome growth chart mean Z score was -1.2431 SD; which was statistically significant (P value = 0.00088). This means that on using combined WHO -IAP growth chart, there would be overestimation of prevalence of underweight in Down syndrome children. 

Head Circumference Z-Score In WHO- IAP & US Down Syndrome Growth Chart For Age < 5 Years

The growth of head in children with Down syndrome is delayed compared to normal children. In the present study, in the children less than 5 year, the mean Z score for head circumference as per combined WHO-IAP growth chart was -2.4785, whereas per US Down syndrome growth chart it was  -0.2297; which was  statistically significant(0.0047). This means that using combined WHO -IAP growth chart overestimated the prevalence of microcephaly in Down syndrome children.

1. Down syndrome specific growth charts for US children have been used in our study as currently there are no validated down syndrome specific growth chart available for Indian children.

Growth in children with Down syndrome is further affected by comorbidities (i.e hypothyroidism, CHD) common in children with Down syndrome which we have excluded in the present study.

We observed significant values in Down syndrome patients with respect to weight, height and head circumference in children less than 5 year. In children  we noted an improvement in weight and height with age. Our results signify that Down syndrome children exhibit unique growth trajectories, differing significantly from normal children. Hence regular growth monitoring of Down syndrome children is of most important to timely identify any deviations as combined WHO and IAP standard growth charts, particularly in terms of lower height and weight, emphasizing the need for syndrome specific growth chart in clinical assessments. On comparison of anthropometric measures when plotted on combined WHO-IAP growth charts against  US Down syndrome growth charts, Combined WHO- IAP growth charts overestimated wasting, stunting and microcephaly. This signifies that the combined IAP- WHO growth charts are meant for growth assessment in normal children and hence cannot be used to assess growth in children with Down syndrome. As the  currently used US Down’s  syndrome specific growth charts take into account the growth parameters of US population, these charts are less than ideal for assessment of growth in Indian children with Down’s syndrome taking into consideration the genetic makeup, racial, ethnic and social factors. Hence there is a need for Down syndrome specific growth charts prepared for Indian children for more accurate growth monitoring of these children.

The authors declare that they have no conflict of interest

No funding sources

The study was approved by the “The Oxford medical college hospital & research Center, Bangalore. “

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