Lu-Yu Xie ·Folefac D.Atem ·Sari Bar ·Matthew Sunil Mathew ·Cynthia Lebron ·Catherina Chang ·Ruby Natale ·Sarah E.Messiah

Abstract Background Preschool-age children with developmental disabilities (DD) have higher prevalence of obesity than children without DD.This study aimed to explore the relationship between parent perception of their children’s anthropometric phenotype and child body mass index (BMI) z score change over one school year among preschoolers with DD.Methods The analysis consisted of a subsample (N = 64) of children with DD from a larger randomized controlled trial to test an obesity prevention program in the childcare center setting.Parents ranks their child’s anthropometric phenotype on a visual silhouette chart on a scale from 1 (underweight) to 7 (obese) and that rank score is compared to their BMI z score change over one school year.Results The majority (75%) of parents with an obese child underestimated their child’s anthropometric phenotype while 7%parents with a non-obese child overestimated.Parent overestimation of child anthropometric phenotype status is associated with increased BMI z score change over 1 school year among preschool-age children with disabilities.Conclusion Parental overestimation of child anthropometric phenotype status was associated with weight gain in preschool children with DD after one school year.

Keywords Anthropometric phenotype Children·Developmental disabilities·Obesity·Weight perception

Introduction

Childhood obesity is now a global public health crisis[1].In 2019,about 40 million children under the age of 5 were overweight [(85th percentile ＜ body mass index(BMI ＜ 95th percentile adjusted for age and sex)]or obese(BMI ＞ 95th percentile adjusted for age and sex) worldwide[1].In the United States,13.9% of preschool-age children are obese [2].In developing countries,the prevalence of obesity in preschool children varies from 14.4% in Uzebekistan to 0.5% in Nepal [3].

Compared with typically developing children,obesity is even more prevalent (20%) in children with developmental disabilities (DD) [4,5].DD is defined as a group of chronic conditions that develop in childhood that may or often cause a variety of functional limitations in daily life [6].Examples of DD in children include intellectual disability,physical disabilities,attention-deficit/hyperactivity disorder (ADHD),autism spectrum disorder (ASD),cerebral palsy,learning disabilities [6].

Specifically,a meta-analysis including 42 studies and about 50,000 patients with ADHD demonstrated the obese rate in children with ADHD was 1.2 times higher than children without DD[7].Similarly,a large national study,including more than 85,000 participants found children with ASD were 42% more likely to be obese compared with healthy children [8].Another study from Australia estimated the obesity prevalence among young children with ID was 8.5%,significantly higher than the obese rate of 5.4% in children without intellectual disability (ID) [9].

Previous studies have demonstrated that parents do not accurately identify their child’s anthropometric phenotype (represents BMI in general,or the ratio of weight to height) [10,11].Although inaccurate estimation of preschool children’s weight is currently a major public health concern in preventing childhood obesity [12],few studies have examined the impact of parent perception of their child’s anthropometric phenotype on longitudinal BMI change among preschool-age children with DD.Therefore,the objective of this study is to explore the relationship between parent perception of their preschool child’s anthropometric phenotype and child BMIzscore change over one school year among preschoolers with DD.We hypothesized that the majority of parents with an unhealthy weight preschooler would classify their child as healthy or normal weight.

Methods

Study design and participants

This study is a sub-analysis from a randomized controlled trial(RCT) (Clinical Trial #NCT01722032),that tested the effi-cacy of“Healthy Caregiver-Healthy Children (HC2)”[13],an obesity prevention program on the adoption of quality nutrition and increased physical activity patterns among preschool children.This RCT enrolled a total of 1105 children 2-5-years old from 24 childcare centers (CCCs) in Miami-Dade County,Florida in the 2015-2016 school year.Twelve CCCs were randomized to the experimental group,which received on-site intervention related to a nutrition-based curriculum,and 12 CCCs were randomized to the control group and received an attention control safety program.

This sub-sample analysis included 64 children with a DD including ASD,learning disability,physical disability,speech/language impairment,intellectual/cognitive disability and other disabilities.Disabilities were identified through parent self-report.

Measures

Visual perception of child anthropometric phenotype

Caregivers were asked to rate their child’s anthropometric phenotype on a visual silhouette chart on a scale from 1(underweight) to 7 (obese) [14].If parents rated their children’s phenotype anywhere in the range of 1-5,they were categorized to the“perceived non-obese”group.If parents selected 6 or 7 on the visual silhouette chart,they were categorized to the“perceived obese”group.

Child body mass index

Children’s height and weight were measured by stadiometer and a digital scale,respectively,then converted to BMI percentile and BMIzscore adjusted for age and gender via growth charts provided by the Center for Disease Control and Prevention (CDC) [15].BMI ≥ 95th percentile was classified as obese [2].

Covariates

Child age,gender,race/ethnicity,parents’ education level,preferred language and HC2 intervention arm were included as covariates.

Statistical analysis

The association between weight change (BMIzscore) of preschool children with DD after a school year and parents’misperception on child weight status was explored via linear regression analysis controlling for baseline BMIzscore and other covariates listed above.All statistical analyses were performed in SAS v 9.4 (SAS Institute Inc,Cary,NC,USA).

Results

The analytical sample was predominately male (53.1%),aged 3-5 years (53.1%),Hispanic (63.9%) and spoke English as the preferred language (66.7%) (Table 1).73.4% of the sample were randomized to the HC2 treatment arm over the school year and 16.4% were obese.

Most parents with a healthy weight child (BMI ＜ 95th percentile) accurately categorize their child’s BMI status (93%),while about 7% parents overestimated their child’s anthropometric phenotype.Conversely,75% of parents with an obese child (BMI ≥ 95th percentile) underestimated their child’s anthropometric phenotype,whereas only 25% of parents with an obese child perceived their child’s phenotype correctly.

After controlling for baseline BMIzscore and other demographic factors (child age,gender,race/ethnicity,parents’ education level,preferred language,and HC2 intervention arm),the children of parents who overestimated theirchild’s anthropometric phenotype significantly increased their BMIzscore over the school year (β=1.55,P=0.03).In other words,parental overestimation of child anthropometric phenotype status was significantly associated with more BMIzscore gain,while a parental underestimation of child anthropometric phenotype was not a significant predictor (β=-1.02,P=0.30).Baseline BMIzscore was one of the most significant predictors for child BMI score gain.Specifically,mean BMIzscore at the end of the school year significantly increased by 0.51 units for each unit increase of the BMIzscore at baseline,after controlling for other predictors (β=0.51,P=0.003).

Table 1 Baseline characteristics of participants (N =64)

Discussion

Results from this analysis showed that the majority of parents of a healthy-weight preschool-age child with DD accurately categorize their child’s anthropometric phenotype.However,most parents with an obese child fail to accurately identify their anthropometric phenotype.Importantly,our results show that parental overestimation of child anthropometric status is significantly associated with more BMIzscore gain instead of being a potential protective factor.Conversely,our results show that underestimation of child anthropometric phenotype status is not associated with less BMIzscore gain among young children with DD.Our findings have implications for healthy weight development efforts among young children with DD in the USA.

Our findings are consistent with those reported from previous studies among children without DD.Robins and colleagues reported on the relationship between parental perceptions of child weight status and weight gain among 4-13-year olds [16].Similarly,they found children gained more weight if parents exaggerated their child’s weight status.As such,Kroke et al.[17]suggested that maternal perceptions of child weight status should be considered while addressing childhood obesity due to the evidence that it is a significant contributing factor to healthy weight development in childhood.

To date,the evidence base is not adequate to help explain why parental overestimation on child weight may be associated with more weight gain,and especially among parents of a preschool-age child with a DD.One interesting hypothesis is that being labelled as“fat”can harm the self-regulation of body weight,and then in turn may cause more weight gain[18].Parents may overfeed their (perceived) obese children because they may think“bigger”children need more food to be satisfied compared to normal-weight children [19].As a consequence,this may result in permanent patterns of overeating behaviors in young children.Specifically,for young children with both DD and obesity,parents may treat the weight issue as a lesser priority compared to a child with DD alone.Additionally,obesity may become a reason not to participate in various forms of physical activity.

The prevalence of obesity in preschool-age children has more than doubled over the last three decades [20].Several disease-specific and non-specific factors may contribute to the higher obesity rate among children with DD.For example,children with DD are more likely to suffer from physical limitations,which may increase the likelihood of being obese.In addition,they may be prescribed with some psychotropic mediations (such as,atypical antipsychotics,some anticonvulsants,etc.) for behavioral control.Unfortunately,the metabolic side effects associated with drug treatment can also cause undesired weight gain among those children with DD.Moreover,family factors,including how parents perceive their child’s weight status,also play important roles in combating childhood obesity.Parental misperceptions on child weight phenotype are considered as potential risk factors for unhealthy weight gain among children with DD [16,17].

Indeed,parental misperception of their child anthropometric phenotype is a common and global phenomenon:up to 75% of parents in the United States misclassified their child’s weight status [21].To address this issue,national measurement programs have been initiated in UK and USA to assist parents to correctly identify their child’s weight [12,22].Hence,educating parents on healthy child weight status and raising the awareness of childhood obesity at an early age may help decrease the high obesity rate among young children with DD.

Several limitations of this study should be mentioned.First,information regarding children’s DD diagnosis was reported by caregivers,which might be prone to recall and report bias.Second,although some DD may be attributed to genetic predispositions or related to genetic conditions,DD may occur or be diagnosed at any time in childhood secondary to injury,infection,environmental triggers or other unknown factors [6].Our sample only included preschoolage children;some children at this age may have not been affected or may not have received a diagnosis of DD to date.Therefore,the results of our study may be generalized to preschool age children with more overt DD,and may not be generalized to all preschool age children without DD.Third,this sub-analysis includes a relatively small sample size but provides one of the first studies of its kind in the literature.Lastly,in addition to parental influence,other factors such as unhealthy eating habits,types of affected disability,and sedentary lifestyles could also contribute to excessive weight gain in childhood.In the future,longitudinal studies rigorously controlling for those factors are needed to further examine the association between parental perception and childhood weight status.

In conclusion,contrary to popular belief,our study showed a parental overestimation of child anthropometric phenotype status was not associated with BMIzscore decrease;rather,it was found to be associated with BMIzscore gain in preschool children with DD after one school year.This indicates that it is critical to educate parents on accurate anthropometric phenotype categories to improve the awareness of healthy child weight development.Clinical practitioners can help parents at high risk of misperception to correctly evaluate their child’s weight status.Early intervention by both parents and practitioners could be critical in the prevention of obesity,as dietary patterns and eating habits are often formed early in childhood.In the future,larger studies could focus on understanding how this counterintuitive phenomenon contributes to the development of healthy body mass index growth trajectories.

Author contributionsRN and SEM were the multiple principal investigators of this project and thus had oversight of all aspects of the study.For this manuscript,LX was responsible for conceptualization,data curation,formal analysis and completing the original draft.FA oversaw all statistical analysis.SB and CL assisted with resources and writing review and editing.CC assisted with project management and writing review and editing.SEM was responsible for senior oversight for all phases of the project and the final approval of the version to be published.All authors approved the final manuscript.

FundingThis work was funded by the United States Department of Agriculture (Grant number 2014-08403) and NIH F31 (Grant number NIDDK F31DK116533).

Data availabilityThe data that support the findings of this study are available on request from the corresponding author.The data are not publicly available due to privacy or ethical restrictions.

Compliance with ethical standards

Ethical approvalThis project was reviewed and approved by the University of Miami Institutional Review Board.

Conflict of interestNo conflicts of interest to report for all authors.No competing financial interests exist.

Patient consent statementInformed consent was obtained from all participants or guardians.