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Screening
Prevalence and determinants of suspected developmental delays among 12-month-old children in northeast of Iran: a large-scale population-based study
  1. Seyedeh Vajiheh Kazemian1,
  2. Ehsan Mousa Farkhani2,
  3. Lida Jarahi1
  1. 1Department of Community Medicine, Mashhad University of Medical Sciences, Mashhad, Iran (the Islamic Republic of)
  2. 2Department of Epidemiology, Mashhad University of Medical Sciences, Mashhad, Iran (the Islamic Republic of)
  1. Correspondence to Lida Jarahi; JarahiL{at}mums.ac.ir

Abstract

Background Early identification of suspected developmental delays (SDDs) is crucial for planning early interventions. This study aimed to determine the prevalence of SDDs and the associated determinants in children aged 12 months in the northeast of Iran, using the Age and Stage Questionnaire-3 (ASQ-3) as the evaluative tool.

Methods This study conducted an analytical cross-sectional design to investigate all children who had completed the ASQ-3 screening form at 12 months of age within the time frame of 2016–2023 in the northeast of Iran. The necessary data were extracted from the electronic health record database associated with Mashhad University of Medical Sciences. To examine the factors associated with SDDs within each domain of the ASQ-3, a multiple logistic regression model was employed, and the results were presented using ORs along with 95% CIs.

Results Over 7 years, 236 476 children (96.74%) underwent routine ASQ-3 screening at 12 months. After excluding certain cases, 226 076 children (95.60%) were included. Among them, 51 593 children (22.82%) had a score below −1 SD, indicating SDD prevalence in at least one domain. The social–personal domain had the highest prevalence with 22 980 children (10.16%), while the gross motor domain had the lowest with 5650 children (2.50%). Logistic regression analysis identified strong predictors of SDDs, including hospitalisation at birth (OR=1.85, 95% CI:1.69 to 2.02), prematurity (OR=1.56, 95% CI: 1.37 to 1.79), urbanisation (OR=1.51, 95% CI: 1.45 to 1.57), boys (OR=1.36, 95% CI: 1.31 to 1.40) and lack of exclusive breast feeding until 6 months (OR=1.30, 95% CI: 1.25 to 1.34).

Conclusion The prevalence of SDDs highlights the urgency for prompt action, while considering contributing factors. Policymakers can address modifiable risk factors associated with SDDs, including urbanisation risks, support programmes for immigrant families and the importance of exclusive breast feeding until 6 months. Additionally, it is recommended establishing gender-specific local standard cut-off points for the ASQ.

  • epidemiology
  • health services research

Data availability statement

Data are available upon reasonable request. The data that support the findings of this study are available from Mashhad University of Medical Sciences but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission of Mashhad University of Medical Sciences.

http://creativecommons.org/licenses/by-nc/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi.org/10.1136/bmjpo-2023-002393

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    WHAT IS ALREADY KNOWN ON THIS TOPIC

    • The optimal early childhood significantly impacts their overall health and well-being.

    • It is crucial to estimate the number of children at risk of developmental delays to emphasise the necessity of interventions and policies targeting early childhood development.

    WHAT THIS STUDY ADDS

    • Around 23% of 12-month-old children in the northeast of Iran were found to have suspected developmental delays (SDDs).

    • Factors such as hospitalisation at birth, lack of exclusive breast feeding until 6 months and prematurity were identified as increasing the likelihood of SDDs in all areas of development.

    HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

    • The healthcare system will adjust its care programme for developmental screening in children, considering the mentioned contextual factors and giving priority to high-risk groups.

    Introduction

    Optimal early childhood development encompasses various domains including physical, social–emotional and linguistic–cognitive aspects.1 Failure to reach age-appropriate milestones in any of these areas is recognised as developmental delay.2 Timely identification of at-risk children holds paramount importance,3 as prompt referral to specialised interventions reduces the likelihood of long-term issues and improves outcomes in adulthood.4 5 Ensuring early access to interventions is a key priority in dealing with developmental delays.6 Estimating prevalence and understanding specific types of delays are essential initial steps in planning for early intervention.7 Moreover, to support improvements in the development of children, it is important to understand the factors that influence them. Based on the available literature, these factors can be classified into several main groups, including social, economic, political and cultural aspects, maternal and childhood factors, and factors related to pregnancy and childbirth.8 9

    The global prevalence of developmental delays is estimated at 5–15%. Nonetheless, without standardised assessment tools, over 30% of these children may not be identified, leading to potential delays in early intervention access.10 11

    The Age and Stage Questionnaire (ASQ)4 is a reliable screening tool recognised by the American Academy of Pediatrics for identifying at-risk children.7 12 The latest version, ASQ-3, is widely used due to its satisfactory validity and reliability.13

    In Iran, ASQ-3 has been integrated into primary healthcare for children.14 While several studies in Iran have used ASQ-3 to examine developmental delays,15 16 they had limitations such as small sample sizes and incomplete exploration of underlying factors associated with suspected developmental delays (SDDs). Thus, the present study aims to investigate the prevalence of SDDs and associated factors among 12-month-old children in Northeast Iran using ASQ-3.

    Methods

    Data collection and study population

    This analytical cross-sectional study was conducted in northeast of Iran, specifically in the population covered by Mashhad University of Medical Sciences (MUMS), within the time frame of 1 March 2016–30 February 2023. Data pertaining to the 12-month routine care of children were collected from primary healthcare centres. The confidentiality of individuals’ identities was strictly maintained throughout the process, using the electronic health record system affiliated with the Vice-Chancellor of Health of MUMS. To ensure individuals’ privacy and anonymity, the necessary data were anonymised and assigned a unique code. The inclusion criteria encompassed all children for whom ASQ-3 screening was documented during their 12-month routine care. The exclusion criteria comprised children who lacked scores in at least one domain of the ASQ-3 or had unavailable background information.

    Study parameters

    The data were divided into two distinct categories: child-related information and maternal-related information. Child-related information encompasses various aspects, including the scores achieved by children in each domain of the ASQ-3 at 12 months, gender, birth weight (<2500 g, ≥2500 g), gestational age at delivery (preterm if <37 weeks, term if ≥37 weeks), exclusive breastfeeding (EBF) status up to 6 months, multiple pregnancies, hospitalisation at birth and the outcomes of the screening tests conducted for phenylketonuria and hypothyroidism within the period of 3–5 days (normal, abnormal).

    The maternal-related information comprises several aspects, such as the place of residence (urban, rural), age at delivery (<18 years, 18–35 years, >35 years), education level (academic, non-academic education), nationality (Iranian, immigrant), occupation (housewife, student, employed), type of delivery (normal vaginal delivery, caesarean section (C/S)), child numbers (1 child, ≥2 children) and the relationship with the spouse.

    Study tools

    The ASQ-3 comprises 21 questionnaires tailored for age ranges from 1 to 66 months, with test–retest reliability ranges from 0.75 to 0.82, the internal consistency reliability ranges from 0.60 to 0.85 and the internal consistency ranges from 0.51 to 0.87.13 In the experiments conducted by the welfare and rehabilitation faculty during 2002–2007 in Iran, the validity, reliability and ability of the questionnaire to detect disorders were reported as 84%, 94% and 94%.17

    Each questionnaire of the ASQ-3 consists of a total of 30 items, which are categorised into five distinct domains namely communication, gross motor, fine motor, problem-solving and social–personal. Each item within the questionnaire is assigned a score of 10, 5 or 0, corresponding to the options ‘yes’, ‘sometimes’ and ‘not yet’, respectively. Paper questionnaires were provided to the child’s parents and after being completed, they were entered into the electronic health system by trained staff. The scoring range for each domain spans from 0 to 60. The interpretation of ASQ-3 scores relies on predefined cut-off points.

    Scores falling more than −1 SD are considered development on schedule, while children scoring between −1 SD and −2 SD require monitoring, and below −2 SD are at risk, necessitating referral. In line with national guidelines, this study used a single cut-off of −1 SD or below to categorise children as SDD14 (see table 1).

    View this table:
    Table 1

    ASQ-3 cut-off points for Iranian children at the age of 12 months

    Data processing

    Children with missing data were initially excluded from the study. Following this, data errors—those who obtained scores outside the 0–60 range in each domain—were also excluded. These data cleaning procedures and the application of inclusion and exclusion criteria led to a total of 226 076 children (110 808 girls and 115 268 boys) being included in the study. As a result, 6.98% of girls and 8.01% of boys were excluded from the dataset, as shown in figure 1.

    Figure 1
    Figure 1

    Enrolment of 12-month-old children for this study. ASQ-3, Age and Stage Questionnaire-3; MUMS, Mashhad University of Medical Sciences.

    Statistical analysis

    After inputting the data into IBM SPSS V.26, analysis was conducted. Descriptive statistics, such as frequencies and percentage frequencies, were visually represented through graphs and tables. The Χ2 test was used for statistical analysis at a significance level of 0.05. Additionally, the impact of factors associated with SDDs for 12-month-old children in each developmental domain was assessed using the multiple logistic regression model. The criterion for entry of contextual variables was determined based on a significance level of p<0.1 in the univariate logistic regression model. These results provided insights into the role of these factors in each developmental domain.

    Results

    From 2016 to 2023, 244 441 children received routine care at 12 months within the MUMS population. Of these, 236 476 children (96.74%) underwent ASQ-3 screening, and their results were recorded in the electronic health record system. After applying exclusion criteria, the study included a final sample of 226 076 children (95.60%). Within this final sample, there were 110 808 girls (49.02%) and 115 268 boys (50.98%). In terms of residential areas, 159 170 individuals (67.30%) lived in urban areas, while 66 906 individuals (32.70%) resided in rural areas. The developmental status of the studied population can be found in table 2.

    View this table:
    Table 2

    Population developmental status by ASQ domain, child gender and residency, 2016–2023*

    Out of 226 076 children, 174 483 (77.18%) demonstrated development on schedule (DOS) scores across all five developmental domains, while 51 593 children (22.82%) showed SDDs in at least one domain with a score −1 SD or below on the ASQ-3. The prevalence of SDDs was observed in 38 979 children (24.49%) in urban areas and 12 614 children (18.85%) in rural areas. In terms of gender, 27 896 boys (24.20%) and 23 697 girls (21.39%) displayed SDDs in at least one developmental domain.

    The prevalence of SDDs varied across the different developmental domains. Specifically, 22 980 children (10.16%) exhibited SDDs in the social–personal domain, 19 075 children (8.44%) in the problem-solving domain, 17 041 children (7.54%) in the fine motor domain, 16 300 children (7.21%) in the communication domain and 5650 children (2.50%) in the gross motor domain. The social–personal domain had the highest prevalence of SDDs, while the gross motor domain had the lowest prevalence. This pattern persisted when examining the data by gender and residential area.

    Boys showed more frequent SDDs in communication, problem-solving and social–personal domains, while girls had a higher prevalence in gross motor and fine motor domains. Additionally, a higher prevalence of SDDs was observed in urban areas compared with rural areas across all developmental domains.

    In regard to the number of domains with SDDs, 32 433 children (14.35%) exhibited SDD in a single domain. Moreover, 12 097 children (5.35%) displayed SDDs in two domains, 4643 children (2.05%) in three domains, 1610 children (0.71%) in four domains and 810 children (0.36%) in five domains. Figures 2 and 3 depict the developmental status of the studied population based on the number of domains with DOS results and SDD results.

    Figure 2
    Figure 2

    Developmental status in the studied population based on the number of DOS and SDD domains by gender, 2016–2023. DOS, development on schedule; SDD, suspected developmental delay.

    Figure 3
    Figure 3

    Developmental status in the studied population based on the number of DOS and SDD domains by residential area, 2016–2023. DOS, development on schedule; SDD, suspected developmental delay.

    To explore the factors associated with a heightened risk of SDDs, statistical analysis (Χ2 test) was conducted on underlying variables across each developmental domain. The results of these analyses are presented in online supplemental tables 1 and 2, which, respectively, provide an overview of the factors related to the child and the factors related to the mother.

    Supplemental material

    The role of factors related to SDDs in different domains of development was investigated using multiple logistic regression model after ensuring that relevant assumptions were met. The criterion for entering the underlying variables into the model was p<0.1 in univariate logistic regression. Table 3 shows the adjusted ORs for factors related to SDDs.

    View this table:
    Table 3

    Investigating the factors associated with SDDs by ASQ domain, using a multiple logistic regression model*

    After adjusting for other variables, the multiple logistic regression model revealed significant associations between specific factors and odds of having SDDs in the communication domain (p<0.05). The factors, in descending order of effect, included urbanisation, boys, multiple births, prematurity, hospitalisation at birth, immigrants, absence of EBF, C/S and mothers aged over 35 years at delivery.

    For the gross motor domain, the analysis showed significant factors associated with odds of having SDDs (p<0.05), in descending order of effect, included hospitalisation at birth, prematurity, multiple children, absence of EBF and C/S.

    In the fine motor domain, certain factors were significantly associated with odds of having SDDs (p<0.05), in descending order of effect, included hospitalisation at birth, immigrants, prematurity, non-academic education, urbanisation and absence of EBF. Additionally, the mother’s employment had a protective role.

    In the problem-solving domain, significant factors associated with odds of having SDDs (p<0.05) in descending order of their effects include hospitalisation at birth, absence of EBF, urbanisation, multiple births, prematurity, immigrants, boys and C/S.

    In the social–personal domain, significant factors associated with odds of having SDDs (p<0.05) in descending order of their effects include urbanisation, boys, multiple births, hospitalisation at birth, prematurity, absence of EBF, immigrants and C/S. Additionally, non-academic education was found to have a protective role.

    Discussion

    A total of 236 476 children, accounting for 96.74% of those who received routine care over a 12-month period, underwent screening using the ASQ-3. Among them, 226 076 children (95.60%) met the inclusion criteria and were included in the study.

    The reported prevalence of SDDs in this population was 22.82%. Studies using the ASQ instrument showed variations in prevalence attributed to differences in case definitions, selection criteria and cut-off points. For example, an Iranian study on children aged 2–60 months reported 14.70% and 26.40% prevalence using a cut-off point of less than −2 SD and −1 SD or below, respectively.15 A Norwegian study found a prevalence of 6.10% based on national cut-off points and 10.30% using US cut-off points for 12-month-old children.7

    The social–personal domain had the highest SDD prevalence within the population, while the gross motor domain had the lowest. A 2019 study in Iran echoed these results, with the social–personal domain showing the highest prevalence and the communication domain showing the lowest prevalence.16 Another study in Iran in 2014 reported the highest SDD prevalence in the fine motor domain and the lowest prevalence in the social–personal domain.18 In a study by Valla et al in Norway, the gross motor domain exhibited the highest prevalence of SDD in 12-month-old children.7 Discrepancies in SDD prevalence across domains in different studies may be due to variations in SDD definition, age differences, and genetic, ethnic and racial variations.

    The study found that boys had a heightened risk of SDDs in communication, social–personal and problem-solving domains, consistent with previous research.9 19 Proposed reasons for these differences include the higher levels of testosterone found in the umbilical cord of boys,20 the influence of epigenetic mechanisms resulting from gender-related disparities in the human brain21 and different parenting behaviours based on the child’s gender that affect the child’s development.22 Separate standard cut-off points for boys and girls in the ASQ are advised to mitigate potential false positive results.

    In this study, an association was found between prematurity and a heightened risk of SDDs across all developmental domains, consistent with previous research.23 24 Developmental delay is generally prevalent in preterm children,25 as indicated by Hochstedler et al, who found an inverse relationship between gestational age and developmental delays.26 This inverse relationship could be explained by the relatively less advanced stage of central nervous system development at birth.27

    Based on the current findings, the absence of EBF for the first 6 months was linked to an increased risk of SDDs across all developmental domains. Similar results were documented in a study by Drozd-Dąbrowska et al.28 Additionally, a study by Sacker et al revealed a 50% higher likelihood of delayed gross motor coordination in infants who were never breast fed.29 It is beneficial for healthcare professionals to educate mothers about the significance of EBF during prenatal and postnatal visits to support infant growth and development.

    In this study, children from multiple pregnancies showed an elevated risk of developmental delays in communication, problem-solving and social–personal development, echoing findings from other population-based studies.30 31 The reasons for this disparity remain unclear, whether it is due to lower birth weight and gestational age or inherent complexities of multiple pregnancies.

    The study also indicated a significant link between a history of birth hospitalisation and increased risk of SDDs across all developmental domains. Previous research has similarly demonstrated vulnerability to developmental delays in children with a history of hospitalisation, even in non-critical settings.23 32 33 Notably, the study highlighted a stronger association between hospitalisation at birth and SDD in the gross motor domain. Therefore, it is advisable to include this factor as an important criterion for early and periodical screening of developmental status in primary healthcare centres.

    The association of C/S with increased risk of SDDs in all domains, except fine motor, aligns with previous study findings,34 35 while other studies have not consistently established this link.23 36 The disparate outcomes among studies may be attributed to variations in reasons for performing C/S, potential for preterm birth and differences in gestational age at the time of delivery, accounting for divergent results.

    The results indicated urbanisation’s association with increased SDD risk in all domains except fine motor. Zablotsky et al illustrated rising developmental disabilities prevalence in urban areas over time,37 with justifications such as air and noise pollution, urban life stress and rural-to-urban migration outlined by Costa et al and Wang and Mesman.38 39 It is apparent that factors like chronic stress from migration and changes in family lifestyles in urban areas elevate vulnerability to physical and mental health issues.

    The current findings showed an increased risk of SDD in communication domain for children born to mothers over 35 years, consistent with Sanjaya et al’s research.35 Advanced maternal age’s impact on maternal and fetal health was highlighted in the study by Mehari et al.40

    Immigrant children from various nationalities had a higher likelihood of SDDs in all domains except fine motor. A study conducted in Singapore also found that minority ethnicity was associated with positive developmental screening outcomes in gross motor.10 Communication barriers and cultural differences were noted in Sapiets et al’s review as contributing to increased developmental delays in immigrant and minority groups.6

    Maternal education below the academic level was linked to a heightened SDD risk in fine motor, as observed in Agarwal et al’s study.10 This aligns with other research findings identifying lower maternal education levels as significant risk factors for developmental delays.19 23 This may be attributed to the increased awareness among mothers with higher education regarding various aspects of children’s growth and development, as well as their proactive approach in early detection and intervention for suspected disorders.

    The study’s strengths include a large sample size, a substantial timespan spanning multiple years, consideration of contextual factors and the utilisation of electronic health records for enhanced data accuracy and completeness. However, one of the limitations of the study was its cross-sectional design, which was due to the impossibility of population follow-up. Another limitation of the study was the lack of access to data on other factors affecting children’s development, including home environmental factors, diet at 12 months and father’s details for analysis.

    Conclusion

    In northeast of Iran, approximately 23% of 12-month-old children experienced SDDs. Factors such as hospitalisation at birth, lack of EBF until 6 months and prematurity increased the risk of SDDs across all developmental domains. Urbanisation, immigration, caesarean delivery, male sex and multiple births also significantly elevated the risk of SDDs in most developmental domains. These findings lay the groundwork for improved identification of children at risk of developmental delays. Based on these results, it is recommended that the healthcare system modify its care programme for developmental screening, considering the mentioned contextual factors and prioritising high-risk groups. Additionally, implementing an early, periodical and regular developmental screening programme for vulnerable children is strongly advised.

    Data availability statement

    Data are available upon reasonable request. The data that support the findings of this study are available from Mashhad University of Medical Sciences but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission of Mashhad University of Medical Sciences.

    Ethics statements

    Patient consent for publication

    Ethics approval

    This study was approved by the Biomedical Research Ethics Committee part of Mashhad University of Medical Sciences (approval number: IR.MUMS.MEDICAL.REC.1401.571). All the data used in this study were de-identified and provided by the electronic health record system affiliated with the Health Vice-Chancellor of Mashhad University of Medical Sciences. Therefore, identifiable individuals were not involved in the current study.

    Acknowledgments

    We would like to express our gratitude to the Vice-Chancellor of Research of Mashhad University of Medical Sciences and the Vice-Chancellor of Health of Mashhad University of Medical Sciences for their cooperation in this study.

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    Footnotes

    • Contributors SVK—conceptualisation, data curation, consulting analysis, investigation, methodology, project administration, software, validation, visualisation, writing (original draft) and writing (review and editing). EMF—conceptualisation, formal analysis, investigation, methodology, project administration, resources, supervision, validation, visualisation and writing (review and editing). LJ—onceptualisation, data curation, consulting analysis, funding acquisition, investigation, methodology, project administration, resources, software, supervision, validation, visualisation, writing (original draft) and writing (review and editing), and responsible for the overall content and guarantor.

    • Funding This work was supported by the Mashhad University of Medical Sciences (grant number 4011463).

    • Competing interests None declared.

    • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

    • Provenance and peer review Not commissioned; internally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.