D-score as a universal measure of child development

For decades, Dutch baby clinics have been measuring young children's development using 75 characteristics, the 'Van Wiechen schema'. The characteristics are milestones such as ‘Can the child stack two blocks?’, ‘Can the child walk?’, and ‘Does the child use two-word "sentences"?’.

At each age, the baby clinic measures a handful of characteristics, matched in difficulty to the child's age. Wouldn't it be useful and valuable to develop a measurement that captures a child's development across all ages in one metric? TNO developed a measurement scale, the D-score, which indicates a child's development.

In the Netherlands, the D-Score complements traditional practice in which different developmental milestones are evaluated separately or domain-specific scores are used, but it can be introduced in countries where only height and weight are measured using any developmental measurement instrument.

Development potential

The D-Score can be used to show which children are realising their potential. Is a child developing within the limits and progressing over time? This means a child cannot only be followed over time, but it is also possible to compare children with each other and see how a child develops compared to a reference group. This can tell us whether a child is lagging behind in its development. But above all, the D-Score is a positive measure; it indicates the extent to which children are reaching their potential.

Practical implementation

In collaboration with the UMCG, Allegro Sultum, and Youth Health Care Centre JGZ Kennemerland, we’re looking at how the D-score can contribute to the care provided by Youth Health Care. TNO studied the implementation of the D-score in practice at a number of locations as part of a pilot. This showed that the D-score can help Youth Health Care providers when interacting with parents. Moreover, the D-score offers more flexibility during the contact moments.

At the moment, the list of questions and milestones from the baby clinic must be completed within a limited age interval. The  D-score removes this step, as it takes into account the difficulty level of each characteristic. As a result, Youth Health Care providers can schedule visits more flexibly. Meanwhile, digital applications have been developed that can be implemented in the various digital record systems at Youth Health Care organisations and that researchers can use.

One such digital application is the 'dcalculator' for researchers. This allows you as a researcher to calculate the D-score very easily for your own data based on scores for developmental characteristics. These developmental characteristics could have been measured with any instrument, e.g., Bayleys, ASQ, GSED or Van Wiechen, et cetera. In addition, TNO has also developed software to calculate the D-score. Moreover, healthcare professionals can be connected to JAMES, a system that makes online calculations using case data.

Further development and expansion

In addition to the phased roll-out of the D-score within the Youth Health Care, TNO is committed to extending the D-score to older children. The D-score now measures the development of children between the ages of 0 and 4. Extending the D-score to older children is currently in development. We're also looking into a D-score for premature infants. as premature birth has a significant impact on later development.

Day-care centres and schools also track children's development, but measurements often can't be compared between these organisations. Translating the measurements into the D-score increases comparability. The D-score also gives parents a broad insight into their child's development. TNO is cooperating with these target groups to find applications of the D-score that fit practical needs.

WHO unit of measurement

The D-score also makes a difference in the health of children worldwide. The World Health Organization (WHO) has accepted and put into use the D-score as a unit of measurement. The Global Scale for Early Development (GSED) instruments use the D-score as the underlying measurement scale. For this purpose, TNO extended the D-score to several commonly used measurement instruments that measure child development.

Using GSED, researchers can track children's development at the population level in a standardised way with culturally neutral and accurate measurements. Understanding differences in early childhood development in different countries is a first, yet important, step in realising the potential of children worldwide.

Added value of D-score in research

A uniform measure of development helps the comparability of child development studies. The D-score makes it possible to compare effects of interventions, even if these measurements were made with different instruments. Using one unit for child development ensures comparability not only between populations and studies, but also between ages within populations and studies.

Will you join us?

If you are interested in our research on child development and the D-score, or want to collaborate with us on further development and/or new applications, sign up for our webinar or don’t hesitate to contact us.

About TNO

Innovation for life

We are TNO. A safer, healthier, and more sustainable life. That's what we are all about. As an independent research organisation, we are the driving force behind innovation. We make knowledge serve the common good. Since 1932, it has been our mission to give the right answers – and to ask the right questions. For the world of today and tomorrow. By combining disciplines and domains, we can tackle the most complex questions. On the road to a better life and a brighter future.