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FAQs for Integrators

In our documentation, we use the term Integrator to refer to a person or team who is integrating the API into a product or service. We also recognise the term 'customer'. This distinguishes 'Integrators' from 'clients' (by which we mean software which consumes the API), and 'developers' (by whom we mean those who are developing the Digital Growth Charts project)

Information about the dGC client products

Information for dGC Developers

Q: Can we self-host the API?

A: Technically yes. However, there are several important considerations, of which the downsides outweigh any benefits.

We have open-sourced the API to align with our policy on transparency and clinical safety. However, we advise you do not self-host it. Only the version deployed and managed by the RCPCH team is warranted to be correct.

Self Hosting - Clinical Safety Risk

TL;DR: Don't self-host in production. Use our warranted API.

The only version of the Digital Growth Charts API which is warranted to be correct for clinical use is that which is served by the RCPCH itself from our API endpoint at

For reasons of transparency, equity-of-access and safety, we have made it possible to use our open-source code to set up a server providing Digital Growth Charts API calculations. However, we strongly advise against doing this, except for testing, verification, development purposes or research (which is not for academic publication).


By self-hosting, you would not have a warranty from the RCPCH: you are liable for misconfigurations in the server leading to clinical issues. To ensure safe service with the complexity of Growth Charts, you likely require large amounts of statistical, clinical and technical consultancy.

You must understand and accept that any version of this API running outside our controlled environment must have been:

  1. Independently technically-assured, such that the platform, deployment, and modifications are secure, safe, and reliable.

  2. Independently clinically-assured, such that the application is safe and has a qualified Clinical Safety Officer, a Clinical Safety Management File, and is fully compliant with DCB0129 and DCB0160.

  3. Registered with the MHRA as a Medical Device (for UK deployment) and EU MDR, with Declaration of Conformity (for EU deployment).

For this reason, we STRONGLY recommend you DO NOT SELF-HOST any of our platform, but instead use the hosted (and attractively-priced) Digital Growth Charts API platform. Self-hosting means your organisation is fully liable for any errors in calculation, deployment, or functioning. We will not provide any free support for self-hosting organisations.

RCPCH On-Premise Hosting Service

The RCPCH offers an 'on-premise' managed service which may suit some customers requiring the service to be hosted within their own data centre, or on their own cloud infrastructure. Find out more about pricing.

By using the RCPCH-provided API, you avoid all that requirement and use our commodity server.

Q: Is entering a gestational age mandatory?

A: Gestational age is not mandatory for the API to return a value. If not supplied, the child will be assumed to be born at 40 weeks. For the UK-WHO charts, the standard term references will be used for calculations and charts.

From a DPCHR implementer perspective, if a birth notification has not flowed into the DPCHR, suppliers will need to require parents to enter it.

Q: What development effort is required to integrate this API into an app or Electronic Patient Record?

A: Minimal development is required. The tricky stuff (calculating centiles from complex statistical tables, selecting the correct UK90 or WHO references for age, and gestational age correction) is all done for you. The data returned will be the correct centiles, which can be displayed to the user.

Producing a visual ‘growth chart’ with this data is a little more involved, however, we have simplified the process by building API endpoints which return coordinate data from which to build the chart lines. We’ve also made an open-source library which takes that source data and makes a chart for you. This is built in React and is MIT licensed, but if you are using another technology, you can inspect the source to build your own client.

We are keen to build a ‘catalogue’ of chart clients, so other open-source clients are very welcome. We will also help you build and test them!

Q: Is corrected gestational age passed back by the API?

A: Yes, corrected age is passed back by the API, if a gestational age is included in the request.

NOTE: The API can only correct for gestational age if a gestational age has been supplied!

This correction is applied throughout the life course. (In the past the correction was only applied to 1 or 2 years depending on the degree of prematurity. This is no longer the case, following an RCPCH dGC Project Board decision. It is trivial to have the computer correct throughout the life course, so we made this the default. Uncorrected age is still available in the API response, if required.)

Q: Does my application need to validate inputs?

A: The API has validation and error handling for out-of-range requests, but it is good practice for the front-end software to also reject input values outside the valid range since the user will receive immediate feedback from your application.

Q: Is there a source from where we can get a list of extreme input values to use for our validation?

A: Yes, we have included one in our source code: Validation Constants. This is used internally to validate API inputs, as well as by the internal rcpchgrowth Python module to validate inputs to the Measurement class.

Q: Would it be good enough to plot the returned centile values on a pre-prepared image of a growth chart?

A: Maybe. It would depend on the implementation.

Images of charts are definitely not good enough for calculating a centile from, although many General Practice software packages currently do it this way. Plotting on an image is a hack, and it's why we had to create the API in the first place. However, since we are calculating the centiles for you, the chart is only for displaying the trend. An image could be used, but we generally advise against it.

It is very easy to accidentally offset or incorrectly scale images, leading to some correctly plotted points, but others not. The best practice is to always use the same vector graphic tooling to both construct lines and plot the points, avoiding offsets/scaling inaccuracy. If you use an image (against our advice), you must ensure the correct one is selected for the presented data. More, you must ensure scaling and offset are not just programmed to be correct, but also clinically tested to be correct!

We would in every situation recommend using the React Chart Component to render the chart. It is open-source, and can be used as a reference implementation if you wish to build your own.