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FAQs for Integrators

In our documentation we have used 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 is to distinguish 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 which we believe would more than negate any saving made.

We have open sourced the API in order to align with our policy on transparency and clinical safety, however we advise that 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 While we have, for reasons of transparency, equity-of-access and safety, made it possible to use our open source code to set up a server providing Digital Growth Charts API calculations, we specifically and strongly advise against doing this, except for testing, verification, research (which is not for academic publication) or development purposes.

If self-hosting you would not have a warranty from RCPCH and your organisation would therefore be liable for misconfigurations in the server leading to clinical mishap. Growth Charts are complex, and in order to assure your service is safe, you are likely going to need a large amount 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 that 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 it is not supplied then the child will be assumed to be born at 40 weeks and therefore 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.

  • [DPCHR]: Digital Paediatric Child Health Record
  • [DCB0129]: (Data Coordination Board) Standard 0129
  • [DCB0160]: (Data Coordination Board) Standard 0160

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 on is a little more involved, however we have tried to make the process as easy as possible by building API endpoints which return the coordinate data from which to build the chart lines, and also we’ve made an open source library which takes that source data and makes a chart for you. It’s built in React and is MIT licensed, but if you are using another technology then you can inspect the source and use that to build your own client.

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

Q: Is corrected gestational age passed back by the API, or do implementers have to calculate it?

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


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

This correction is applied up to the corrected age of 1 year for preterm children born above 32 weeks, and to the corrected age of 2 years for preterm children born below 32 weeks, which is accepted standard practice among paediatricians.

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 that are out of range since this feedback can be shown to the user, by the 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 what is used internally to validate API inputs and also used 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 GP software packages do it this way, it's poor practice and it's why the API needed to exist in the first place. BUT, since we are calculating the centiles for you, then the chart is only for displaying the trend. An image could be used, but we would advise against it generally.

The problem with images is that it is very easy to accidentally have an offset or scaling error that means that some plotted points are in the right place, and some are not. Best practice is always to use the same vector graphic tooling to both construct the lines and plot the points, to avoid offsets/scaling inaccuracy. If you are using an image (please don't) then you must ensure you're selecting the correct one for the data you're presenting, and that the scaling and offset is not just programmed to be correct, but clinically tested to be correct!