That outside influence could be a run of sicker babies, a problem with management or staffing in 2015/2016 specifically. It could also be the person on trial.
You asked about stillbirths which is why I looked for the data. But that data, like I said, suggests a lower stillbirth rate in 2016 than any other year by a long way.
I am by no means playing down the failings of the COCH with regards to it's stillbirth numbers compared with the national average. I'm just pointing out that it doesn't show the same trend as the neonates and doesn't have any years which standout as unusually high for them.
Perhaps I am missing why you are interested in the stillbirth data? I assumed you were trying to link it to this case somehow, but maybe I am wrong?