Converting UK national insurance weeks into french trimestres

I know that the french pension will require a national insurance statement from the UK so that the relevant periods can be aggregated with the french periods worked. 52 weeks is clearly 4 trimestres. However how do they convert lesser mounts on the statement into trimestres, For example, I have a particular year on my NI online account which gives 50 weeks credits and says that it counts as a full year. Would the french only count 3 trimestres in this case as I am 2 weeks short of 52? Has anyone had problems with the conversion? Does anyone know exactly what information is provided on a NI statement? Many thanks . Elizabeth