This is largely due to Hywel Dda not supplying any data for smoking at birth and Cwm Taf Morgannwg having relatively low data completeness.
Nodwch fod data ar gyfer Blaenau Gwent, Pen-y-bont ar Ogwr, Ceredigion, Sir y Fflint, Gwynedd, Sir Fynwy a Rhondda Cynon Taf wedi'u hatal oherwydd maint sampl annigonol i ddarparu data o ansawdd.