As smoking status is recorded at two points in time only, the data will not show if mothers were smoking throughout the duration of their pregnancy, or how frequently they smoked.
Gan mai ar ddwy adeg yn unig y cofnodir statws smygu’r mamau, nid oes modd i’r data ddangos a fu’r mamau’n smygu drwy gydol eu beichiogrwydd, nac ychwaith pa mor aml y buont yn smygu.