Rates were also markedly higher in mothers from White and Mixed ethnic backgrounds, with very few mothers from Black or Asian backgrounds recorded as smokers.
Roedd y cyfraddau hefyd yn sylweddol uwch mewn mamau o gefndiroedd ethnig Gwyn a Chymysg, gydag ychydig iawn o famau o gefndiroedd Du neu Asiaidd wedi'u cofnodi fel smygwyr.