However, in all years prior to 2020, more than 90% of records had valid data for smoking status at birth, across nearly all health boards.
Fodd bynnag, ym mhob blwyddyn cyn 2020, roedd mwy na 90% o’r cofnodion yn cynnwys data dilys ar gyfer statws smygu ar adeg yr enedigaeth, ar draws bron bob un o’r byrddau iechyd.