Depends on definitn
Most accept the definition of bds as anatomical abnormalities, large or small, obvious or not that are present at birth.
Some might include gene derived anomalies like extra fingers or metabolic issues like cystic fibrosis
. Numbers for individual defects are easier to come by than inclusive numbers for this reason. (ie.Cleft lip
, down syndrome
) i've seen inclusive estimates from 3-6% for all bd's.