Are all infants of diabetic mothers “macrosomic”?: Authors' reply

SIR,-While applauding Dr R J Bradley and colleagues for trying to break away from the simplistic concept of diabetic mothers being either macrosomic or not,' I do have some reservations about their data. They included a few women with gestational diabetes, who themselves form a heterogenous group. They did not need to swell their numbers in this way, and thus open themselves to criticism, since they had enough women with insulin dependent diabetes in their study. A more important reservation concerns their choice of controls. They seem to have contrasted their diabetics with the total population of women delivering in their district. I run a similar clinic and would find this comparison invalid for my population. I suspect it is for theirs as well for two main reasons. Firstly, their diabetic women will be mainly from outside their district and are probably of a higher social class than their indigenous hospital population and so one would expect them to have heavier babies. Secondly, their hospital population probably contains a higher proportion of nonwhite mothers than their diabetic population, which again would make the diabetic women seem to have heavier babies for reasons unrelated to their diabetes. Finally, I was surprised not to see a small increase in low birthweight babies among mothers with diabetic vascular disease (White's class F,R), a finding in my own clinic.