Children of diabetic mothers may have some protection against developing diabetes themselves because of their exposure to the mother before birth, a study suggests.

Their immune systems may be affected before birth in a way that makes them less likely to develop diabetes than children of diabetic fathers are, the study's authors say.The study dealt with insulin-dependent diabetes - the kind that requires daily insulin shots.

Children of diabetic mothers run a higher diabetes risk than those of normal mothers, but by one estimate they are only a quarter as likely to develop diabetes as are children of diabetic fathers.

Until recent decades, children of diabetic mothers were more likely to be stillborn or die as newborns than were children of diabetic fathers. Some researchers had speculated the early deaths may have culled out children who would later have developed diabetes, thus lowering the diabetes rate among survivors.

But the new study found no support for that speculation, because it showed that the rate of such early deaths in 1,602 pregnancies was unrelated to the diabetes rate in the survivors.