Diabetes increases a pregnant woman's risk for having miscarriages, stillbirths and babies with birth defects. and now, a new study by researchers at Kaiser Permanente shows a disturbing trend.

Dr. Jean Lawrence said, "What we found from 1999 to 2005 is the proportion of women giving birth that already had diabetes before they were pregnant doubled."

She attributes that doubling of diabetes rates primarily to the rise in obesity - especially among minority women.

The study looked at every age, race and ethnic group. but the biggest jump came in pregnant teenagers, who saw a 500 percent increase in diabetes rates in just six years.

The study examined the records of over 175,000 women who gave birth at eleven Kaiser Permanente hospitals in southern California. Two-thirds of all adults, and 15 million children in the United States are obese or overweight.