Alaska infants are twice as likely to be born with major birth defects as infants in the U.S. as a whole, according to a new study by the state Department of Health and Social Services — and officials are at a loss to explain why.

Rates were especially high among Alaska Natives, but all races of Alaskans exceed national rates for "major congenital anomalies," according to the review of seven years of data (from 1996 through 2002) drawn from the Alaska Birth Defect Registry.

Birth defects were reported in 10.5 percent of all live births among Alaska Natives, compared to 6 percent for all Alaskans and 4 percent for white Alaskans. Among all Americans, the rate was 3 percent.

Alaska public health officials have long suspected that infants here suffer higher rates of birth defects, This is the first time officials have felt confident enough of the data to publish, said Janine Schoellhorn, an analyst in the state's Maternal and Child Health Epidemiology unit.

Congenital heart problems lead all other types of birth defects in Alaska, just as they do nationwide, the study reported. Chief among those were "atrial septal defects" and "ventricular septal defects" involving holes in the walls of the heart.

Alaska also posted higher than average rates of less common birth defects, such as cleft palates (two times the national average), fetal alcohol syndrome (four times the national average), and Hirschsprung's Disease, characterized by enlarged colons due to bowel obstructions (six times the national average).

Read the full story at adn.com.