Cluster of Rare Birth Defects Under Investigation
Credit: Ultrasound photo via Shutterstock

Health officials are investigating a cluster of serious birth defects in a region of Washington State, but still have not identified any common factor linked with the cases.

Over the last four years, at least 30 babies in the region have been born with anencephaly, a birth defect in which a child is missing parts of the brain and skull, according to NBC News. The rate of anencephaly cases near Yakima, Wash., is 8.7 per 10,000 births, much higher than the U.S. national rate of 2.1 cases per 10,000 births, NBC says.

The cluster could turn out to be simply a coincidence, but health officials may conduct interviews with parents to look for possible links, NBC says.

Nearly all babies born with anencephaly die shortly after birth, according to the Centers for Disease Control and Prevention. One risk factor for the condition is low intake of folic acid before and during pregnancy, and people in the cluster region are known to have a low rate of folic acid use, NBC says.