SEATTLE -- Investigators don't know why more babies in south-central Washington suffer a deadly birth defect compared to the rest of the state.
Anencephaly is a fatal birth defect which results from incomplete formation of the brain during the first month of pregnancy. The Washington State Department of Health began investigating potential causes of the defect in Yakima, Benton, and Franklin counties after discovering these areas had an unusually high number of cases.
"It's a rare but really bad condition," said Donn Moyer, media relations manager for the Washington Department of Health. "It's fatal and tragic, so we wanted to see if there was some cause we could find to have mothers be aware of it."
But after examining medical records from 2010 to 2013, investigators have found no common exposures, conditions, or causes for anencephaly. There are no known significant differences between women who had healthy pregnancies and those affected by anencephaly in the area.
Typically, one or two anencephaly cases would be expected in about 10,000 annual births, but there have been about eight cases per 10,000 births in Yakima, Benton, and Franklin counties.
Anencephaly and the related spinal cord disorder spina bifida are often caused by a lack of the B-vitamin folic acid in the mother's diet. Other factors include certain medications, diabetes, pre-pregnancy obesity, or previously having a child with a neural tube defect.
Investigators considered family history, pre-pregnancy weight, health risk behaviors such as supplemental folic acid and medication use, and whether the woman's residence received drinking water from a public or private source, but found no cause for the increase in cases.
Although the number of affected pregnancies was large for this area, Moyer said larger numbers are often needed to identify causes. Medical record reviews might not have captured all information, preventing a cause from being identified.
Investigators report the higher than expected number of anencephaly births in the region could be coincidental. Still, Moyer said state health officials will continue monitoring births in the region through 2013 to see if the elevated number of affected pregnancies continues and if more can be learned about causes.
Health officials recommend women of childbearing age follow the U.S. Preventive Services Task Force recommendation of taking 400 to 1,000 micrograms of folic acid daily, either from foods fortified with folic acid or a supplement. They also advise seeing a health care professional when planning a pregnancy or as soon as pregnancy is recognized, and making sure to provide a list of all medications and nutritional supplements being used.
Women who are pregnant or planning pregnancy should be sure drinking water from private wells is tested at least annually for nitrate and bacteria. If levels exceed standards, an alternate source of drinking water should be used.