Investigation of a Cluster of Neural Tube Defects — Central Washington, 2010–2013

During August 2012, a health-care provider in central Washington alerted the Washington State Department of Health (DOH) about an excessive number of anencephaly births at a local hospital. After examining referral patterns for high-risk pregnancies in central Washington, DOH identified pregnancies affected by a severe neural tube defect (NTD) in a three-county area. Case findings included a review of area hospital discharge records for International Classification of Diseases, Ninth Revision codes 740, 741, 742, or 655.0; vital statistics reports; and perinatology office records. From these sources, 27 confirmed NTD-affected pregnancies occurring during January 2010-January 2013 were identified among women residing in the three-county area. Twenty-three pregnancies were affected by anencephaly, three with spina bifida, and one with encephalocele. The anencephaly rate was 8.4 per 10,000 live births (95% confidence interval [CI] = 4.5-12.0), compared with a national estimate of 2.1 per 10,000 live births (CI = 1.9-2.2). In contrast, the rate of spina bifida was 1.3 per 10,000 live births (CI = 0.3-3.8), compared with 3.5 per 10,000 live births nationally (CI = 3.3-3.7).