Among the 17 studies identified, 9 included anencephaly and 15 included spina bifida. Nine were from Europe, six were from North America, and one each was from South America and Asia. The overall frequency of TOP following prenatal diagnosis was 83% for anencephaly (range, 59-100%) and 63% for spina bifida (range, 31-97%). There were insufficient data to stratify the results for anencephaly; TOP for spina bifida was more common when the prenatal diagnosis occurred at less than 24 weeks' gestation, with defects of greater severity, and in Europe versus North America.
Because underascertainment of birth defects might be more likely when the pregnancy ends in TOP and TOP is associated with fetal characteristics, selection bias is possible in epidemiologic studies of anencephaly or spina bifida. © 2012 Wiley Periodicals, Inc.
I thought the conclusion was interesting.
Since doctors don't generally do studies on babies who are NOT aborted, there may actually be fewer abortions of anencephaly and spina bifida than we know.
Birth Defects Res A Clin Mol Teratol. 2012 Oct 25. doi: 10.1002/bdra.23086. [Epub ahead of print]Pregnancy termination following prenatal diagnosis of anencephaly or spina bifida: A systematic review of the literature.
National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia; Department of Epidemiology, Emory University, Atlanta, Georgia. email@example.com.