Sir.—I applaud the attempt by Wiswell et al1 to estimate the current incidence of major congenital neurologic malformations. One factor may have caused an underestimate of the reported incidence. Many military posts are located in remote locations. When these malformations are discovered in utero, the mother is usually given the option of delivering in the nearest civilian institution with appropriate treatment capabilities or traveling a long distance to a major military medical center. Often, travel to the military facility is very inconvenient and requires a separation of the family. Many mothers elect to deliver in a civilian hospital. These patients are apparently not accounted for in the study, since it only contains infants born in US Army hospitals. The true current incidence of these malformations is probably higher then estimated in the study.