Limb deficiencies in newborn infants

Objective. The prevalence rate of all types of limb reduction defects in ge neral and those that potentially are caused by vascular disruption in parti cular is needed to provide a baseline for the evaluation of infants who are exposed in utero to teratogens that cause vascular disruption. The objecti ve of this study was to determine this prevalence rate. Methods. All infants with any limb deficiency among 161252 liveborn and sti llborn infants and elective terminations were identified in a hospital-base d Active Malformations Surveillance Program in Boston in the years 1972 to 1974 and 1979 to 1994. An extensive search was made to identify infants who were missed by the Surveillance Program; an additional 8 infants (7.3% of total) were identified. The limb reduction defects were classified in 3 way s: 1) by the anatomic location of the defect, that is longitudinal, termina l, intercalary, etc; 2) for infants with absence/hypoplasia of fingers or t oes, a tabulation of which digit or digits were affected; and 3) by apparen t cause. Results. The prevalence rate for all types of limb deficiency was 0.69/1000 . The apparent causes included single mutant genes, familial occurrence, an d known syndromes (24%); chromosome abnormalities (6%); teratogens (4%); va scular disruption (35%); and unknown cause (32%). Conclusions. A hospital-based surveillance program can be used to establish the prevalence of limb reduction defects, if ascertainment is extended to include elective terminations for fetal abnormalities. An apparent cause ca n be established for most limb defects when the clinical findings are used rather than reliance only on the International Classification of Diseases, Ninth Revision, codes of the discharge diagnoses. The prevalence rate of li mb reduction defects as a result of presumed vascular disruption was 0.22/1 000.