Infants with congenital limb reduction registered in the Swedish Register of Congenital Malformations.

Limb reduction defects reported to the Swedish Register of Congenital Malformations 1965-1979 have been analyzed from a monitoring point of view. The infants were first studied with respect to the site of reduction malformation and the simultaneous presence of more than one such reduction site. Reductions often occurring together were thought to have a common pathogenesis (etiology) and were therefore treated as one unity although some such groups (e.g., radial longitudinal reductions) are probably heterogeneous. The material was therefore divided into 11 subgroups; the eleventh is represented by infants with more than one unrelated reduction. Maternal age distribution was approximately normal. There is a male preponderance of all reduction types. In the whole group, 20% of the infants died perinatally, but this percentage was higher for some groups (e.g., amelia/phocomelia) than for others (e.g., amputations and unspecific hand/foot reductions). In more than 30% of the infants, nonlimb malformations were also present. Such infants showed the highest death rate of all. The infants had a lower than expected birth weight (gestational length was not known). The time trends for the various subgroups differed. Amelia/phocomelia declined in frequency but the unspecific hand/foot reductions showed a marked increase during the last few years, possibly owing to better ascertainment. The significance of monitoring reduction malformations as smaller subgroups is stressed, as marked changes may occur within a subgroup without a noticeable change in the total number of reductions.