BACKGROUND: The purpose of this study was to clarify the spectrum of congenital constriction band syndrome (CBS) and associated anomalies and mortality in Finland. 

METHODS: Register-based data were analyzed for children with congenital constriction bands in upper and lower extremities as a part of an ongoing study on 419 upper limb defects and 171 lower limb defects occurring among 753,342 births in Finland during 1993 to 2005. 

RESULTS: A total of 71 cases with limb CBS were identified during the 13-year study period. The birth prevalence was 0.9 per 10 000 births (1:10 600). Infant mortality was 4.6% (3/65) and perinatal mortality 12.7% (9/71). In 35 cases (49%) only upper limbs were affected and in 13 cases (18%) there were constriction defects only in lower limbs. In 23 cases (32%) both upper and lower limbs were involved. None of the cases associated with a known syndrome. However, in 21 cases (30%) the child had other anomalies associated with constriction rings: pes equinovarus in 8/21, cleft palate in 5/21, congenital heart defect in 6/21, and other anomalies in 14/21. Eighteen (25%) had low birth weight, 22 (31%) were born preterm, and 8 children (11%) were small for gestational age. Children with associated anomalies showed higher mortality, shorter duration of gestation, and lower birth weight. 

CONCLUSIONS: CBS is rare and comprises approximately 12% of all congenital upper limb defects and 14% of lower limb defects. Other skeletal and nonskeletal anomalies are present in 30% of the affected children, suggesting a possible genetic etiology. More detailed characterization of the children with associated anomalies may shed light to the pathogenetic mechanisms of this syndrome. 

LEVEL OF EVIDENCE: Population-based register study/II.