Birth prevalence for congenital limb defects in the northern Netherlands: A 30-year population-based study

Background: Reported birth prevalences of congenital limb defects (CLD) vary between countries: from 13/10,000 in Finland for the period 1964-1977 to 30.4/10,000 births in Scotland from 1964-1968. Epidemiological studies permit the timely detection of trends in CLD and of associations with other birth defects. The aim of this study is to describe the birth prevalence of CLD in the northern Netherlands.

Methods: In a population-based, epidemiological study we investigated the birth prevalences of CLD for 1981-2010. Data were collected by the European Surveillance of Congenital Anomalies in the northern Netherlands (EUROCAT-NNL). We excluded malpositions, club foot, and dislocation/dysplasia of hips or knees. Trends were analysed for the 19-year period 1992-2010 using chi(2) tests, as well as CLD association with anomalies affecting other organs.

Results: The birth prevalence of CLD was 21.1/10,000 births for 1981-2010. There was an overall decrease in non-syndromic limb defects (P = 0.023) caused by a decrease in the prevalence of non-syndromic syndactyly (P <0.01) in 1992-2010. Of 1,048 children with CLD, 55% were males, 57% had isolated defects, 13% had multiple congenital anomalies (MCA), and 30% had a recognised syndrome. The upper: lower limb ratio was 2:1, and the left: right side ratio was 1.2:1. Cardiovascular and urinary tract anomalies were common in combination with CLD (37% and 25% of cases with MCA). Digestive-tract anomalies were significantly associated with CLD (P = 0.016).

Conclusions: The birth prevalence of CLD in the northern Netherlands was 21.1/10,000 births. The birth prevalence of non-syndromic syndactyly dropped from 5.2/10,000 to 1.1/10,000 in 1992-2010.