[Polydactyly in 26,670 consecutive births. The clinical characteristics, prevalence and risk factors]

The purpose of the study is to determine the prevalence of polydactyly, its clinical characteristic and its association with some risk factors.

A retrospective, case-control study, of 45 newborn with polydactyly and their controls, in 26,670 consecutive births in the Nuevo Hospital Civil de Guadalajara, with 20 weeks or more of gestational age, and birth weight greater than 500 g, since November of 1988 to October of 1992. The information were obtained from the database of the Congenital External Malformation Register, carried out by the University of Guadalajara. The prevalence of polydactyly was obtained and clinical characteristic were documented. Continuous variables were compared using t Student test. For discrete variables, analysis were carried out using X2 test and the odds ratio.

The prevalence of polydactyly was of 1.73 x 1,000 alive newborn. The polydactyly of the hands in 26 newborn; preaxial in five and 21 was postaxial. The polydactyly in the foot was present in 19 newborn. The only statistics differences with control group were: low length and the antecedent of other malformation in the family.

The found prevalence is different to the one informed in the literature. The association with antecedent of another malformation in the family, support the role of hereditary factors in etiology.