[Seasonal incidence of congenital hip dislocation. A risk factor].

The congenital dislocation of the hip stational variation frequency is a known anecdotical data in various screening, but its etiology is unknown. Several authors had reported an increase of CDH during fall or winter time. The theory that they support for this finding is the wear use in some countries for the newborn, inducing extension and approximation of the limbs, which could justify the hip dislocation. Another etiological factors proposed by some authors is the climatical influence in mothers hormonal secretion. We have studied 33,000 alive newborns with a CDH frequency about 9.78 per thousand. The new fact that we report is an increase of CDH cases during springtime, without parallel increase in births. The hypothesis we support is: stational variations of CDH is not caused by mechanical factors instead there are another unknown agents. Nevertheless we advocate the springtime as a "risk factor" in our region.