The association of sex ratio anomalies with pyloric stenosis.

Published family data were examined for evidence of aberrant sex ratios in relatives of pyloric stenosis index cases. An excess of males over females was found among unaffected members of sibships in which there occurred more than one case of pyloric stenosis. The male excess among affected members of these sibships did not differ from that among index cases without affected sibs. An unusual frequency of spontaneous abortions in these subships, which might account for the observed excess of males, was not observed. No evidence was found of sex ratio anomalies in other classes of relative of pyloric stenosis index cases, whether or not the index cases had affected sibs.