Anatomical variations in the female pelvis and their effect in labor with a suggested classification

Abstract Examination of large series of skeletal material shows that pelves, on the basis of morphology, tend to segregate themselves into groups bearing certain common architectural characteristics. Four major groups have been recognized. On analysis these groups differ sufficiently anatomically to warrant a new classification of pelves. The first group consists of an average form which in respect to the form of the compact pelvis displays the accepted sexual characters attributed to the female sex. This has been designated the "gynecoid" type of pelvis. The second group appears to contain certain features common to the average male pelvis. These pelves are termed "android" types. The third group in many respects bears a resemblance to the pelvic form of the great apes. The term "anthropoid" has been proposed for this special type. The last group is characterized by a broad flat form similar to the simple flat pelvis of other classifications. It is a rare type and bears no resemblance to the great apes or other lower forms. The term "platypelloid" originally proposed by Turner, 18 seems descriptive and satisfactory for classification purposes. These variations in female pelves are not associated with or caused by pathologic processes. The more extreme forms have been long recognized by anatomists, anthropologists, and obstetricians. We have attempted to correlate these observations in order to facilitate the application of this anatomical knowledge to the mechanism of labor. The role played by these pelvic types in relation to ease or difficulty in labor is briefly discussed.