50 Patients weighing between 45 and 114 kg underwent standardized computed tomography of the pelvis. Fat compartments from inside and outside of the small pelvis were assessed quantitatively by means of tracing the fat tissue borders and planimetry. Fat compartments within the small pelvis showed a rather weak correlation with body weight and the so called Rohrer-Index as a weight/height-Index, correlations with the latter being slightly better. From the fat compartments within the single levels the functional reduction of birth channel diameters caused by fat tissue was calculated for. The weight/height-index dependent increase of space demand within the birth channel was rather pronounced at the pelvic brim becoming slighter when reaching mid-pelvis or even pelvic outlet. Hence, the common assumption can no longer be maintained, that adiposity necessarily causes soft tissue dystokia due to larger fat compartments within the small pelvis.