Quantification of obstetric traction.

Measurements of factors involved in the degree of traction exerted during obstetric cases were carried out. Bovine material force was approximately 150 lbs. Maximum manual effort would be approximately four times this and mechanical traction would be at least 50 per cent higher again. A workable maternal fetal ratio was established for use in cases of fetal oversize. Possible quantification of other factors is also discussed.