FIELD : medicine.SUBSTANCE : invention relates to obstetrics. Pregnant woman' s position on a gynecological chair is used to define the size of a large pelvis using a Martin' s tatomer. Distance between anterior superior left and right anterior cusps. Distance between anterior superior ostium of right or left iliac bone to lower edge of pubic ligament. Angle of the pubic arc is calculated according to the claimed formula.EFFECT : method enables accurate determination of the angle of the pubic arch in pregnant women by evaluating the most significant distances.1 cl, 1 dwg, 3 ex