Shoulder dystocia: Should the fetus weighing ≥4000 grams be delivered by cesarean section?

A total of 75,979 women who were delivered vaginally in the period 1970 to 1985 were stratified into diabetic and nondiabetic groups. Overall, the incidence of macrosomia (≥4000 gm) was 7.6% ( 5674 74390) in the nondiabetic group and 20.6% ( 328 1589) in the diabetic group. Patients were further subdivided by weight categories at 250 gm intervals. Eight percent of shoulder dystocia occurred in the diabetic group when fetal weight was ≥4250 gm. In contrast, 20% of shoulder dystocia in the nondiabetic group could have been prevented by elective cesarean section when the fetal weight waS ≥4500 gm. Furthermore, logistic regress on analysis demonstrated that birth weight, diabetes, and labor abnormalities were the principal contributors to shoulder dystocia. Elective cesarean section is strongly recommended for diabetics with fetal weights ≥4250 gm, and trial of vaginal delivery for nondiabetic fetuses with weights ≥4000 gm is recommended. In all cases the clinician must be watchful for labor abnormalities in macrosomic fetuses.