Estimated fetal weight not a guide for cesareans. (Preventing Shoulder Dystocia).

ASHLAND, ORE. -- Estimated fetal weight can be used as a guidepost in directing obstetric management of diabetic and nondiabetic patients but should not be used to dictate cesarean sections, researchers determined in a 4-year study.

The investigators studied the usefulness of a departmental policy that urged discussion of the option of a cesarean section in nondiabetic pregnant women with an estimated fetal weight (EFW) of at least 4,500 g and in diabetic pregnant women with an EFW of at least 4,250 g. Births were tracked that occurred while that policy was in effect from January 1996 to December 2000.

Among 118 nondiabetic women with an EFW of more than 4,500 g, 62 elected to have a cesarean section for macrosomia. They differed from the 56 who opted for a trial of labor in that they had lower parity, higher EFW and higher actual birth weight, Dr. Patrick M. Mullin said at the annual meeting of the Pacific Coast Obstetrical and Gynecological Society.

Vaginal delivery was accomplished in 34 of 56 of those who labored, and there were two shoulder dystocias. The remainder bad cesarean sections performed during labor.

If all of the women in this group had undergone cesareans, then 32 unnecessary operations would have been performed to prevent two shoulder dystocias, Dr. Mullin said.

Analysis of the other group shows that 28 of 62 women who elected to undergo cesareans delivered babies who were smaller than their EFW.

Four delivered infants who weighed less than 4,000 g, and 24 delivered infants weighing 4,000-4,500g. Thirty-four had infants who weighed more than 4,500 g, he added.