Abdominal electrocardiography in intrapartum fetal heart rate monitoring.

Abdominal fetal electrocardiography (AFECG) as a means of intrapartum fetal heart rate (FHR) monitoring was studied in 700 consecutive labors in a small hospital. Sixty-eight pregnancies were excluded from the study because of the elective cesarean section or because labor was too short for electronic monitoring. AFECG succeeded (at least 30% of fetal heart intervals obtained) throughout labor in 99 of 632 monitored labors (16%). Ultrasound was needed in six cases (1%). The rest (527) were monitored first with the use of AFECG, and later with the use of direct FECG. The mean beat-to-beat variation of FHR (differential index) during last two hours of labor measured from AFECG signal was similar to that measured from AFECG and direct FECG. Hence the same reference values of the differential indices for both methods can be used. The mean long term variation (interval index) measured from AFECG was lower than that measured from abdominal and direct FECGs consecutively. Ultrasound is rarely needed during labor, and it should be avoided except in breech presentations, in association with low placentas and twins, if recording of AFECG fails.