[Fetal and neonatal heart rate changes related with the acid-base balance of umbilical cord arterial blood].

The fetal heart rate (FHR) in the last 15 minutes of labor and the neonatal heart rate (NHR) in the first 15 minutes of life were recorded, and their correlation with the acid-base balance of the umbilical cord arterial blood was studied in 62 full-term infants. The one minute Apgar score was 7 or greater in all cases. The cord arterial pH was less than 7.250 in 13 neonates in the low pH group, and it was 7.250 or greater in 49 in the high pH group. FHR patterns during the last 15 minute of labor were classified into three types. The normal type was observed in 32 cases (51%), the severe variable deceleration type in 25 (40%), and the bradycardia type in 5 (9%). In the severe variable deceleration type, 10 cases in the low pH group showed a significantly longer period that of appearance than 15 in the high pH group. All fetuses that had at least one acceleration in the last 15 minutes of labor were included in the high pH group. NHR increased and reached its peak of 192bpm at 2.8 minutes after birth on the average. However, the low pH group showed a significantly higher NHR and a longer period until the peak than the high pH group. The low pH group had a higher NHR-baseline than the high pH group.