Analysis of fetal heart rate on-line at 32 weeks gestation

Summary

Antenatal fetal heart rate (FHR) patterns were screened in 634 women with singleton pregnancies at 32 weeks gestation using a microprocessor on-line. The duration of the record was adjusted according to its character, varying from 10 min with high FHR variation (39% of records) to 45 min with low variation (4.7%). The average duration was 16.7 min. Of the 30 fetuses with the lowest FHR variation (<5th centile), 19 (63%) had a normal outcome. Of the 11 with an abnormal outcome five were born 38 weeks; six were born by caesarean section at 32–34 weeks, resulting in an increased incidence in the group. Analysis of the numbers of accelerations, of decelerations, of episodes of high FHR variation or of fetal movements did not improve long-term prediction. It was concluded first, that antenatal FHR monitoring for up to 45 min at 32 weeks gestation had no long-term predictive value; and second, that 3% of our obstetric population have unreactive FHR traces at this age, with a normal outcome. This does not imply that consecutive antenatal records on the same high-risk patient at short intervals are not valuable clinically.