Screening of the fetal heart rate in early labour

The fetal heart rates (FHR) of 588 women admitted in labour, or in early labour after induction, were screened for up to 60 min (average 17 min) using computerized numerical analysis. Decelerative records with normal FHR variation occurred in eight (1.4%) and were not associated with acidaemia or depression at birth. Forty women (6.8%) had fetuses with a reduced FHR variation. They were more likely to be in spontaneous labour, to be at an earlier gestational age, and to be delivered operatively for fetal distress of babies that were more hypoxaemic and acidaemic. However, none of the fetuses with the least variable FHR patterns required resuscitation at birth or special care. The results of the screening procedure were not fully concealed and could have influenced clinical management. This is unlikely to have caused the associations that were observed, but could have reduced an association between low FHR variation and poor outcome. We conclude that there is a basis for a randomized controlled trial of FHR screening in early labour, but that this would need to be large (more than 10,000 patients) to test the benefit of detecting the most sinister pattern (decelerations with reduced variation) of which only one example was found in this study.