Clinical significance of fetal heart rate patterns during labor. V. Variable decelerations.

Among a large series of high-risk patients who had direct electronic monitoring, 330 fetuses presented "variable" decelerations and 598 had no decelerations. Among those with variable decelerations, there were 18 who presented such associated fetal heart rate (FHR) alterations as tachycardia, fixed baseline, and slow recovery ("hypoxic components"). The fetal outcome, as well as the characteristics of FHR patterns, were compared among the three groups. Baseline changes were significantly higher among pure variable decelerations and still higher among those having variable decelerations with hypoxic components. Likewise, one- and five-minute Apgar scores were significantly lower in that order. Only 4 per cent with no decelerations had clinical fetal distress while 23 per cent with variable decelerations and 78 per cent of those with variable and hypoxic components had distress. Neonatal death was higher among groups with variable decelerations. Premature rupture of membranes seemed to be the only clearly different (and probably influencing) clinical condition, being higher among the group with variable decelerations. Variable decelerations ("cord patterns") are associated with a relatively high rate of depressed infants. This problem is much worse when elements characteristic of hypoxia are identified in FHR tracings. The degree of drop in FHR frequency is not among those elements so identified. It is thus possible to prevent significant fetal deterioration by meticulous analysis of FHR tracings and active management when "late" components are identified on variable decelerations.