Heart rate patterns may not be a good indicator of a baby's health, and may actually lead to unnecessary interventions and higher treatment costs, say specialists at Intermountain Medical Center. "We're trying to create a better a road map for labor," says Marc Jackson, principal investigator on the study. "For years we've used the fetal heart rate to try to identify problems, but it's not a very good map because we have so many babies in an 'indeterminate' category."
To clear up that uncertainty, Jackson studied fetal heart rate patterns from more than 48,000 labor and delivery cases at 10 hospitals over a 28-month period. The fetal heart rates were then classified and the findings published in the journal Obstetrics and Gynecology.
Three categories were considered: Category I heart rate patterns are considered normal, and, as a rule, do not indicate fetal stress. Category III patterns are abnormal and rare, and usually indicate a problem. Category II patterns are considered indeterminate.
Jackson and his co-researchers examined the time babies spent in each of these categories and neonatal outcomes. The fetal heart rate patterns were classified as category I 78 percent of the time, as category II patterns 22 percent of the time, and as category III only very rarely - 0.004 percent of the time.
But, when looking at the data for just the final two hours of delivery, the numbers changed. The data show that category I rates decreased to 61 percent, while category II rates increased to 39 perent, and category III rates increased to 0.006 percent.
Category II fetal heart rate patterns showed up most often, occurring in 84 percent of all labors. The researchers also found that the amount of time spent in category II increased in the two hours before delivery. But regardless of those statistics, the vast majority of category II babies had no short-term problems after delivery. This suggests that using category II heart rate patterns as an indicator of fetal health is an unreliable method, Jackson claims.
"Our next step, obviously, is to sort out those patterns in Category II to determine which ones are more predictive of a baby that's sick and one that's healthy," says Jackson. "When we know that, we will be able to make better decisions for both the mother and her baby."
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Source: Intermountain Medical Center
