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SALT LAKE CITY — Fetal heart rates are monitored to indicate a baby's overall health. But according to a new study by doctors with Intermountain Healthcare, the heart rates are too often considered indeterminate and therefore shouldn't be used to make decisions regarding emergency cesarean deliveries.
Maternal-fetal medicine specialists believe fetal heart rate patterns may not be a good indicator of a baby's health, and may lead to such unnecessary interventions and higher health care costs.
"We're trying to create a better road map for labor," said Dr. Marc Jackson, an OB-GYN at Intermountain Medical Center and principal researcher on the study, which is published in the October issue of Obstetrics and Gynecology. "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."
Heart rate patterns were monitored using a three-tiered classification system, developed in 2008 by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. However, the study states that the system has been in need of an update because reliance on the various classifications has tempted more doctors to take possibly unnecessary precautions, including an increasing number of C-section and forceps deliveries.
While the majority of the 48,444 babies born at 10 Intermountain hospitals during a 28-month study period showed normal heart rate patterns throughout delivery, some of those, about 39 percent, changed during the final two hours of delivery. Those babies then fell into a mid- range clinical definition, making their heart rate pattern significance uncertain, and health factors basically "indeterminate."
Abnormal or rare heart rate patterns, which typically indicate a problem, were noticed in only 0.1 percent of the patients studied, and resulted in admission to the neonatal intensive care unit about half the time.
According to study results, the vast majority of babies born under the "indeterminate" category had no short-term problems after delivery and only 0.2 percent of them required admission to the NICU, which means that using those uncertain patterns as an indicator of fetal health is an unreliable method, researchers say.
Health outcomes for babies tend to rely more on how long their heart rates fall within a specific category and less on whether they do.
Without a good map to guide them during the critical hours of labor and delivery, doctors and nurses must play a guessing game — one that will almost always spur them to act with caution.
Jackson said the next step is to further classify the heart rate patterns in the uncertain, middle category, "to determine which ones are more predictive of a baby that's sick and one that's healthy."
"When we know that, we will be able to make better decisions for both the mother and her baby," he said.