Five-Level Classification of Intrapartum Fetal Heart Rate Patterns

The National Institute of Child Health and Human Development has defined three categories of intrapartum fetal heart rate patterns

• Category I     Normal
• Category II    Indeterminate
• Category III   Abnormal

Jackson M and coworkers reviewed the fetal heart rate data and newborn outcomes of women in term labor. They found the category I fetal heart rate pattern to be the most common during labor occurring 77.9% of the time. The category II pattern occurred 22% of the time during labor,  and the category III pattern occured rarely, only 0.004% of the time during labor.

There has been some concern that the non specific nature and large number of fetal heart rate patterns within category II diminishes its usefulness as an indicator of fetal condition. Considering the high likelihood of category II fetal heart rate patterns during labor a better system for evaluating the significance of these patterns might help in reducing the number of cesarean sections performed for nonreassuring fetal status. The classification developed by Parer and Ikeda may be a step in the right direction.

The classification system developed by Parer and Ikeda is  a color coded, five-category scheme based on published outcome risks related to specific fetal heart rate characteristics. The Parer and Ikeda  system essentially divides the indeterminate category into three additional risk levels and considers  the depth and length of the decelerations in evaluating the risk for the development acidemia.

The chart below  is a condensation of the Parer and Ikeda Five-Level Classification of intrapartum fetal heart rate patterns including recommended actions.

Click to open chart in new window

REFERENCES
Macones GA et al., The 2008 National Institute of Child Health and Human Development Workshop Report on Electronic Fetal MonitoringUpdate on Definitions, Interpretation, and Research Guidelines Obstetrics & Gynecology 2008;112:661-666 PMID:18757666

Jackson M, et al. Frequency of fetal heart rate categories and short-term neonatal outcome. Obstet Gynecol. 2011 Oct;118(4):803-8.PMID:21897312

Parer JT, Ikeda T.A framework for standardized management of intrapartum fetal heart rate patterns. Am J Obstet Gynecol. 2007 Jul;197(1):26.e1-6.PMID:17618744

Parer JT, Hamilton EF.Comparison of 5 experts and computer analysis in rule-based fetal heart rate interpretation.Am J Obstet Gynecol. 2010 Nov;203(5):451.e1-7. Epub 2010 Jul 15.PMID: 20633869

Barber EL, et al. Indications contributing to the increasing cesarean delivery rate.
Obstet Gynecol. 2011 Jul;118(1):29-38. PMID:21646928