Agreement about the terminology and descriptions of fetal heart rate (FHR) patterns (nomenclature) is now well established, largely based on the report of the National Institute of Child Health and Human Development (NICHD) workshop of 1997, but consensus on FHR interpretation and management has been extraordinarily difficult to achieve in US obstetrics. Interpretation deals with the significance for the fetus in terms of risk of potentially damaging metabolic acidemia. It is also now understood that part of this interpretation is recognizing or projecting the probability of a pattern of lower risk of acidemia evolving into one with a higher risk so that timely intervention can occur. Management means how the obstetrical team actually responds to a FHR pattern to minimize fetal metabolic acidemia without excessive operative or other interventions.

Many professional bodies and individuals, particularly overseas, have classified FHR patterns and recommended management approaches (eg, the Royal College of Obstetricians and Gynaecologists, the Society of Obstetricians and Gynaecologists of Canada, and the Royal Australian and New Zealand College of Obstetricians and Gynaecologists and the Japan Society of Obstetrics and Gynecology). For various reasons none of these guidelines has achieved widespread adoption in the United States. There was therefore much enthusiasm for the announcement in 2008 that the NICHD was again convening a meeting to revisit and update the findings of the report published more than a decade earlier.

The subsequent publication endorsed the definitions and the findings of the prior workshop, without making changes in the terminology. The various FHR patterns were classified into categories I (normal), II (indeterminate), and III (abnormal), approximately the same gradations that were used in the clinical statement in the 1997 document. This has been called the 3 tier system, and it was espoused on the basis of simplicity and ease of teaching. These categories have been endorsed in the American College of Obstetrics and Gynecology practice bulletin of 2009.

Unfortunately, category II consists of a vast heterogeneous mixture of patterns, based on variations in baseline rate, variability, and decelerations, and there is little guidance for management of these patterns by obstetrical providers. For example, few would disagree that a FHR pattern with minimal variability and persistent severe late decelerations is more threatening than one with moderate variability and mild variable decelerations, yet both are category II. There cannot be any such management guidance unless category II, containing probably 80% of all variant patterns, is subdivided further.

Subcategorization of this group of tracings was not done on the basis of inadequate evidence, although this conclusion ignores the rich fund of observational studies from the earliest days of monitoring, the 1960s and the 1970s, when data linking various FHR patterns to acidemia were collected. These studies cannot be repeated because it would now be considered unethical by many practitioners to observe some of these patterns without intervention.

The 2008 NICHD report has resulted in a number of reactions from practitioners and investigators. Editorial comments and at least 10 abstracts on the subject have appeared in the United States alone this year. The general conclusion is that category I (normal FHR pattern) may be associated with a somewhat better short-term outcome than category II, but there is no evidence that category II is sufficiently discriminating to assist in FHR management.

There is pressure from obstetrical nurses and certified nurse-midwives (CNMs) in our community hospitals to assist by developing suggestions for management within category II. At least 2 community hospitals in our region have set up such internal guidelines, based on a 5 tier color-coded system.

These locally developed guidelines primarily involve such features as when to inform the physician or CNM, when to request their analysis of the tracing, and when to request their presence at the bedside. Nurses and CNMs would also like to be guided in when they are justified in moving a patient to the operating room or when to call for a good samaritan when the primary obstetrician is not immediately available.

None of this guidance is possible with the vast spectrum of patterns currently included in category II. All of these graded responses are sufficiently intrusive that it is unfair to simply leave them to the individual nurse’s judgment. Obstetricians bear a responsibility for participating in developing such guidelines on an interdisciplinary basis.

There is sufficient information in the literature about the risk of acidemia associated with certain category II patterns, the interplay between FHR variability and decelerations, and the risk that a pattern will progress to category III to set up management plans that can be tested for effectiveness. The espousing of a 3 tier system does not allow this and seems to be a retrogressive step that is likely to impede progress in the validation of specific algorithms.

Against this background, evidence is accumulating that a 5 tier system does relate to degrees of acidemia and fetal damage and, if appropriately rule based, can improve consistency in interpretation among providers. There is also emerging evidence that if taught and accepted hospital-wide, such an approach can reduce newborn metabolic acidemia without increased intervention.

An obvious solution is for official bodies and professional associations to set up a framework that conforms to the currently available data (admittedly limited), which can be tested for effectiveness by eager investigators. The Japan Society of Obstetrics and Gynecology has done this with 5 tiers on a national level and is expecting validation (or the opposite) to emerge from subsequent studies. We in the United States should do the same.