Practice Issues


Study for Determining
Fetal Heart Tone Variability
(reassuring patterns) by Intermittent Auscultation


faith gibson, 
Licensed Community Midwife #041

CPM #96050001,
North American Registry of Midwives


Citations and Excerpts:

Gabbe's obstetrical textbook, 1993 (1)
Obstetrics: Normal & Problem Pregnancies

American College of Obstetrics & Gynecology (2)
Antepartum & Intrapartum Management June 8-10, 1995

Obstetrical Myths Versus Research Realities (3)
by Henci Goer

Long-Term Fetal Heart Tone Variability ("reassuring patterns") by Auscultation

During active labor, the wellbeing of the unborn baby can be guarded by monitoring the baby's heart tones. "Monitoring" is a verb or activity which can be accomplished in two ways -- either by auscultation (listening to fetal heart tones with a stethoscope or doptone) or with continuous electronic fetal monitoring (EFM). Both are effective and each has its own specific advantages and disadvantages, depending on the circumstances and risk-level of the mother's pregnancy.

According to the peer-review literature, the only identified advantage of continuous Electronic Fetal Monitoring over routine auscultation in low and moderate risk pregnancies is the ability assure fetal wellbeing in the presence of "reassuring" FHT patterns. (1,2,3) The element of "reassurance" comes from discerning the presence of long and short-term beat-to-beat variability. There is no clinically significant difference in fetal well-being between long and short-term variability. Short-term variability can only be discerned by the use of electronic methods. Long-term variability can be discerned through auscultation with the use of the method described below. (1)

The goal of this study design is to detect FHT variability and, when possible, periodic changes associated with uterine contractions (accelerations, early, late & variable decels) through auscultation. Since auscultative monitoring requires the mother to remain immobile during strong uterine contractions (UC) in order for good FHT data to be obtained, it is not always possible to discern periodic changes using this method. However, documenting the presence of good long-term (or cyclic) variability is the basic purpose of the following method. An amplitude of 6 beats per minute (bpm) indicates fetal wellbeing. An amplitude of 2 or less is indicative of a compromised fetus.

The primary purpose of beat-to-beat auscultation in 5 second intervals is to be able to document these "reassuring" FHT patterns without dependence on continuous electronic monitoring. This permits the caregiver more latitude in management and the avoidance of unnecessary intervention (e.g. episiotomy to hasten 2nd stage) as well as added confidence for domiciliary practitioners in the decision to remain at home for the birth and to facilitate as well-timed transfer when warranted.

Research Goals:

To create a repeatable protocol for prospective studies comparing intermittent auscultation by midwives to continuous electronic monitoring of the fetal heart rate.

To document long-term fetal heart rate variability as well as periodic changes in a domiciliary settings (or other "low-tech" circumstances), without the expense and risks associated with the use of continuous electronic fetal monitoring. This has global application as many less affluent populations do not have access to continuous electronic fetal monitoring, especially in the rural areas.

Limitations: Loss of FHT signal due to equipment limitations or maternal movement.

Maternal Cooperation:
Mothers need to be in a stable position that permits the attendant to listen for one full minute. Ideally, a good proportion of these monitoring events should include listening during and following a UC, -- not always easy during the strong painful contractions of transition labor and pushing stage.

Necessary Equipment: either
Doppler or fetascope, a large clock with sweep second hand operated by quartz movement so that the second hand stops momentarily with each "tick", a specific FHT variability graphic form (developed & provided by the author) to record the amplitude of variability of FHTs, calculated in 5 second increments for 12 units ( one minute following UC). To avoid dilution or pollution of data, the highest & lowest numbers during a 60-second set should be heard two or more times during the set OR heard in 2 or more consecutive sets. For instance, a single high or low may be an artifact of counting; inclusion of random artifacts may reduce the clinical value of the system and should be avoided.

Design of Graphic Long-Term Variability Form:
The form quantifies, qualifies and co-ordinates the recording of FHT variability, uterine forces, periodic changes and cervical effacement and dilatation, descent of presenting part (station) and explusive stage (urges to push). In the presence of consistently good variability, simple charting of that information on the labor notes/flow sheet is sufficient. In the absence of fetal heart rate variability or when a specific concern occurs in which it is clinically beneficial to document the relationship of fetal cardiac patterns to uterine activity, this formalized display of data is helpful.

Unlike the real time print-outs of EFMs which results in reams of dis-associated data, this LTV graph has the
advantage of integrating data over many hours of time on a single sheet of paper so that meta-patterns can be discerned, allowing the practitioner to compare fetal heart activity at different stages of labor or under different circumstances. This appears to be a distinct advantage over the current methods of EFM.

Long-term Variability (LTV) is defined as

normal when over 6> bpm amplitude; "reassuring pattern" -- represents a normally oxygenated fetus without evidence of asphxial distress

2) decreased when less than <6 bpm -- may indicate
sleep cycle or CNS depression to drugs or mild to moderate hypoxia

3) absent when less than <2 bpm --
insufficient oxygen to preserve cerebral & myocardial tissue and represents uncompensated fetal acidosis

4) saltatory patterns --
when over 25> bpm -- may indicate a brief or acute hypoxic event.

Periodic Changes: This data is collected during UCs. The type or category noted as -- Accelerations (A), Early (E), Late (L) and Variables (V) decelerations.

Early decels, the lowest point coincides with the peck of the UC in the shape of an inverted bell curve. Late decels begin to dip as the contraction wanes and become most profound after the contraction has ceased. Recent ACOG literature is now grouping both early and late decels together and using the terms "reflex" and "non-reflex", based on the presence or absence of variability to distinguish the clinical importance of this type of pattern. It is considered a "reflex" late decels pattern when the drop in bpm is gradual and mirrors the UC (either during or following the UC) but still maintains long & short-term variability. It is considered to be a true "late" decels when variability is absent. For purposes of this study, I have chosen to maintain the distinction between decels that occur during the UC (early) and those that follow the UC (late).

Variable decels are "V" shaped, in which the fall in FHTs occurs and recovers suddenly. It is the most frequent type of "non-reassuring" pattern. They are variable in duration, shape and profundity from contraction to contraction and thought to be caused by a vagal nerve response. In first stage they are associated with umbilical cord compression; in second stage it is often caused by head compression. As long as variability is present, they are considered to be benign.

The highest or lowest acceleration or decels (as calculated by the lowest or highest 5-second unit) and the length of the period are also noted. For example, if a deceleration occurred during a UC in which the lowest 5 second unit was 8 beats per 5 second for three sets (15 seconds^), it would be charted as: E/96 bpm /15^.

Uterine Forces are quantified on a 1 - 5 scale as follows: Uterine Contractions -- #1) under 30 seconds; #2) 35" to 50"; #3) 55" to 65"; #4) 70" to 85"; and #5) over 90". These time frames are arrived at by palpating the length of the UC manually for the first three UC on the hour (or half-hour).
The author cautions against calculating the length and strength of UCs by asking the mother to tell you when they start and stop or the timing of verbal clues (independent of manual confirmation), as it is often misleading, giving the false impression of a good labor pattern when, in fact, the UCs are of much less intensity and duration.

A second quality of uterine forces is ability to indent the uterine wall during the apex of the contraction.
As UCs increase in length they also increase in strength so that the uterine wall becomes "board-like" or unable to be indented by palpation. In UC of a 1+ or 2+, indentability is normally present. In UC of 3+ or more, it is usually not possible to indent the uterine wall. In instances in which the length of the contraction is great but the quality is poor, subtract 1 or more from the scale. For instance, a UC lasting 60 seconds but never becoming board-like would be charted as a 2+ instead of a 3+ and marked with an asterisk*.

Cervical changes, fetal decent and expulsion are noted traditionally (cx dilation 1-10 cms, effacement in percentages, descent in station -5 through +5). An additional notation of Urges to Push (UTP) is qualified in as: Variable/intermittent (V) Spontaneous/sustained (S) Irresistible/uncontrollable (I). The perineal stage (or incremental crowning) may be indicate by the initial "P".

Intra-uterine resuscitation by instructing the mother NOT to push, anti-gravity positions, lying left side, etc., should be noted here. Administration of maternal 02 due to fetal bradycardia should also be noted on the FHT graph.

Methodology for Intermittent Auscultative Monitoring of Long-Term FHT Variability documenting the presence (or absence) of "reassuring patterns" of fetal wellbeing:

BACKGROUND: "It was soon appreciated that the fetal heart rate counted over a period of time and expressed as a mean (e.g. 150 bpm averaged over 4 to 5 minutes) was an inadequate measurement. Seasoned clinicians, using stethoscopically-derived fetal heart rate data, were wrong at least one-third of the time..." (1) [note: They were correct 2/3 of the time]

Accordingly, investigators began to plot by hand fetal heart rate in a beat-by-beat manner. Subsequently, an electronic system, the current fetal heart rate monitor, was developed to do this function automatically." "...heart rate auscultated by the human ear must be averaged over a given number of beats in seconds or minutes, and this averaging destroys the physiologic detail." [Gabbe's obstetrical textbook p.461]

To correct for the problem of averaging which "destroys physiological detail", the following methodology has been developed:

Use a large battery powered clock (7" or larger), with a quartz movement so that the sweep second hand stops momentarily with each "tick".
If possible, listen for a full 60+ seconds and chart the range (typically ranging between 10 to 14 bp5s^. The form allows for a broad range from 5 bp5s^ to 15 bp5s^, providing for tracking of a baseline range from 60 bpm to 192 bpm. The line for 12 bp5s^ (144 bpm) is blackened to assist reading the graphic for the normal physiological baseline. Also the lines indicating 120 bpm/10 bp5s and 156 bpm (13 bp5s) are lightly shaded in blue to establish the normal range of fetal variability.

Time protocols for long-term variability via auscultation:

Active labor, defined as UC q 5' x 60"(3+) for one hour or longer : listen every 30 minutes for one full minute, preferably during and immediately following a UC.

Because it is necessary for the mother to be immobile, it is sometimes difficult to use this method during a UC. Typically, heart tones of a fetus with normal variability will `wander' between 10 - 13. For example 12, 12, 11, 10, 10, 11, 12, 10, 10, 13, 12, etc.
According to outcome studies, good variability is still the best predictor of fetal well-being. Lack of variability is quite distinct, as the number (for example, baseline of 120 bpm or 10 bp5s^) will be incredibility precise and predictable, giving rise to a mechanical quality of repetition. As in the above example, the 10th beat will occur again and again and again at precisely the last "tick" of the 5^ unit for 12-18 times in a row without any variation. If this mechanical quality is heard, listen every 5 minutes. If present more than 10 minutes the practitioner may choose to stimulate the fetus through the "earthshake" maneuver (slow external shaking or jostling abdominal wall) or vaginally rubbing the baby's scalp. If that doesn't resolve the problem, consider transfer to medical management unless delivery is imminent.

Second stage is defined as spontaneous sustained pushing (Sustained Urges To Push or SUTP) after full dilatation.
Listen every 10 minutes, with additional monitoring at 5-second intervals between times as indicated. It is not uncommon for a period of early decels, down to 1/2 of the baseline, to occur as the baby's biparietals are first pushed down into contact with the mother's ischial spines, causing head compression and triggering a vagal reflex. For instance, a fetal baseline of 140 may go down 70 at the peak of the UC. This phenomenon is usually short-lived (<< 10 minutes) and the baby continues to display variability, good recovery and return to baseline. I have also seen this occur with a tight nucal cord or occult cord prolapse of a non-lethal nature.

Copyright @ 1995 --
reprint with author's permission only

Useful Information/Quotes from Gabbe's Obstetrical Textbook
Obstetrics: Normal and Problem Pregnancies

Perhaps the most reliable indicator of fetal well-being available to the obstetrician is the finding of normal beat-to-beat variability."

"It is unusual for a heart rate under normal nervous system control to be steady at any one consistent rate.
Rather, there is considerable variation or short-term variability on a beat-to-beat basis, usually ranging from 3 to 8 bpm around an imaginary average heart rate. Fluctuation or long-term variability occurs as well, usually having a cyclicity of three to five cycles per minute (cpm). The presence of normal fetal heart rate variability is one of the best indicators of intact integration between the central nervous system and the heart of the fetus."

"The clinical significance of short-term variability or beat-to-beat variability has been assessed for a number of years. To date,
no clinical significant difference between long-term and short-term variability is uniformly apparent or clinically significant. Wherever there is good beat-to-beat variability present on a heart rate tracing without other indicators of loss of fetal well-being, the likelihood of delivering a significantly-jeopardized fetus is exceedingly low. Even when other parameters suggest fetal distress, the presence of good beat-to-beat variability is generally a reassuring finding." [26]

"Exaggerated or increased fetal heart rate variability ( >>25 bpm) may be representative of a shifting PO2 and PCO2 relationship..."p.466

Periodic Changes -- "Transient slowing of the fetal heart rate with UC is known as a deceleration, while a transient increase is known as an acceleration. The four patterns of clinical significance are accelerations and early, variable and late decelerations." p. 469

"It was soon appreciated that the fetal heart rate counted over a period of time and expressed as a mean (e.g. 150 bpm averaged over 4 to 5 minutes) was an inadequate measurement. Seasoned clinicians, using stethoscopically derived fetal heart rate data, were wrong at least one-third of the time..." (NOTE: They were correct 2/3 of the time)

Accordingly, investigators began to plot by hand fetal heart rate in a beat-by-beat manner. Subsequently, an electronic system, the current fetal heart rate monitor, was developed to do this function automatically." "...heart rate auscultated by the human ear must be averaged over a given number of beats in seconds or minutes, and this averaging destroys the physiologic detail." p. 461 [emphasis added]

"Fetal heart rate variability can only be appreciated when it is continuously and instantaneously calculated and recorded on a beat-by-beat basis."

However, in prospective, randomized studies, the incidence of neurologic damage and perinatal death associated with the use of electronic fetal monitoring is not significantly lower than documented with older methods of fetal surveillance, including intermittent fetal rate auscultation by stethoscope or Doppler." p. 457

...has been demonstrated that electronic fetal heart rate monitoring is associated with an increased incidence of delivery by cesarean section without demonstrable improvement in perinatal outcome..." p. 457

"...the outstanding value of fetal heart rate monitoring during the intrapartum period is the reasonable sensitive ability of the technique to confirm fetal well-being and to permit labor to continue without unnecessary intervention.
Unfortunately, this method of surveillance is less able to identify if the fetus is clearly in distress. Accordingly, in utilizing fetal heart rate monitoring alone, a large number of fetuses that are in good condition and that show no clinical evidence of morbidity may be delivered by "emergency" measures." p. 484

"Most of the criticism of EFM has been aroused by this deficiency. Banta and Thacker [47] reviewed
the world literature and could find no statistical evidence that fetal heart rate surveillance reduced perinatal morbidity or mortality. p. 484

A few large prospective investigations have recently failed to demonstrate that continuous EFM is associated with an improved outcome." "In total, 16, or almost 80% of the 22 cases of cerebral palsy had not shown clinical evidence suggestive of intrapartal asphyxia. The incidence of cerebral palsy was nearly identical for both groups, 1.8:1,000 for EFM and 1.5:1,000 for the intermittent auscultation. The authors concluded that, compared with intermittent auscultation, EFM had little if any, protective effect against cerebral palsy. Overall, it appears that no more than 20% of cases of CP are associated with intrapartal events." [54] "Recent studies have also failed to demonstrate improved outcomes in pre-term infants followed with continuous EFM as compared with periodic auscultation." [55]

It is the opinion of ACOG, as reported in its technical bulletins [59,60], that continuous EFM with acid-base support and appropriate intermittent monitoring by auscultation or Doppler ultrasound are of equal value for the monitoring of the fetus. Some investigators have emphasized that, on a statistical basis, there is little advantage to continuous EFM for the normal fetus." "It must be emphasized that in most studies comparing EFM to auscultation, auscultation has been carried out by a single nurse at the bedside. Such staffing is not possible in most institutions. [61] p.485 (emphasis added)

[Note: midwifery care naturally provides this auscultative model of one-on-one care at the mother's side]

Informed Refusal Protocol according to Gabbe's Textbook

An occasional patient simply refuses any form of fetal surveillance. When appropriate explanations have been given and the patient still declines the process, it is generally advisable to have two independent observers document in the chart that the patient refuses "usual and customary forms of intrapartum fetal surveillance" in order to establish the facts that (1) the surveillance was offered, (2) the reasons for its use were explained, and (3) the complications that can arise from not using these forms of monitoring were known to the patient and fully understood at the time of the refusal." p. 489

ACOG Antepartum & Intrapartum Management June 8-10, 1995

Material published by the 1995 ACOG conference states that:
"Fetal Heart Rate Monitoring was introduced into clinical practice ... without trials of its effectiveness and now trials are unable to show efficacy in clinical usage." "Despite lack of efficacy, FHRM is widely used in North America, with no apparent decrease in usage since publications of its lack of efficacy. This extensive usage continues despite possible deleterious effects (e.g., increased cesarean section rate) [p. 157] "In several randomized trials ... there is no evidence of any meaningful decrease in asphyxial damage in babies who were continually monitored. There is a significant increase in cesarean sections in monitored cases." [p. 159] In regard to reducing cerebral palsy through obstetrical management, it notes that: "...there is no evidence for the widespread belief that intrapartum care commonly influences the risk of cerebral palsy..." "... the vast majority of cases of cerebral palsy are exceedingly unlikely to be preventable by more intensive forms of intrapartum care". [p. 152, ]

Statistical data from
Myths Versus Research Realities
by Henci Goer:

Mortality rates for Women of childbearing age per 100,000 -- a comparison of vaginal birth, cesarean section and auto accidents

Vaginal Birth:
6 deaths per 100,000 // or ratio 1 death out of 16,666 deliveries

Auto Accidents women ages 14-40:
20 deaths per 100,000 // or ratio of 1 death for
every 5,000 women in that age bracket

Cesarean Section:
31 per 100,000 // or ratio of 1 death out of 3225 surgeries

Electronic Fetal monitoring is directly associated with an increase in cesarean surgeries
without any decrease in either fetal mortality or cerebral palsy. Cesarean surgeries are directly associated with increased rates of maternal mortality.

Preventing unnecessary cesarean surgeries prevents maternal mortality. Replacing EFM with auscultation prevents maternal deaths and spares both mother and baby the interruption of bonding that accompanies cesarean surgery. Prevention of medically-unnecessary reproductive surgeries increases opportunities for valuable maternal-child interaction during the postpartum, promotes family values and the rate of successful breastfeeding and reduces the cost of maternity care. It should become the standard of care except in circumstances of evident medical need.