Journal of Midwifery & Women’s Health
www.jmwh.org
Commentary
Management of Labor: Are the New Guidelines Justified? Wayne R. Cohen, MD, Melanie Sumersille, CNM, MSN, Emanuel A. Friedman, MD, MedScD
INTRODUCTION
The character of birthing practice shifts periodically in response to evolving social and medical mores and values, the popularity of new technology, novel research findings, and published guidelines. In recent years, much attention has been focused on the rising cesarean rate. Fully a third of pregnant women in the United States have a cesarean birth; in some locales, the rate is substantially higher. Today’s average parturient weighs more, is older, carries a larger fetus, and is more likely to use epidural anesthesia than in the past. Nevertheless, these factors explain only a small portion of the rising cesarean rate. There is also a trend toward fewer trials of labor in women with a prior cesarean. Consequently, reducing the cesarean rate will require a reduction in primary cesareans. The most substantial contributor to the rise in the primary cesarean rate is more cesareans being done for dystocia than ever before. Pervasive concerns about the diagnosis of dystocia and its effect on the cesarean rate have led to renewed interest in identifying and managing abnormal labor progress.1–3 New guidelines have been issued by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine,4 and embraced by the American College of NurseMidwives and the Association of Women’s Health, Obstetric and Neonatal Nurses.5,6 These new guidelines are the focus of this commentary. DEFINING ABNORMAL LABOR PROGRESS
Diagnosing dystocia—defined inclusively as abnormal labor progress—requires a clear grasp of when progress is within the broad range of normal (and therefore unlikely to require intervention) and when a woman’s labor progress is not normal. This is particularly important to midwives and intrapartum nurses, who are the providers often charged with first identifying dysfunctional labor and suggesting requisite interventions. Current understanding of labor progression derives primarily from the seminal work of Emanuel Friedman. Dr. Friedman’s observations, beginning in the 1950s, clarified the relationships among cervical dilatation, fetal station, and elapsed time in labor. This analysis led to defining the range of normal for various phases and stages of labor so they could be applied in a template for logical and consistent clinical decision making.7–9 Friedman’s approach added a measure of uniformity and measurement objectivity to a process that had been previously ruled by the experience-based and subjective notions of
physicians and midwives. The process of assessing and managing labor progress over time was verified, adopted, and modified by many others,10–18 and has formed the basis for identifying dysfunctional labor in a wide range of populations for more than a half-century. This kind of system has proved to be a valuable clinical tool for those who have taken the time to master its nuances and complexities. Using it exposes some of the dynamic beauty and logic of the normal birth process and provides an efficient and accurate means to identify when that process has faltered. Recently, obstetric, midwifery, and nursing leaderships have adopted new concepts about progression of cervical dilatation and fetal descent.19,20 It is regrettable that in the rush to adopt the new recommendations our specialties ignored a fundamental principle: before endorsing new clinical strategies, wait to prove them equivalent or superior to existing approaches with regard to both benefits and risks. WHY ADOPT NEW GUIDELINES?
Why the apparent hunger to adopt these untested guidelines? Our haste has been fed in part by the perceived urgency to dampen or reverse the rising cesarean rate, coupled with the specious notion that the Friedman system of labor assessment has not served us well. The forces driving the cesarean rate are multiple and complex and, like most complex problems, defy easy understanding and facile solutions. While we agree the rate is unconscionably high, we worry that strategies directed primarily at moderating the cesarean rate may be too simplistic and ultimately counterproductive. Our goal should not be only to avoid operative birth, however laudable it is to diminish the incidence of unnecessary cesareans; it is rather to provide care that results in a safe birth. Guidelines grounded in the latter perspective will serve women and newborns optimally; those designed principally to reduce the cesarean rate without ensuring maternal and fetal safety will not. High cesarean rates are a manifestation of a more pervasive problem. Treating symptoms seldom resolves underlying disease. If we apply decision making geared to good outcomes (ie, avoiding harm and unneeded intervention), optimal cesarean rates will reveal themselves. MISCONCEPTIONS ABOUT THE FRIEDMAN SYSTEM OF LABOR ASSESSMENT
Address correspondence to Wayne R. Cohen, MD, 4841 North Valley View Road, Tucson, AZ 85718. E-mail:
[email protected]
Criticisms abound about the Friedman system of labor assessment and management, including lack of corroboration by others; inapplicability to contemporary practice; unnecessary management rigidity that ignores the intrinsic variation in labor; using labor curves is unnecessary and increases the cesarean rate. None of these proves true if the curves are used
1526-9523/09/$36.00 doi:10.1111/jmwh.12712
c 2018 by the American College of Nurse-Midwives
1
in concert with the many logic- and evidence-based management principles derived from them.8,9 Numerous studies conducted over several decades have confirmed the basic nature of the original curves and validated their clinical utility.10–18 Findings from diverse populations have been remarkably consistent, nearly all authenticating Friedman’s observations. This corroboration in many different settings supports the generalizability of this system. The Friedman system acknowledges the great variation in normal labor patterns and provides an objective means to identify abnormalities. The introduction of graphic labor assessment occurred at a time when cesarean birth rates were far lower than exist today. There were higher rates of instrumental birth and different analgesic agents and techniques, all of which could potentially affect labor progress. Nevertheless, Friedman evaluated labor progress in women who experienced various interventions as well as in women who had no medical intervention. Moreover, the specific effects of various maternal and fetal influences on labor progress (eg, fetal weight, position and presentation, maternal age and weight, epidural anesthesia and systemic opioid analgesia) were meticulously documented.8 The use of labor curves has been associated with a reduction in the cesarean birth rate12 and perinatal mortality.14 Perhaps most importantly, the curves foster answering questions about both short-term prognosis (eg, what is the likelihood of safe vaginal birth?) and long-term prognosis (eg, what is the likelihood of compromised neurologic development?) that could not otherwise be addressed.8,21 Many midwives will applaud the new guidelines, because at first glance they may seem more consonant with midwiferystyled approaches to the evaluation of labor, which tend to allow women more time in labor than conventional medical models. On closer inspection, however, the new guidelines encourage practices that could cause harm. For example, allowing a 4-hour second stage using the Friedman system, as long as progress in descent was continuous, the pelvic architecture accommodating, and the fetus well-oxygenated, would be reasonable. By contrast, allowing a 4-hour second stage with no change in fetal station in a small, narrow pelvis, which is consistent with the new guidelines, would be futile and potentially harmful.
clinical observations, they used a curve-fitting program to analyze a multi-institutional database retrospectively. Their approach incorporated selection biases and unadjusted confounders that likely distorted their results. These shortcomings were in fact acknowledged by Zhang et al.26 Nonetheless, in the enthusiastic embrace of the new labor curves scant attention has been paid to those admissions. Further, they excluded women who gave birth by cesarean and those whose cervix was more than 6 centimeters dilated at admission. Slow labor had occurred in many in the deleted cesarean group, thus falsely increasing the average dilation rate in the remaining study cases. Omitting the late admission cases likely excluded many very rapid labors, contributing to the overall appearance of slow average dilation. These and other problems indicate the new guidelines were built on an unsound foundation. Moreover, they ignored the potentially adverse effects of abnormal labor on maternal and newborn well-being.21,27–30
THE NEW LABOR CURVES
Diagnosis of Arrest of Dilatation
Given the extensive investigative work and vast clinical experience based on the traditional labor curves, it is disingenuous to assume they are incorrect. The original labor curves were based on direct observations, that is, uniform and frequent clinical examination of women during labor. Their nature was confirmed by real-time mechanical, electronic, and ultrasonographic cervimetry.22,23 The new labor evaluation guidelines rely on statistical methods used by Zhang et al to describe labor patterns based on previously collected data.19,20 Why do their labor curves diverge from those of nearly all past observers? Differences have more to do with case selection and analytic methods than with any real difference in how labor progresses. Our concerns about the approach used by Zhang et al have been detailed elsewhere.24,25 Rather than using direct
To diagnose arrest of dilatation the new guidelines require the cervix be at least 6 centimeters dilated, the membranes ruptured, and no progression for 4 hours or more with adequate contractions, or at least 6 hours with inadequate contractions augmented by oxytocin. Adequate uterine contractility is defined as “eg, more than 200 Montevideo Units,” implying that an intrauterine pressure transducer (IUPT) is necessary to diagnose an arrest of dilatation. However, studies have shown convincingly that the use of IUPTs has no advantage when compared to noninvasive means of assessing contractility.33 IUPT readings do not correlate well with progress in cervical dilatation or with cesarean rates. Normal progress in dilatation is achieved over a broad range of uterine activity. Widespread use of IUPTs would increase costs, and more patients would incur the risks of artificial rupture of membranes.
2
Transition to Active Phase
The new guidelines indicate that the transition from latent to active phase occurs at a dilatation of 6 centimeters. It is widely assumed that in the Friedman dilatation curve active phase begins at 4 centimeters. This is a puzzling and erroneous simplification. In fact, the Friedman system categorically discourages using any specific degree of dilatation for diagnosis of active phase labor.8,9 Active phase usually begins at 3 to 6 centimeters of dilatation and, not infrequently, earlier or later.31 Correct identification of the transition can be accomplished only by real-time interpretation of serial clinical examinations for any given patient. When graphed against time, the resulting curve can be seen to change from the slowly evolving latent phase to the more rapidly progressing active phase. It is the upward inflection of the dilatation curve, regardless of the specific dilatation at which it occurs, that marks the beginning of the active phase of the first stage of labor. Under the new guidelines, important abnormalities (such as protracted active phase and arrest of dilatation) that are recognized in the Friedman system before 6 centimeters of dilatation would be considered normal. Failure to diagnose them could expose fetus and gravida to risk.21,27–30,32
Volume 0, No. 0, xxxx 2018
The proposed definition would allow, for example, a woman who has strong contractions with labor arrested at 8 centimeters to continue for at least 4 hours, plus an additional 4 hours if the membranes were not ruptured until after the first 4 hours. This means a woman with strong contractions could remain at 8 centimeters of dilatation for 8 hours before she would meet the criteria for an arrest of dilatation. The guidelines fail to consider whether there were preceding labor abnormalities, evidence of cephalopelvic disproportion, infection, and other factors that might be contributing to the dysfunction and could enhance risk from delayed birth. As important, the recommendations implicitly deny the possibility that the fetus could be put at risk by prolonged exposure to strong contractions in a birth canal of insufficient capacity.21,27–31 The Second Stage
The new guidelines define second-stage limits by hours elapsed after full cervical dilatation. They indicate that an “arrest of labor in the second stage” can be diagnosed only after a nullipara has been pushing for at least 3 hours and a multipara for 2 hours. This approach is unsophisticated and insensitive compared to assessing the rate of fetal descent. Using only the clock makes it impossible to distinguish among protracted, arrested, and failed descent, each of which confers a different prognosis for the labor ending in a vaginal birth.8,9 Moreover, morbidity associated with a very long second stage occurs primarily in those with abnormal descent patterns, indicating the approach recommended by the guidelines will result in more maternal and neonatal morbidity.34 Most studies of second-stage length found little effect of duration per se on early neonatal outcome for second stages up to about 3 hours, although maternal morbidity from infection and hemorrhage tend to rise before that time.35 A second stage longer than 3 hours, as promulgated by the guidelines, is potentially more likely to be associated with morbidity.30,35 Unfortunately, few studies of the impact of second-stage duration have stratified cases by rates of descent. Furthermore, little information exists about long-term neonatal or maternal morbidity. The likely consequence of the very long second stages promoted by the guidelines, especially in the absence of descent, will be maternal and fetal harm. Without more information about the effects of such labors on the maternal pelvic floor or on the fetus exposed repetitively to intracranial pressures sufficient to impair brain blood flow,32 it seems premature and imprudent to adopt the new recommendations.
pelvis, all of which can be determined accurately by a trained clinician. The response to oxytocin, the fetal heart rate pattern, fetal weight and sex, maternal body mass, and the presence of infection are all important in this regard. Apropos, the new guidelines have arisen at a regrettable time when our educational systems have deemphasized the importance of understanding basic principles of the mechanism of labor and meaningful intrapartum physical examination as vital skills. We dare not be complacent about the long-term risks of dysfunctional labor that is not treated promptly. We don’t know nearly enough about the association of long labor with chorioamnionitis, neonatal ischemic encephalopathy, birth injury, and permanent maternal pelvic floor damage. These substantial knowledge gaps make us concerned about the uncritical adoption of guidelines for the assessment of labor that have a deficient evidence base. Several lines of evidence support the notion that dysfunctional labor per se (ie, even without evidence of fetal oxygen deprivation) can cause brain injury, and that some of this type of damage is not apparent in the immediate neonatal period.21,27–30,36–39 If followed, the new guidelines may (or may not) reduce the cesarean rate, but at what cost? We urge that their risks and benefits be studied thoroughly—by means of a large randomized controlled study, at minimum—to compare them with traditional approaches before introducing them into practice. Further, we need to reemphasize basic clinical skills (such as determination of presentation, position, station and dilatation, cephalopelvimetry, etc,) into midwifery and obstetric training and to study other variables that have influenced the unfettered growth of cesarean birth. AUTHORS
Wayne R. Cohen, MD, is Clinical Professor of Obstetrics and Gynecology at the University of Arizona College of Medicine in Tucson. He is coauthor with Emanuel Friedman of Labor and Delivery Care: A Practical Guide. Melanie Sumersille, CNM, MSN, FACNM, is a fellow of the American College of Nurse Midwives and a member of its Reducing Primary Cesarean Collaborative. She is in private practice in Garden City, NY. Emanuel A. Friedman, MD, MedScD, is Professor Emeritus of Obstetrics, Gynecology and Reproductive Biology at Harvard Medical School. CONFLICTS OF INTEREST
The authors have no conflict of interest to disclose. REFERENCES
APPLICATION
The assessment of labor is a process of serially estimating the likelihood of a safe vaginal birth.9 Evaluation of labor graphs should be part of that estimation, but they must be interpreted in the clinical context. A dysfunctional dilatation or descent pattern provides valuable prognostic information, but other factors contribute to the probability of safe or hazardous birth. These include the degree of fetal cranial molding, position and attitude of the presenting part, and the architecture of the Journal of Midwifery & Women’s Health r www.jmwh.org
1.Millen KR, Kuo K, Zhao L, Gecsi K. Evidence-based guidelines in labor management. Obstet Gynecol Surv. 2014;69(4):209-217. 2.Cahill AG, Tuuli MG. Labor in 2013: the new frontier. Am J Obstet Gynecol. 2013;209(6):531-534. 3.Spong CY, Berghella V, Wenstrom KD, Mercer BM, Saade GR. Preventing the first cesarean delivery: summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, and American College of Obstetricians and Gynecologists Workshop. Obstet Gynecol. 2012;120(5):1181-1193.
3
4.Obstetric Care Consensus Number 1. Safe prevention of the primary cesarean delivery. Obstetric Care Consensus No. 1. American College of Obstetricians and Gynecologists. Obstet Gynecol. 2014;123(3): 693-711. 5.Evidence-Based Practice: Pearls of Midwifery. Silver Spring, MD; 2014. Available at Midwife.org. Accessed May 3, 2017. 6.Stephens-Hennessy BM. Is six the new four: assessing, defining and promoting progress in labor. AWHONN Webinar, December 11, 2015. 7.Cohen WR, Friedman EA. The assessment of labor: a brief history. J Perinat Med. 2017; Mar 22. pii: /j/jpme.ahead-of-print/jpm-20170018/jpm-2017-0018.xml. https://doi.org/10.1515/jpm-2017-0018. [Epub ahead of print] 8.Friedman EA. Labor: Clinical Evaluation and Management. 2nd ed. New York, NY: Appleton-Century-Crofts; 1978. 9.Cohen WR, Friedman EA. Labor and Delivery Care: A Practical Guide. Oxford, England: John Wiley & Sons, Ltd; 2011. 10.Bottoms SF, Hirsch VJ, Sokol RJ. Medical management of arrest disorders of labor: a current overview. Am J Obstet Gynecol. 1987;156(4):935-939. 11.Kwast BE, Lennox CE, Farley TMM. World Health Organization partograph in management of labour. Lancet. 1994;343(8910):13991404. 12.Studd J, Clegg DR, Sanders RR, Hughes AO. Identification of high risk labours by labour nomogram. Br Med J. 1975;2(5970):545547. 13.Van Bogaert LJ. The partogram’s result and neonatal outcome. J Obstet Gynaecol. 2006;26(4):321-324. 14.Drouin P, Nkounawa F. The value of the partogramme in the management of labor. Obstet Gynecol. 1979;53(6):741-745. 15.Lekprasert V. Monitoring of labour by graph. J Med Assoc Thai. 1972;55(11):647-653. 16.Philpott RH, Castle WM. Cervicographs in the management of labour in primigravidae. II. The action line and treatment of abnormal labour. J Obstet Gynaecol Br Commonw. 1972;79(7):599-602. 17.Melmed H, Evans M. Predictive value of cervical dilatation rates. I. Primipara labor. Obstet Gynecol. 1976;47(5):511-515. 18.Ledger WJ, Witting WC. The use of a cervical dilatation graph in the management of primigravidae in labour. J Obstet Gynecol Br Commonw. 1972;79(8):710-714. 19.Zhang J, Troendle JF, Yancey MK. Reassessing the labor curve in nulliparous women. Am J Obstet Gynecol. 2002;187(4):824-828. 20.Zhang J, Troendle J, Mikolajczyk R. Sundaram R, Beaver J, Fraser W. The natural history of the normal first stage of labor. Obstet Gynecol. 2010;115 (4):705-710. 21.Friedman EA, Neff, RK. Labor and Delivery: Impact on Offspring. Littleton, MA: PSG Publishing; 1987. 22.Kok FT, Wallenburg HCS, Wladimiroff JW. Ultrasonic measurement of cervical dilatation during labor. Am J Obstet Gynecol. 1976;126(2):288-290.
4
23.Friedman EA, Von Micsky LI. Electronic cervimeter: A research instrument for the study of cervical dilatation in labor. Am J Obstet Gynecol. 1963;87:789-793. 24.Cohen WR, Friedman EA. Perils of the new labor management guidelines. Am J Obstet Gynecol. 2015;212(4):420-427. 25.Cohen WR, Friedman EA. Viewpoint: misguided guidelines for managing labor. Am J Obstet Gynecol. 2015;212(6):753-754. 26.Vahratian A, Troendle JF, Seiga-Riz AM, Zhang J. Methodological challenges in studying labour progression in contemporary practice. Pediatr Perinat Epidemiol. 2006;20(1):72-78. 27.Towner D, Castro MA, Eby-Wilkens E, Gilbert WM. Effect of mode of delivery in nulliparous women on neonatal intracranial injury. N Engl J Med. 1990;341(23):1709-1714. 28.Friedman EA, Sachtleben MR, Bresky PA. Dysfunctional labor XII. Long-term effects on infant. Am J Obstet Gynecol. 1977;127(7):779783. 29.Friedman EA, Sachtleben-Murray M, Dahrouge D, Neff RK. Longterm effects of labor and delivery on offspring: a matched-pair analysis. Am J Obstet Gynecol. 1984;150(8):941-945. 30.Leveno KJ, Nelson DB, McIntire DD. Second-stage labor: how long is too long? Am J Obstet Gynecol. 2016;214(4):484-489. 31.Peisner DB, Rosen MB. Transition from latent to active labor. Obstet Gynecol. 1986:68(4):448-451. 32.Schifrin BS, Deymier P, Cohen WR. Fetal neurological injury related to mechanical forces of labor and delivery. In: Zhang L, Longo L, eds. Stress and Developmental Programming in Health and Disease: Beyond Phenomenology. New York, NY: Nova Biomedical; 2014:651688. 33.Bakker JJ, Verhoeven CJ, Janssen PF, van Lith JM, van Oudgaarden ED, Bloemenkamp KW, et al. Outcomes after internal versus external tocodynamometry for monitoring labor. N Engl J Med. 2010;362(4):306-313. 34.Cohen, WR, Mahon T, Chazotte C. Very long second stage of labor: characteristics and outcome. In: Cosmi EV, ed. Labor and Delivery: The Proceedings of the Second World Congress on Labor and Delivery. New York, NY: Parthenon Publishing Group; 1998:348-351. 35.Cohen WR. Influence of second stage duration on perinatal outcome and puerperal morbidity. Obstet Gynecol. 1977;49(3):266-269. 36.Laughon SK, Berghella V, Reddy UM, Sundaram R, Lu Z, Hoffman MK. Neonatal and maternal outcomes with prolonged second stage labor. Obstet Gynecol. 2014;124(1):57-67. 37.Cowan F, Rutherford M, Groenendaal F, et al. Origin and timing of brain lesions in term infants with neonatal encephalopathy. Lancet. 2003;361(9359):736-742. 38.Yeh P, Emary K, Impey L. The relationship between umbilical cord arterial pH and serious adverse neonatal outcome: analysis of 51 519 consecutive validated samples. BJOG. 2012;119(7):824-831. 39.Scher MS, Belfar H, Martin J, Painter MJ. Destructive brain lesions of presumed fetal onset: antepartum causes of cerebral palsy. Pediatrics. 1991;88(5):898-906.
Volume 0, No. 0, xxxx 2018
