Introduction
In contemporary maternity care practice it is frequently agreed that normal physiological labor should progress continuously: contractions should gradually increase in their intensity and regularity; the cervix should soften and open up; and the fetal head should descend until the child is born.1,2 Consequently, if at some point during labor the observable processes slow, stall, or pause, this is frequently diagnosed as pathological: a slowing contraction pattern may be diagnosed as "uterine dystocia," stalling descent of the fetal head as "pelvic dystocia," and a pause in cervical effacement as "cervical dystocia," or more generally as a "failure to progress" or "labor arrest."3,4
In contrast to this understanding of pathological plateaus, midwives who are experienced in supporting normal labor, often in out-of-hospital settings, report the occurrence of what they regard as physiological labor plateaus.5,6 One example is the "rest and be thankful phase" or "catch-up break" that is anecdotally reported at the beginning of second stage labor.7,8 These concepts refer to slowing or pausing contractions that resume naturally, presumably after a feto-maternal adaptation has occurred.8 Contrary, in a clinical setting, if contractions slow or pause in second stage, this is commonly understood as pathological and frequently results in the administration of oxytocin to induce strong and rhythmic contractions.4 Another example where a labor plateau might be perceived differently in different settings is a phenomenon sometimes called "pasmo," where a woman's reportedly strong and regular contractions seem to disappear the moment she enters the labor ward from a non-hospital setting.9 The term "pasmo" frames this phenomenon as a physiological response to the unfamiliar environment, requiring the midwife to do little more than wait until the woman feels safe enough to continue labor.9 In comparison, in a clinical environment, any plateau during established, or active, labor (that is when cervical dilatation reaches 4 cm to 6 cm)10 is usually regarded as pathological. In essence, a plateau during labor may be perceived as either pathological or physiological, depending on the circumstances: what one person regards as pathological might be another person's normal.
Some researchers agree that physiological labor plateaus occur, which is evident in the way they describe physiological labor in general, or plateaus more specifically. For example, Walsh mentions empirical evidence of physiological plateaus in active labor in home birthing women in North America, citing an unpublished study by Daviss et al.11 Walsh also acknowledges the "rest and be thankful phase" as an example of unorthodox childbirth knowledge.11 Winter et al. describe plateaus as "lulls" that can occur at any time during labor and may be essentially physiological.6 Finally, several researchers challenge the dominant authority of linear labor progression and advocate for a broader definition of what is regarded as "normal" in physiological labor and birth.12-16
The conviction of some that plateaus are a normal, healthy part of labor, raises the question of whether labor plateaus might be incorrectly diagnosed as pathological labor arrest. Of course, for safety reasons, it is essential to identify women who experience truly pathological labor progress in a timely manner and initiate treatment. However, if a woman's normal, physiological labor is mistakenly perceived as pathological, she may be subject to undue interventions that can introduce harm to both mother and child.3,16,17 In the medicalized birth environment of many middle- and high-income societies, when labor is perceived as too slow, women are subject to interventions aimed at expediting labor, even if no other parameter indicates maternal or fetal distress.10,11 Common interventions include administration of oxytocin, artificial rupture of membranes, and directed forceful pushing.18-20 These interventions can have devastating effects including, but not limited to, fetal acidosis, premature separation of the placenta, hemorrhage, extensive damage to maternal perineal tissues, impaired long-term mental health, and fetal or maternal adverse outcomes.21-23 Paradoxically, and despite the associated risks, many of these interventions are reported as unnecessary in retrospect; for example, Swedish studies have found labor augmentation with oxytocic agents to be unjustified in 43% to 66% of cases.24,25 One underlying problem is the application of inconsistent definitions for dystocia.3,25 An exploration of the evidence behind labor plateaus as potentially physiological processes could help in the effort to delineate physiological from pathological labor. This can contribute to reducing unnecessary interventions, and improving maternal and infant health and well-being.
Currently, childbirth researchers and practitioners face particular challenges when exploring the topic of physiological labor plateaus where a shared conceptualization and definition is lacking. As previously mentioned, a variety of terms refer to physiological labor plateaus, including "rest and be thankful phase,"8 "catch-up break,"7 "deceleration phase,"26 "transitional stage,"27 and "latent second stage,"28 amongst others. Childbirth researchers and practitioners could benefit from a shared definition of physiological labor plateaus, ideally with a clear distinction between physiological and pathological phenomena. The proposed mapping review will help to delineate varying concepts of plateaus in normal physiological labor, define their boundaries, serve as basis for further research, and inform practice and practitioner education.
A scoping review is a suitable tool to map concepts and terminology that are applied within a specific context.29 This is particularly useful when the topic is not sufficiently narrow to allow a systematic review of literature, and when evidence has heterogenous formats and qualities.30 For example, an initial cursory search indicates that relevant publications on this topic appear in a variety of formats, including peer-reviewed articles, unpublished theses, conference proceedings, and gray literature.5,8,31 Therefore, the scoping review needs to be inclusive of different types of evidence and of different publication formats. Furthermore, there is currently no agreed umbrella term for different phenomena that may constitute physiological labor plateaus. This proposed scoping review will provide an essential starting point for future theory-building research.
In this scoping review, we will explore concepts and definitions that refer to plateaus within the boundaries of normal physiological labor. The population of interest is women during labor, comprising the time from onset of labor until birth of the placenta. The concept of focus is labor plateaus, defined as a slowing, stalling, or pausing of any observable labor process. This may include but is not limited to the pattern of contractions, cervical effacement, and fetal descent. The context of the scoping review is normal physiological labor and birth. We acknowledge that "normal labor" is an ambiguous term, and further specification is provided in the methods section. Through the proposed strategy, we aim to contribute to a better understanding of normal labor and birth, thereby supporting the collective mandate formulated by the International Confederation of Midwives (ICM) to "keeping birth normal."32
We conducted a preliminary search for existing literature reviews between August and October 2019. The databases MEDLINE and Scopus, the Cochrane Library, and the Centre for Review and Dissemination (CRD) were searched. We identified one literature review that was part of a thesis, but the literature review was largely restricted to publications in German and did not provide an overview of different concepts and definitions.5 Further, we identified publications that qualify for inclusion in this scoping review, but none included a literature review of concepts or terms of physiological plateaus. An overview of existing concepts and terminologies is essential for research in this area, as it can help differentiate concepts and explore the usefulness of an umbrella term for this phenomenon. Based on this planned scoping review it will be possible to design clearly focused research proposals or conduct a concept analysis of this phenomenon.
Review objective
The primary objective of the planned scoping review is to provide an overview of contemporary concepts and definitions that describe plateaus during normal physiological labor and birth. For each identified concept, we aim to establish the concept origin, varying terminology (if applicable), concept boundaries, as well as precedents and consequences of the described phenomenon. Thereby, we aim to conceptualize the boundaries for a future umbrella term for physiological labor plateaus, in preparation for further research.
Inclusion criteria
Inclusion and exclusion criteria for the scoping review are presented following the PCC mnemonic recommended by JBI.30
Participants
Publications that focus on women during labor will be considered for this review. The exact timing of labor onset is contested in childbirth research and practice, resulting in heterogenous definitions of labor.33 As this review aims to provide a comprehensive overview, an inclusive approach to the definition of labor onset will be applied. Therefore, we define labor onset as the earliest point where either the laboring woman or her attending midwife considers that labor has commenced, irrespective of the contraction pattern or cervical effacement at that time. Further, we define the end of labor as the time when the complete placenta and membranes are born.
Concept
The concept of interest includes any phenomenon where the labor process appears to slow, stall, or pause. This applies to any observable feature of labor, including but not limited to a slowing contraction pattern, or a stalling descent of the fetal head. Furthermore, this includes phenomena where labor is perceived to "reverse," including but not limited to a closing cervix or a rising presenting fetal part.31,34
Context
The context for this review is normal physiological labor. Definitions of normal labor vary, where common terminology includes the terms "physiological," "natural," "non-interventional," or "undisturbed labor."12,35 Where authors of publications report that labor was normal, this satisfies the inclusion criteria for this review. If the publication does not clarify whether labor was normal, the ICM definition will be applied: "normal childbirth [is] a unique dynamic process [[horizontal ellipsis]] where the woman commences, continues and completes labour with the infant being born spontaneously at term, in the vertex position [[horizontal ellipsis]], without any surgical, medical, or pharmaceutical intervention."32(p.1) It is anticipated that publications may not provide sufficient detail to establish whether labor was normal as based on the ICM definition (for example, information about pharmaceutical intervention may not be available). In such cases, this review will have an inclusive approach where we will consider labor as normal if the opposite was not stated. Simultaneously, exclusion criteria will apply to labor that is classified as pathological or that is subject to interventions known to affect the labor pattern (including but not limited to pharmaceutical augmentation or amniotomy).18,36 Finally, the context for this review is inclusive of all labor and birth settings.
Types of sources
The scoping review will be inclusive of all types of publications, including inter alia original studies, reviews, books and book chapters, opinion papers, and guidelines. Unpublished material will also be considered, for example, unpublished theses or dissertations. Both quantitative and qualitative research will be considered. Eligibility will be limited to the past 30 years (1990-2020) as this review aims to map contemporary concepts and definitions. No language limitations will be applied.
Methods
This protocol was designed in accordance with JBI recommendations and in alignment with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR).30,37
Search strategy
A three-step approach is recommended by JBI, where the first step is carried out before the scoping review protocol is developed, and the second and third step are conducted in the process of the scoping review itself.30
In the first step, we carried out an initial search in preparation for the scoping review protocol. The databases MEDLINE and Scopus, the Cochrane Library, and the Centre for Review and Dissemination (CRD) were searched between August and October 2019. This search was iterative and informed the keywords and index terms for the final search strategy. Furthermore, the search aimed to identify existing literature reviews in this area. Additionally, the reference lists of two relevant publications were screened to further inform the keywords and final search strategy.5,11 Based on this preliminary literature search, and with guidance from a professional subject librarian, we developed the final search strategy (Appendix I).
In the second step, we will apply the search strategy to multiple databases. The search strategy will be tailored to each database, with different truncation and proximity operators and index terms, where applicable. In the third step, we will screen reference lists of included publications to identify further published and unpublished material. Additionally, we will screen publication records of prominent authors in the field. Where applicable, we will contact authors of published or unpublished material to collect further information about their work.
The following databases were selected due to their relevance in the area of childbirth and midwifery: MEDLINE (PubMed), Embase, Emcare, and MIDIRS (Ovid), CINAHL (EBSCOhost), as well as Scopus. Gray literature and unpublished studies will be searched via Open Grey and through contacting researchers who work or worked in this topic area.
Study selection
All identified publications from the database search will be imported to EndNote V9.2 (Clarivate Analytics, PA, USA). Then, we will remove duplicate search results using the EndNote algorithm in a first step, supplemented by manual removal of remaining duplicates in a second step. Subsequently, we will screen results in two phases: based on title and abstract in the first phase and based on full-text review in the second phase. Decisions about inclusion or exclusion of a source will be based on the pre-specified inclusion and exclusion criteria reported in this scoping review protocol. Two reviewers will conduct the screening separately in a blinded manner, where the level of agreement between reviewers will be recorded for each phase of screening. Disagreements between reviewers will be resolved through discussion and, where necessary, through involvement of a third reviewer. All sources that are selected for full-text screening will undergo a reference list screening to identify further material. Reference list screening and contacting authors, where necessary, will be conducted by one reviewer. The number of search results for each database, number of retained sources during both screening phases, and exclusion reasons will be reported in a PRISMA flow diagram.37 Additionally, we will retain a detailed research record of the search process for the purpose of transparency, and will publish this as an appendix to the scoping review and/or make it available on request (depending on journal guidelines for the scoping review publication).
Data extraction
We developed and piloted a data extraction matrix (Appendix II). Extracted data will comprise information about the concept boundaries, varying terminology (if applicable), reported precedents and consequences of the concept, concept origin, and types of evidence that report this concept. Throughout the data extraction procedure, the matrix may be further refined to capture additional information. Any resulting adaptations will be highlighted in the scoping review publication. Data will be extracted by one reviewer and checked for accuracy by a second reviewer who will compare extracted data with the original document to ensure that all extracts represent the original wording and meaning. In cases of disagreement, a third reviewer will be consulted to resolve conflicts. Where publications are selected for inclusion in the review but lack detail for complete data extraction, we will contact the authors of the publication to request missing information. Furthermore, where sources are selected for inclusion but compiled in a language that is not spoken by the authors, we will seek translation support from a native speaker of this language to ensure data is extracted correctly.
Data presentation
Results of the scoping review will be presented in a table and supplemented by a narrative summary. Additionally, a diagram will present an overview of identified concepts in relation to their timing during labor (Figure 1).
In the discussion we will explore how different concepts and terminologies emerged, where they possibly overlap and what significance they have in maternity care practice. Concepts may be presented under categories if they share features; for example, where the timing of plateaus appears similar. Furthermore, we may suggest an umbrella term for groups of concepts or for the entirety of concepts of physiological labor plateaus. Overall, the planned scoping review will provide a comprehensive and timely overview of contemporary concepts of plateaus during normal labor and birth. Thereby, it will contribute to knowledge about normal labor and inform further research in this area.
Acknowledgments
Lisa Webb, librarian, for her support in development of the search strategy.
Funding
The Australian Government funded this work through an Australian Government Research Training Program Scholarship as part of an ongoing PhD (Health) degree for MW.
Appendix I: Search strategy
MEDLINE (PubMed)
Searched on March 24, 2020, limited to publications in the year 1990 or thereafter. Keywords and index terms (MeSH) were applied.
Appendix II: Data extraction instrument
References