Women’s Vocalization in the First and Second Stages of Labour: A Scoping Review Protocol

Abstract

Taking into account the growing increase in the political and social interest in childbirth, it is critical to identify and explore the instruments that allow and enhance its humanization today. The use of vocalization seems to be a powerful and empowering tool for a positive birthing experience when used by women in labour. A scoping review will be developed to map the evidence and knowledge about women’s vocalization in the first and second stages of labour using the Joanna Briggs Institute methodology. The search will be carried out on the Web of Science, EBSCOhost Research Platform (selecting Academic Search Complete, MedicLatina, Cinahl plus with full text, Medline with full text), Willey Online Library, PubMed and Scopus. The National Register of Theses and Dissertations and the Open Scientific Repository of Portugal will also be taken into account. Three reviewers will conduct data analysis, extraction and synthesis independently. The outcomes pretend to be a source for identifying the use of vocalization by women in labour, in order to guide further research on the subject. This study was prospectively registered with the Open Science Framework on the 21 May 2024, with registration number DOI 10.17605/OSF.IO/Z58F4.

1. Introduction

Historically, births used to take place at home, making the experience unique to the feminine cosmos women [1]. The house served as a safe and protected environment [2]; however, the institutionalization of birth, despite being more effective in reducing maternal and newborn mortality and morbidity than home-based delivery [3], caused a disruption of the physiological birthing process [4]. Since the middle of the last century, various authors like Balaskas [5], Frédérick Lebouyer [6], Sheila Kitzinger [7] and Odent [8], among others, have spoken out against the medicalization of childbirth, and have called for a return to natural childbirth, which allows women to follow their natural instincts and body’s physiology, breathe at their own pace and vocalize according to personal needs. During the first and second stages of labour, women have used vocalization for centuries, instinctively and spontaneously, with sounds such as screams, roars, groans and sighs, grunts, howls or cries [9,10].

The WHO [11] defines labour in three phases, as follows: the first phase corresponds to the dilation of the cervix up to 10 cm, which is associated with painful uterine contractions; the second phase is between the complete dilation of the cervix to 10 cm and the birth, which is associated with an involuntary desire to push; and the third phase is the period after the birth until the placenta is delivered. In a natural birth, the reduced activity of the neocortex makes the woman’s behaviour similar to that of other mammals, bringing her into an altered state of consciousness with the adoption of instinctive behaviours such as vocalization or the quadrupedal posture [12,13]. As the neural connections of the two linguistic and non-linguistic areas diverged, humans evolved voluntary control of vocal production for speech and singing, maintaining the older phylogenetic system of non-verbal languages, such as laughing and screaming [14]. Vocalization is an ancient trait of vertebrates, not exclusive to humans, that is crucial to many types of communication [15]. The vocalization system of mammals is innate in the first place. In other words, it is rigid, emotional, independent and does not rely much on social learning [16]. In human vocalization, marginally articulated open vowels prevail, with modulation of the vocal source conveying affection [17]. Intentional vocalization in labour is defined as expressing the exhalation of the breath in a single tone, with an open glottis, such as a vowel sung like A, O and U, or humming in a low tone, both of which have potential mental and physical benefits for women [6,18,19]. The use of intentional vocalization by women in labour is also known as vocal toning [18], the vocalization breathing method for labour [19] or even prenatal singing [20,21]. Prenatal singing, which was first developed in French maternity wards in 1960 by Marie-Louise Aucher [20], is a conscious and focused vocalization that tries to prepare pregnant women for labour contractions by employing exhaled air as a sound massage of the pelvic [21]. Directed vocalization or a respiratory technique in the second stage of labour is shown to have a beneficial impact on pelvic injury, and is directly related to less severe pelvic lacerations [19,22]. Vocalization in labour has been linked to improved pain control because it appears to relax the mouth and, as a result, the respiratory diaphragm, abdomen and perineum [21,23]. The vibration that goes through the body during vocalization can help women cope with and relieve pain during delivery. The use of vocal training techniques, which are commonly utilized by actresses during labour, suggests that they can help with pain alleviation [24]. Active listening to women’s vocalizations during birth can provide caretakers with vital information on how women cope with labour [9].

The WHO [11] recommends using the open glottis breathing technique during the second stage of labour, rather than the Valsalva Manoeuvre or closed glottis breathing technique. The open glottis technique, used by women during contractions in the second stage of labour, involves prolonged exhalation in one breath, in tune with the contraction of the abdominal muscles. With this technique, health professionals encourage the woman to make spontaneous expulsive efforts. During the use of the closed glottis technique, or Valsalva Manoeuvre, guided by health professionals, the woman remains in apnoea when performing expulsive efforts directed at the time of contraction [22]. Although the results of the scientific evidence analyzed by the WHO comparing the use of the open glottis respiratory technique to the closed glottis suggest that there are no significant differences with regard to the following factors—perineal or vaginal trauma in the short- or medium–long-term, duration of the expulsive period, the need for an instrumented delivery, maternal satisfaction or fetal or neonatal complications—the first technique is recommended by the WHO [11]. The main advantage to using the first technique over the second is that it gives back control over labour to women, concluding that the support given to women must respect their choice [11]. Other studies have found advantages in opening the glottis during contractions in the second stage of labour, namely the protective effect of perineal trauma, less maternal and fetal distress [22], reduced pain in the parturient, a better acid–base balance in the fetus [25] and a reduction in the duration of the second stage [26].

Despite the relevance that vocalization appears to have as a beneficial resource for a fulfilling and satisfactory delivery experience, previous database studies have revealed that there is little empirical evidence in this area of expertise. With the existing scientific evidence on the use of women’s vocalization in the first and second stages of labour through the scoping review and based on the current protocol, we aim to achieve results that promote further research on the subject. Based on this protocol, new investigations could be carried out to contribute to the conceptualization of women’s vocalization in labour. In this way, we hope to launch a debate on this topic, particularly in the context of childbirth in our country. We also wish to contribute to the promotion of woman-centred care. Respectful maternity care has been recognized and recommended by international organizations such as the WHO [11] over the last few years, in a holistic and integrative approach to the culture of birth [27].

Objective

The goal of this scoping review is to map the existing scientific evidence on women’s vocalization in the first and second stages of labour.

2. Experimental Design

This protocol is in agreement with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Extension for Scoping Reviews (PRISMA-ScR) procedures. PRISMA-ScR will show the flow of information throughout the phases of the review, i.e., the articles eliminated, selected, included/excluded and the reasons for this [28].

Through this scoping review protocol, we intend to launch an analysis of women’s vocalization during the first and second stages of labour. The research stages of the scoping review comply with the guidelines of the Joanna Briggs Institute (JBI) [29]. Firstly, the research question is defined, then the relevant studies are identified and selected, then the data is extracted and, finally, the results are compiled, summarized and reported.

A scoping review was chosen as the ideal study to map, clarify and develop an overview of vocalization of women in labour. It seeks to identify experiences, facilitating factors and barriers in a broad approach [30].

Construction of the protocol started in January 2024, and the scoping review is projected to be finalized in August 2024. This protocol is registered in the Open Science Framework platform with the following registration number: DOI 10.17605/OSF.IO/Z58F4.

Research Question

The research question to be answered by the scoping review was defined according to the acronym PCC (Population, Concept, Context) [31] and is as follows:

What is known in the literature about the use of vocalization (Concept) by women (Population) in the first and second stages of labour (Context)?

3. Materials and Equipment

The search strategy aims to locate and access the various types of scientific academic production. In the search strategy, an initial phase is envisaged, which will be limited to the approach to the topic in the Web of Science. In Appendix A, the search strategy established for the Web of Science database can be found. The database search strategy will be adapted to each database or source of information considered. Search terms include “vocalization”, “woman”, “labour, obstetric”. Different spellings will be used, for reasons of different application in the same language. For example, “labour OR labor” are used to mean the process of giving birth, respectively, in the UK and USA English variants.

The databases for white literature include the Web of Science, EBSCOhost Research Platform (selecting Academic Search Complete, MedicLatina, Cinahl plus with full text, Medline with full text), Wiley Online Library, PubMed and Scopus. These will be accessed via the Education Roaming network (EDUROAM), accessed at the University of Évora.

The search terms will be adjusted for use in each database, in combination with specific filter, respectively.

4. Detailed Procedure

4.1. Inclusion/Exclusion Criteria

The inclusion and exclusion criteria for the research study were determined based on the PCC question (Population, Concept and Context) (

Table 1. Inclusion/ exclusion criteria table.

Strategy	Inclusion Criteria
Population	Studies that discuss aspects related to vocalization of women in labour.
Concept	Studies that report the scope of the conception of vocalization.
Context	Studies concerning the assistance to the labor development, in any birth place, including public and/or private care.
Other Criteria	The scoping review will consider a large approach of studies. Studies of a qualitative and quantitative type, of all ranges, whether descriptives, experimental, quasi-experimental, case studies or case reports, literature reviews or meta-analyses. Other publications, like national or international sources of representative institutions, will be considered in this review. There will be no restrictions of the publication period. This scoping will consider documents in the English, Portuguese, Spanish, French and Italian languages.
	Exclusion Criteria
	The exclusion criteria comprised studies that do not contribute to the question of not discussing these aspects.

).

4.2. Selection Process

Studies selected to be included in the scoping review met the inclusion criteria mentioned above. As the search is carried out in each database, the texts identified will be sent to the RAYYAN [32] revision manager. Duplicates will be removed automatically by the manager, or manually when not identified. The grey literature will be exported to an Excel file. In the RAYYAN manager, three independent reviewers will initially scrutinize the texts, considering “included”, “excluded” and “maybe”, through the title and abstract, and eliminating those that do not fulfil the previously stipulated inclusion criteria. Once the selection has been finalized, conflicts and tie-breakers will be resolved by introducing a fourth reviewer. An independent reading of the full text by three reviewers will be the next step. The inclusion of any study, derived from the articles analyzed, will not be conditioned by methodological limitations or risk of bias of the evidence, as scoping reviews aim to offer a global vision or map of the evidence, and not a mandatory critical appraisal [33]. The use of a Prisma Scoping Review^® flowchart [28] will provide a systematized presentation of all of the steps taken in the selection of studies and, consequently, the results achieved.

4.3. Data Extraction

Three independent reviewers will extract the data from the texts included in the scoping review. A tool designed for this purpose will be used for this extraction, which can be found in Appendix B. This data extraction considers at least the following information: author, year, population, results and relevant conclusions, among others, related to the review question. The table will be improved during the course of the review as necessary. Conflicts between the three reviewers will be discussed and/or considered by a fourth reviewer. If necessary, in cases of clarification, the original authors will be contacted as far as possible to obtain information, missing data or other information.

4.4. Compiling, Summarizing and Reporting the Results

The RAYYAN software will be used independently by three reviewers to analyze the text. Texts that have been excluded must state the reason for their exclusion. To summarize the results achieved through data extraction, a table will be created. In order to answer the research question of the scoping review, this table will comprehend the following information: title of the study analyzed; author(s) and year of publication; type of study used; objective(s) to be achieved; population involved; methodology chosen; results and main conclusions obtained and final findings (Appendix C) [34]. A narrative summary will accompany the results, also taking into account the research question. We will present existing knowledge on the subject under study, gaps in the literature, as well as possible implications for health and research.

This scoping review seeks evidence from published studies for secondary data, so ethical approval is not required.

5. Expected Results

The unrestrained and unrestricted use of the voice appears to improve the contentment and autonomy of women in work [25], particularly the empowerment of parturients. According to the same authors, vocalization during labour is so innate and ubiquitous that it is an unavoidable component of the process, and eliminating it can alter the birth process. The lack of literature reviews on the issue endorses mapping the scientific data in order to formulate the definitions of the subject under research and identify the topic’s conceptual constraints [33]. At this point, we hope to strengthen information on the subject, launching a debate at both the national and international level, with a particular focus on our country. The results obtained through this analysis can contribute to recognising the importance of vocalization as a freeing act, essential to providing respectful maternity care. It could also be integrated into practical guidelines for the provision of care to women in labour, in a woman-centred vision that takes into account the women’s opinion, her autonomy and dignity.

6. Strengths and Limitations of the Study

This scoping review suggests that this subject is innovative, given that, as far as we can see, there are no secondary studies on vocalization in labour. We expect to provide a basis for respectful care with a better understanding of the physiological phenomena of normal labour.

In order to minimize the lack of evidence on the subject of women’s use of vocalization in the first and second stages of labour, we opted to search for studies without any time limit. This could still be a limitation if, after selecting the studies, no relevant information was obtained and publications that did not fulfil the inclusion criteria were found.

We defined four languages to analyze, which may also be a limitation.