Measuring women's empowerment during the perinatal period in high income countries: A scoping review of instruments used

Abstract

Empowerment is acknowledged as a process facilitating those who are less powerful to be engaged in their problem identification, decision making and actions to gain control over their life. This is an important goal for women during the perinatal period in their transition to motherhood. A concept analysis of women's empowerment during the perinatal period found that psychological and social dimensions play a role in women's perinatal empowerment and identified several defining attributes.

The aim of this study was to identify robust validated instruments that measure all the attributes of women's empowerment during the perinatal period.

We did a scoping review of scientific literature following the methodology of the JBI Reviewer's Manual. We searched the database MEDLINE, CINAHL, PsycINFO, PsycARTICLES and SocINDEX and selected papers meeting the inclusion criteria. Instruments measuring empowerment or related concepts were identified in the selected papers. Two authors independently cross referenced the items of each instrument against the defining attributes for empowerment.

Our search resulted in 9771 unique hits of which 36 papers were finally included. Studies were from various countries with a wide variety of aims, demographics of cohorts and timepoints across the perinatal period. Twenty-one different instruments were used to measure empowerment, of which 11 were validated among women during the perinatal period. However, no identified instrument was developed specifically for women during the perinatal period or included all the dimensions of empowerment and the defining attributes.

There is a need for a theoretically sound valid and reliable instrument measuring all the dimensions of empowerment of women during the perinatal period. Once developed this instrument needs testing with a broad range of women. Results from such a study will inform the development of appropriate interventions that have a coherent theoretical basis and are empirically informed to enhance women's empowerment during the perinatal period.

Highlights

• •Women's perinatal empowerment in high income countries is vital for their health.
• •Women's empowerment in the perinatal period has internal and external attributes.
• •No instrument has been developed to measure women's perinatal empowerment.
• •No instrument measures all defining attributes of women's perinatal empowerment.

1. Introduction

Empowerment as a concept in health gained momentum with its inclusion in the definition of health promotion [1]. In this context, it can be seen as a complex goal to include political, academic, economic, welfare, health and equality aspects [2]. Empowerment is also acknowledged as a process where those who have been disempowered are facilitated to be engaged in their problem identification, decision making and actions so they establish control over resources and capacity in terms of health related outcomes [3]. The Sustainable Development Goals (SDGs), with SDG 3 focused on ensuring healthy lives and promoting well-being for all, begins in pregnancy [4]. Empowerment of women during the perinatal period has received much attention in terms of the linkages with promotion of gender equality and improvement of maternal and infant outcomes [5,6]. Maternal pregnancy health and birth outcomes that matter most to women were explored in a meta-synthesis of 35 studies from 19 countries [7] and results indicated that a positive childbirth experience was paramount. Key contributing factors included the woman being at the centre of her care and engaged in decisions fundamental in determining birth processes, whilst maintaining dignity and control in a safe empathetic environment. The findings apply directly to women of all parity, and in a range of cultural and economic settings receiving routine intrapartum care. The review included studies of participant women with a broad range of demographic, health and pregnancy risk characteristics. For example: women with specific health conditions, such as HIV or diabetes; women from particular marginalised groups, such as those seen as ethnic or cultural outsiders; very young and very poor women. Furthermore, women from these groups were part of the respondent sample in some of the included studies, and individual studies on the views of marginalised women suggest that the review findings are highly likely to be transferable to all women. The key contributing factors to a positive childbirth experience articulated by these women reflect the principles of the concept of empowerment [8]. Research to date has comprehensively examined the concepts of perinatal choice, control and informed decision making [7,8], and the commonality within conclusions of such studies, is the recommendation for women to be empowered without articulating what this entails.

An acknowledged difficulty for researchers is an agreed comprehensive definition of the concept of empowerment of women [8]. A frequently used definition is that proposed by Kabeer who conceptualises empowerment of women as their ability to make strategic life choices in three dimensions: socio-cultural, economic and psychological. The first dimension refers to gender equality and includes education and the acceptance of women making their own decisions [9]. The second refers to right to and control over their means on making a living and may also include resources, such as capital. The third and final dimension refers to having the self-esteem, self-efficacy and capability to make choices [9]. Nieuwenhuijze and Leahy-Warren conducted a concept analysis of a woman's empowerment throughout the perinatal period in order to further expand this notion and discovered that the distinguishing characteristics are both internal and external to the woman. Gender equality, control over resources, and support for women's decision-making are examples of external attributes. Women's internal attributes include their self-confidence and sense of control over their circumstances, selves, and others [8].

While several studies have measured women's empowerment as a core concept [[10], [11], [12]], instruments that measure the full scope of dimensions and defining attributes of empowerment seem scarce. Studies from low/middle-income countries (LMIC) predominantly focus on at least three empowerment dimensions (psychological, social, economic, legal or political), and frequently consider both the individual and collective aspects of empowerment [[13], [14], [15]]. Studies from high-income countries focus on the individual aspect of empowerment, mainly the psychological dimension [16,17] occasionally combined with the social dimension [18,19]. Still, also in high-income contexts the other dimensions are important for many women to achieve empowerment.

Pratley [20] concluded from a systematic review of women's empowerment in low-income countries that the instruments used to measure women's empowerment varied widely and did not aggregate indicators into meaningful dimensions. No systematic review on the constructs included in instruments to measures women's empowerment during the perinatal period has been conducted in high-income countries to date. Moreover, while the focus of Pratley's [20] review was on maternal and child outcomes in LMIC, the focus of a systematic review of evidence on the impact of empowerment in high-income countries also needs to consider the contexts of studies and how empowerment was defined and measured. Therefore, this paper presents a scoping review to include a synthesis of the instruments that measure women's empowerment during the perinatal period in high-income countries. The perinatal period, here defined as pregnancy up to the first six weeks postpartum. A cross analysis of the defining attributes from the concept analysis was used to assess instruments used in high-income countries to identify a robust validated instrument that has sound psychometric properties to measure women's empowerment during the perinatal period. Our study is unique and contributes to the previous body of literature in that the aim is to compare and contrast all published available instruments that measure empowerment of women in the perinatal period and analyse, synthesise to identify possible gaps.

2. Method

In order to identify instruments measuring women's empowerment during the perinatal period we performed a scoping review of scientific literature using the methodology as described in the JBI Reviewer's Manual [21]. We chose a scoping review, as we wanted to do a broad exploration of available instruments. Subsequently, we compared the identified instruments against the defining attributes of our concept analysis of women's empowerment in the context of the perinatal period [8].

2.1. Search strategy for the scoping review

For the scoping review, we performed a literature search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews [20]. We searched EBSCO-host, including the database MEDLINE, CINAHL, PsycINFO, PsycARTICLES and SocINDEX, using the key concepts ‘empowerment’, ‘woman’, ‘childbirth’, ‘outcomes’, ‘design’ and their synonyms (Table 1). The concept ‘empowerment’ included related concepts as identified in the concept analysis of women's empowerment during the perinatal period [8]. The search was conducted in December 2019 with an update in March 2022. Limitations were set for publications from 1999 onwards and the English language. Reviews and reference lists of included papers were searched to identify additional relevant papers.

Table 1.

Search terms.

Key concept	Empowerment		Woman		Childbirth		Outcome		Design
Search terms	AB empower* OR power OR autonomy* OR agen* OR self-effic* OR “self effic*” OR control OR (decision AND making) OR decision-making	Ap2pNp2pD	AB wom* OR mother* OR maternal* OR primip* OR multip* OR paturient* OR female*	Ap2pNp2pD	AB childbirth OR “child birth” OR child-birth OR birth* OR labour OR labor OR delivery OR intrapartu* OR intra-partu* OR perinatal OR pregnan* OR antenatal OR antepartu* OR ante-partum OR postnatal OR postpartu* OR post-partu*	Ap2pNp2pD	AB (outcome* OR ((maternal OR child) AND (health OR mortality OR morbidity)) OR ((maternal OR child) AND (obstetric* OR maternity OR perinatal)))	Ap2pNp2pD	AB quantit* OR survey* OR questionnaire* OR tool* OR measure* OR instrument*

To select relevant papers, both authors independently read the abstracts and selected full papers, we discussed differences until consensus was reached. We focused on studies with populations from high-income countries as Pratley [20] had done an exploration for quantitative measures of empowerment in LMIC.

We approached perinatal empowerment as the ability of women to make strategic life choices specifically related to perinatal domain, in line with the definition in the concept analysis. The inclusion criteria were: (1) publications in peer reviewed scientific journals, (2) describing original research using an instrument to measure perinatal empowerment or related concepts (such as power, self-efficacy, autonomy, control, agency or decision-making power), (3) among women during the perinatal period from (4) high-income countries. We excluded papers that (1) focused on empowerment of fathers or care providers, (2) explored empowerment in the context of contraception or abortion care, (3) linked empowerment to one specific behaviour e.g. management of weight gain, gestational diabetes, breastfeeding, (4) studied empowerment solely in low- and medium-income countries. We used the definition of the World Bank for the identification of high-income economies [22].

No quality assessment of the individual papers took place as we are not analysing the ‘findings’ from the studies as such, but the way empowerment was measured.

2.2. Data extraction and analysis

Instruments measuring empowerment or related concepts were identified in the selected papers. We designed an extraction table (Appendix 1) which included information on: authors, publication year, country, aim/research question, design, participants, setting, instruments used, data collection, analysis and outcome. This table presents the context in which women's empowerment was examined and how it was measured. This informed our in-depth analysis of the instruments, which was guided by the following research questions: (1) what concept does the instrument measure? (2) what are the dimensions and questions/statements in the instrument? If this was not clearly stated in the paper, the original paper on the development of the instrument was retrieved (3) in what populations was the instrument validated (4) how does the content of the instrument relate to the defining attributes of the CA? To answer the last question, the two authors independently cross referenced the items of each instrument against the defining attributes for empowerment as described in the concept analysis (box 1). Differences were discussed and settled through consensus.

Box 1. Defining attributes of empowerment [8].

External attributes.

• •Gender equality (interpreted as respect/general equality/equity)
• •Access to and control over resources (such as support, information)
• •Facilitation of choice and decisions

Internal attributes.

• •Belief in own abilities
• •
  Control over

  • o
    Self
  • o
    Others
  • o
    Situation

Alt-text: Box 1

3. Results

Our search resulted in 9771 unique hits. Based on title and abstract, we selected 245 papers. We were able to retain 243 full papers of which 32 matched our inclusion criteria (Fig. 1). Four additional papers were found in reviews or reference lists of included papers and the final number was 36 papers.

Fig. 1.

PRISMA flow diagram.

3.1. Characteristics of the included papers

Studies were conducted across many countries with the majority undertaken in the USA (n = 14) [[10], [11], [12],16,[23], [24], [25], [26], [27], [28], [29], [30], [31], [32]] 5 in Australia [18,[33], [34], [35], [36]]; 4 in Sweden [[37], [38], [39], [40]]; and the UK [17,19,41,42]; 3 in Canada [[43], [44], [45]]; 2 in the Netherlands [3,46] and Japan [47,48] and one study in Greece [49] and New Zealand [50].

Study aims varied from examining childbirth self-efficacy (n = 9); sense of control during labour (n = 11), testing educational interventions (n = 4); comparing different models of care with some studies testing psychometric properties of their instrument. Participants' included nulliparous and multiparas and also one study included women who were planning a pregnancy [32]. Time points of data collection varied with the majority (n = 13) collected in the antenatal period; 12 in the postnatal period and 7 collected data across the perinatal period. Data collection settings varied from clinics that provided midwifery-led care; hospital settings; ultrasound clinic; birth centers; participant's own home and online. Studies with more than one time point of data collection had various settings e.g. antenatal clinic, hospital and participant's home. See appendix 1 for further details.

3.2. Measurements used to examine empowerment

We identified 21 different measurements that were used to examine empowerment or related concepts in women during the perinatal period. However, two measurements could not be further explored as one was unavailable [11] and the other was in Japanese [47], leaving 19 measurements to be further explored (Table 2).

Table 2.

Measurements^a used in the selected papers.

	Name	Used in which study	Concept	Dimensions/factors	Validated
1.	Birth Satisfaction Scale (BSS)	[24]	Assesses women's birth perceptions.	•Quality of care provision •Woman's personal attributes (e.g. feeling in control) •Stress experienced during labour	Content validity based on literature. BSS-RI was validated with a random selection of mothers who had given birth in England. Also validated in Spanish, Italian, Brazil, Iran and Slovakia [50,65]
2.	Childbirth Experience Questionnaire (CEQ)	[39]	Assesses different aspects of mothers' childbirth experiences.	•Own capacity •Professional support •Perceived safety •Participation	Primiparous women after childbirth in Sweden. Also validated in Iran, China, Sri Lanka, UK, Danish and Portuguese [51]
3.	Childbirth Self-Efficacy Inventory (CBSEI)	[17,22,33,34,[36], [37], [38],48,49]	Measures women's outcome expectancies and self-efficacy expectancies for coping with an approaching childbirth experience.	•Outcome Expectancy Active Labour (Outcome-AL) •Self-Efficacy Expectancy Active Labour (Efficacy-AL) •Outcome Expectancy Second Stage (Outcome-SS) •Self-Efficacy Expectancy Second Stage	In a sample of predominantly Caucasian pregnant women in USA. Also validated in Spanish, Thai, German, Chinese, Singapore, Indonesia, Greece, Iran, Australia and Sweden [52]
4.	Decision Control Subscale of the Decision Evaluation Scales	[29]	Measures psychological factors that play a role when patients evaluate their medical treatment choices.	•Satisfaction-uncertainty •Informed choice •Decision control	Women with and without breast/ovarian cancer who had chosen to undergo DNA-testing in the Netherlands [61]
5.	Empowerment score	[31]	Measures the personal construct of empowerment as defined by consumers of mental health services (e.g. decision-making power, access to information and resources, assertiveness).	•Self-esteem/self-efficacy •Power-powerlessness •Community activism and autonomy •Optimism and control over the future •Righteous anger	Members of six self-help programs in USA [62].
6.	Green - 9 questions on control	[16]	Assess women's sense of control as a major factor contributing to a woman's birth experience.	•Internal control •External control of behaviour •Control during labour	Not validated
7.	Homer - 17 statements on confidence, control and anxiety	[32]	Measures women's confidence in caregivers, levels of control and anxiety, involvement in decision making and the provision of information.	•Confidence •Control •Anxiety •Decision making •Information	Not validated
8.	Kim Alliance Scale (KAS-R)	[27]	Measures the quality of therapeutic alliance between patient and care provider.	•Collaboration •Integration •Empowerment Communication	Nurses (as patients) and outpatients from two clinics serving military family members and retirees in USA [63]
9.	Labour Agentry Scale (LAS-29)	[19,41,43,47]	Measures women's expectations and experiences of personal control during childbirth.	–	English-literate pregnant women with uncomplicated births in Canada. Also validated with pregnant women in Japan and China [53]
10.	Levenson Internality (I), Powerful Others (P), and Chance (C) Scales	[28]	Measures women's internal and external dimensions of locus of control.	•Internality •Powerful others •Chance	Diverse non-pregnant groups in USA [64]
11.	Mother's autonomy in decision making (MADM)	[30,44]	Assesses women's autonomy and role in decision making during maternity care.	–	Pregnant women in Canada seeing midwives, obstetricians and physicians. Also validated in Dutch [55]
12.	Mothers on respect index (MORi)	[30,44]	Assesses women's experiences with maternity care, including disrespect and discrimination.	–	Pregnant women in Canada seeing midwives, obstetricians and physicians. Also validated in Dutch [55]
13.	Perceived control in childbirth scale (PCC)	[35]	Assesses women perceptions of control of the childbirth environment.	–	Mainly Caucasian women after birth in the USA [56]
14.	Pregnancy-related Empowerment Scale (PRES)	[11,25]	Evaluates women's empowerment to take control of their health.	•Provider connectedness •Skilful decision-making •Peer connectedness •Gaining voice	In a sample of African American, Latino and Caucasian pregnant women in USA [11].
15.	Prenatal Interpersonal Processes of Care (PIPC)	[2,15],	Assesses what happens between care providers and pregnant women.	•Communication (sub-dimension empowerment) •Decision making •Interpersonal style	In a sample of African American, Latino and Caucasian pregnant women in USA [57]
16.	Questionnaire Measuring Attitudes About Labor and Delivery (QMAALD)	[42]	Assesses women's perception of her childbirth experience.	–	Unclear [59]
17.	ReproQ/Maternal Empowerment Questionnaire (MEQ)	[2,45]	Assesses women's experiences with the responsiveness/performance of maternity care system.	•Dignity •Autonomy •Confidentiality •Communication •Prompt attention •Social consideration •Basic amenities •Choice and continuity	Pregnant women and women who had recently given birth in the Netherlands [58]
18.	Self-esteem and Mastery (Sense of Personal Control) Scale	[67]	Assesses women's psychosocial resources in pregnancy.	•Self-esteem •Mastery	Unclear [60]
19.	Support and Control in Birth (SCIB)	[18]	Measures women's experience of support and control in birth.	•Internal control •External control •Support	Postpartum women in the UK, including women with a traumatic birth [18]

^aTwo measurements could not be further explored as one was unavailable (Empowerment measurement in Kovach et al., 2004) and the other was in Japanese (Childbirth Self-efficacy Scale in Takeuchi and Horiuchi, 2016).

Measurements used to examine empowerment varied from author developed questions to use of instruments developed to measure some component/domain of empowerment.

In the 36 selected papers, the Childbirth Self-Efficacy Inventory (CBSEI) was used in eight different studies and the Labour Agentry Scale (LAS) in three, with the remainder being used only once (n = 11) or twice (n = 6).

The measurements included 11 instruments that underwent some form of validation with women during the perinatal period [12,19,[51], [52], [53], [54], [55], [56], [57], [58], [59]]. Two measurements were not validated [16,32], for two this was unclear [60,61]. Another four instruments were validated with women in the context of breast/ovarian cancer/mental health [[62], [63], [64], [65]]. Six instruments (BSS, CEQ, CBSEI, LAS, MADM and MORi) were validated in more than one country or language.

As illustrated in Table 2, the instruments assert to measure a wide range of concepts, such as women's experiences or expectations of empowerment, self-efficacy or sense of control during childbirth, women's perceptions or experiences of childbirth in general, women's relationship with their care providers, women's participation in decision-making, or women's empowerment to take control of their health. To explore these measurements in greater depth, we cross referenced the items of the available validated instruments with the defining attributes of the concept analysis [8].

3.3. Cross reference of instruments with the defining attributes of the concept analysis

Findings from the concept analysis on women's empowerment during the perinatal period, identified the defining attributes as external and internal to the woman (see Box 1). Comparing the content (items) of the 15 validated instruments with these attributes is illustrated in Table 3.

Table 3.

Comparison between content of validated instruments and defining attributes from the concept analysis [7].

Questionnaire, reference	Number of the instrument's item indicating defining attributes of empowermenta
	Internal attributes				External attributes
	Belief in own abilities	Control over			Gender equality (interpreted as respect/general equality/equity)	Access and control of resources (such as support, information)	Facilitation of women's choice and decisions
		self	others	situationa. b. c.
Birth Satisfaction Scale (BSS; [65]	15	1,4,16,18				3,10,17, 21,24,25,27	2
Childbirth Experience Questionnaire (CEQ; [51])	3	2,4,5,14	12	1,6,8		9, 10, 11,13,18	20, 21, 22
Childbirth Self-Efficacy Inventory (CBSEI; [52]) (comparison with the CBSEI Efficacy items)	16/47, 17/48, 18/49, 24/55, 27/58, 29/60	19/50, 22/53, 26/57				30/61, 62
Decision Control Subscale of the Decision Evaluation Scales [61]	3,4,5		1				2
Empowerment Score [62]	1,2,3,5,7, 8,9	4,6,10, 13,18,19		23,24,25,27
Kim Alliance Scale Revised [63]					5,6,7,8	11,15	1,10,12
Labour Agentry Scale (LAS; [53])	1,7,9,24	5,8,11, 12,17, 19,23	13,27	2,3,14,15, 16,20, 22,29	21,25	6
Levenson I, P, and C Scales [64]	1,5,7, 16,18,	2,20,21, 23	3,8,11, 13,17,24	2,6,10, 12,14,19
Mother's Autonomy in Decision Making [54]					7	2,3	1,5,6
Mothers On Respect index (MORi; [55])			1-5,8-10		6,7,11-14
Perceived control in childbirth scale (PCCs; [56])			4,12	3,5,6,8,10		7,9,11	1,2
Pregnancy-Related Empowerment Scale (PRES; [11])	8,14,15	7,9		13	4	1,2,3,11,16	5,6
Prenatal Interpersonal Processes of Care (PIPC; [57])			5,6,7,8		15-21,26-30	9,10,22-25	11–14
Repro-Q/Maternal Empowerment Questionnaire (MEQ; [58])					1-6,25	14-19, 23, 24, 26	7-10, 32
Support and Control in Birth (SCIB; [18])		1–10	14,17	11-13, 16,21		18-20,22-33	15

^aNot all items of an instrument were included as some could not be linked to any of the defining attributes.

It is evident that there is wide variability in terms of whether instruments measured both internal and external attributes and furthermore whether all dimensions of the attributes were included for measurement. Five instruments did not measure both internal and external attributes, but this varied as three did not measure any internal attributes: KAS-R, [64]; MADM, [55]; Repro-Q/MEQ [59], and a further two did not measure any external attributes: Empowerment Score [63], and the Levenson I, P, and C Scales [65]. Furthermore, access and control of resources as external attributes were not included in four of the instruments [56,62,63,65]. Given the importance of social support, particularly relationship stability for women during this period, it is imperative that any measure of empowerment includes this attribute.

A number of instruments focus on a specific aspect of the perinatal period, such as prenatal (PIPC [58]) pregnancy (PRES, [12]), and childbirth [19,[52], [53], [54], [55], [56], [57],66]. Moreover, some are further limited to one dimension of empowerment such as respect (MORI, [56]) and thus include dimensions relating only to the internal attribute of control over others and the external attribute of gender equality. While two instruments focus on maternity care (Repro-Q [59], and MADM, [55]), the only dimensions included are those related to external attributes.

Therefore, no identified instrument includes or reflects all the dimensions of empowerment of the defining attributes from the concept analysis.

4. Discussion

We identified 21 different instruments that measured empowerment or related concepts among women in high-income countries during the perinatal period. Eleven of these instruments were validated among women during some time point along the perinatal period but not the whole perinatal period.

A further analysis of these instruments showed that the majority focused specifically on one aspect of the perinatal period, e.g. birth. Additionally, all instruments are limited further in measuring the number of dimensions reflecting the defining attributes identified in the concept analysis. For example, some instruments reflect only internal attributes and other instruments measure only external attributes. A few instruments have a limited combination of both, but not one instrument includes all dimensions of the defining attributes of the concept analysis. It is evident that there is no instrument that fully measures empowerment of women during the perinatal period in high income countries.

When empowerment of women is examined in low-income countries, it is measured within the broader socio-cultural-economic-political landscape rather than the reductionist approach of psychological context [20]. In considering the significance of pregnancy and childbirth as the cornerstone to population health, it is imperative that all dimensions and defining attributes are included in the measurement of empowerment, also in high-income countries. Many studies in high-income countries show that the circumstances in which pregnant women live has an effect on their childbirth outcomes and on the control they have over their own health and that of their families [3,67]. Inclusion of both external and internal attributes in examining empowerment of women during the perinatal period across LMIC and HIC will provide a baseline for developing interventions that have a coherent theoretical basis, are empirically informed and are robust. Use of such an instrument will allow for thorough exploration of the links between women's empowerment and health outcomes during the perinatal period internationally. In addition, it can facilitate the translation of knowledge across and within diverse cultures economies and political environments.

4.1. Strengths and limitations

This is the first scoping review exploring the availability of established tools that gauge women's empowerment throughout pregnancy. Some pertinent studies may not have been included in this review because of the database selection (i.e., searching additional databases may have identified more pertinent studies), the exclusion of studies published in languages other than English, and grey literature from the search may be seen as limitations of this review.

5. Conclusion

In conclusion, in the absence of a robust psychometrically tested instrument that reflects all attributes of women's empowerment during the perinatal period, there is a need for further research to develop an instrument informed by women that includes all the dimensions of empowerment and is psychometrically sound. This instrument needs to include dimensions that reflect all of the defining attributes, both internal and external and be compatible for use with women during the perinatal period in low- and middle-income countries and in high-income countries. Such an instrument would facilitate the assessment of empowerment of women during the perinatal period internationally so that interventions that have a theoretical basis and are informed by women can be developed to meet specific healthcare needs of women during the perinatal period.

Author contribution statement

Patricia Leahy-Warre, Marianne Nieuwenhuijze: Conceived and designed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.

Funding statement

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Data availability statement

Data included in article/supp. material/referenced in article.

Declaration of interest's statement

The authors declare no competing interests.

Appendix A. Supplementary data

The following is/are the supplementary data to this article: