The first stage involved identifying key search words and terms (Table 1). Research and academic keywords and Medical Subject Headings terms (eg, Anxiety AND Pregnancy) were piloted on Android (Google Play, Google) and iOS (App Store, Apple). These search terms led to limited results and did not locate preidentified “marker” apps (Mind the Bump [32] and Headspace [33]). The Headspace and Mind the Bump apps were selected as marker apps because they are recommended by the National Health Service or established mental health charities. General phrases were brainstormed by the review team, considering terms that women may use to search for resources as well as descriptive and marketing terms that app developers might employ. The search strategy also considered the work by Wexler et al [34] in a study related to our own. Wexler et al [34] analyzed data from pregnancy social media forums. They found that the frequency of word appearance in relation to other words revealed clusters of words that have a high probability of appearing together around certain topics. Therefore, word clusters for anxiety about pregnancy and labor were included in the search terms. Members of an established public involvement group also contributed by identifying words they would use to locate information and resources. Service users highlighted that women may also search for specific pregnancy-related aspects that cause anxiety (eg, miscarriage, giving birth) or use words to describe how they would like to feel (eg, calm, stress-free, relaxed). Again, these were included in the key search words and terms for the present review.

Apps were included in the review if they were available in English, aimed at or referred to use in pregnancy, and included advice, information, exercises, or techniques to improve symptoms of anxiety, worry, fear, or stress. Exclusion criteria were anxiety apps that did not reference pregnancy in the app information and pregnancy apps that did not reference anxiety, worry, stress, fear, or emotional or mental health.

To identify efficient and effective search terms that could be used by maternity care professionals, previously developed scripts were used to search the UK version of Google Play and the App Store. The search was conducted from January to March 2021 using the script-based approach developed by Stawarz et al [35]. The scripts were modified using alternative combinations of the suggested keywords. Each combination of keywords and the number of apps located are shown in Multimedia Appendix 1. Search results included the app name, short description, rating, and developer’s details. After script-based searching, a simple web-based keyword search of Google Play and the App Store was performed to compare the search results with those of script-based searching and to locate additional apps. Changing the country code (ie, United Kingdom, United States) did not appear to impact the search result. Changing the word order resulted in different search results on Google Play but not on the App Store. Manual screening of the app search results was completed by evaluating the app title and description against the inclusion and exclusion criteria.

Evaluation criteria that considered the findings from existing pregnancy and mental health app reviews were selected. The criteria were therapeutic or supportive content (reflective of the evidence base or clinical standards) [29,35,36], relevance for a pregnant population [26,31,37], and compliance with existing app quality measures (Multimedia Appendix 2). The following therapeutic or supportive content was evaluated against review-level evidence and clinical recommendations for perinatal and common mental health disorders [38-41]:

1. Psychoeducation: Aids in the identification of anxiety disorders and improves understanding and treatment options for anxiety.

2. Low-intensity psychological interventions including individual nonfacilitated, guided self-help or psychoeducational group. Includes written or electronic materials based on the treatment principles of cognitive behavioral therapy (CBT).

3. Mind-body interventions such as yoga or hypnotherapy.

4. Referral and signposting to services for women requiring specialist diagnosis and care.

It is important to consider whether the current evidence for an app is sufficient or relevant for a particular population [37]. Therefore, the following questions were developed by the reviewers to identify the availability of information that women could search for [42].

1. How do I know if I have anxiety?

2. How do I know the severity of my anxiety symptoms?

3. Where can I go for help for my anxiety in pregnancy?

4. How can I access specialist help for my anxiety in pregnancy?

5. What are the treatment options for anxiety during pregnancy?

6. What can I do to help my anxiety symptoms?

Based on the review by Nouri et al [18], quality criteria were selected to meet the review objectives. Subjective measures of app quality have been reported as having low interrater reliability [23]. Quality criteria were therefore selected that focused on objective measures and minimized the number of subjective responses. Efforts to reduce the subjective measures also considered end-user preference. Criteria identified by health care professionals as important may not reflect women’s needs and preferences, as different individuals may find a particular app more or less useful depending on their personal needs, circumstances, experiences, and education level [25,43]. User ratings as reported in Google Play and the App Store were also presented alongside reviewers’ evaluation scores for comparison.

Descriptive data were collected (where available) for all apps included in the review. This included the app developer and country, number of downloads, number of ratings, rating score, version number, costs, and date of the last update. Narrative description and evaluation of the highest scoring, free to download, and most popular apps were completed [29]. Apps were identified based on the app download numbers and user rating (0-5 stars) provided by Google Play and the App Store: more than 10,000 installs, a star rating of 3.5 or higher, and free to download in Google Play; and more than 10 ratings, a star rating of 3.5 or higher, and free to download in the App Store.

This resulted in the selection of 12 apps that were then evaluated by 2 independent reviewers using the criteria presented in Multimedia Appendix 2. The extent to which the app addressed the criteria was scored on a 2-point scale (0, information is absent/negative response; 1, information is present/positive response). The overall score was calculated and interpreted with caution because of the lack of validity and reliability of app quality measures [23]. Scores were used to assist in interpreting the review findings and to generate discussion on the mechanisms for selecting and recommending potentially beneficial apps (Table 2).

In total, 1391 apps were located, and 1337 (96%) apps were subsequently excluded based on the title, description, and duplication (Figure 1). A total of 39/1391 (3%) apps were included in the review (Multimedia Appendix 3).

No apps specifically targeted women with anxiety in pregnancy. Various apps focused on providing well-being support during pregnancy and included stress relief, relaxation, and mental health advice as part of a general approach to well-being in pregnancy. Of the 39 apps included in the initial review, 33 (85%) focused solely on mind-body techniques to promote relaxation, stress reduction, and psychological well-being. Mind-body techniques included relaxation, mindfulness, hypnosis, yoga, positive affirmations, and meditation. A total of 3/39 (8%) apps provided informational support, of which 1 (33%) focused on psychoeducation and 2 (67%) were multicomponent and provided information support, cognitive, or mind-body techniques. Only 8 of the 39 (21%) apps included in the review reported that health care professionals had contributed to app development (Figure 2). Only 1/39 (3%) app (Baby Buddy) provided empirical evidence on the effectiveness and acceptability of the app.

There was a small negative correlation between the reviewers’ scores and the user rating scores (r=−0.27; 12/39, 31%; P=.39) with higher user rating scores associated with lower reviewer scores.

The purpose of this review to evaluate a methodology to systematically search for and review commercially available apps was addressed by identifying useful search terms that were nonclinical and included aspirational phrases as suggested by the study service user group. The terms included “calm,” “relax,” “relief,” “cope,” and “well-being” as well as some problem-based phrases such as “stress,” “fear,” and “anxiety.” However, no clear recommendations were identified for the searching of apps to help maternity care professionals identify useful resources.

The evaluation components developed for the review provided a useful framework for maternity care professionals to assess the therapeutic or supportive content in the context of pregnancy. The quality criteria focused on more objective measures and aimed to minimize the number of subjective responses. However, the binary coding (1, information/component present; 0, information/component absent) was not amenable to capture criteria that were partly addressed by the app or where particular types of content were presented differently within the app [42,56]. The quality criteria have been revised in response to the findings and are presented in Multimedia Appendix 4. Furter studies to evaluate the reliability of the criteria are required [18].

Many of the apps that purported to reduce anxiety symptoms did not include any link to peer-reviewed literature or the evidence base. Other reviews have reported the lack of provision of evidence-based app content [28,35,36,56]. Although web-based mindfulness and CBT approaches have been reported as effective in reducing anxiety and other mental health concerns in perinatal populations [57,58], evidence-based information was not presented in the apps. The lack of clearly defined content with links to the evidence base may hinder the ability of maternity care professionals to determine the quality of the app [56]. However, this review highlighted that only 1 of the 7 (14%) most popular and highly rated mind-body apps provided any rationale for the approach or links to the evidence base.

The lack of correlation between the presence of evidence-based information or strategies and the popularity of mental health apps has been highlighted in recent reviews [35,56,59]. This suggests that features other than the provision of evidence-based information are important to and valued by women [35]. To further highlight this point, this review has demonstrated that the quality evaluation scores assigned by the review team (health care professionals and researchers) did not reflect user ratings (displayed by the app platforms). Because of the lack of information on the development of the apps, it is difficult to know whether women’s views were accessed or whether the design and content of the app reflected women’s needs.

User experience and engagement are important factors in the overall effectiveness of apps [35]. Stawarz et al [35] identified that interactive features and customization were important in improving user engagement with CBT for depression. Positivity (ability to capture positive and negative thoughts) along with privacy, security, and trust was associated with improved user experience. For this review, engagement with service users also highlighted that women may wish to use “positive” and aspirational words to describe how they would like to feel (eg, calm, stress-free, relaxed) when they search for potentially useful apps. Researchers should aim to make mobile health interventions with evidence-based treatments attractive and accessible and focus on user desirability and experience early in the design phase [59]. A combination of approaches to maximize user engagement and experience with evidence-based strategies is required to deliver potentially effective app-based strategies to support women with anxiety in pregnancy.

Pregnant women may benefit from remotely delivered interventions to help them cope with symptoms of anxiety if they are provided with web-based contact with a health care professional or peer community and may be more motivated to complete interventions that are perceived as relevant or tailored to their needs and situations [60]. Only 2 of the 39 (5%) apps included in the review provided a psychological therapeutic approach, with most apps providing mind-body techniques and exercises to support women’s general well-being throughout pregnancy, labor, and birth. Only 1/39 (3%) app was endorsed by a health care organization (Baby Buddy). Although it did not provide any therapeutic content, this app did provide information and signposting. Apps that offered coping strategies for women with symptoms of anxiety had very little information about how or when to seek help or signposting to supportive services.

The apps included in this review were promoted as either general pregnancy well-being apps (including diet, exercise, fetal growth and well-being, labor, and birth) or general relaxation apps. This review did not locate any apps that were solely focused on anxiety symptoms in pregnancy. A systematic review of perinatal web-based psychological treatments for clinical levels of maternal anxiety and depression [61] also did not locate any interventions targeted to the reduction of anxiety disorders or comorbid depression and anxiety. Although no interventions were tailored to anxiety or recruited women with a diagnosed anxiety disorder, the pooled analysis demonstrated medium and significant group differences favoring web-based interventions over control conditions for anxiety outcome measures. The authors of this previous systematic review recommend that interventions be specifically developed for this neglected area of perinatal mental health care.

The perceived reliability and trustworthiness of web-based pregnancy information have been reported to increase in women when the resource is regularly updated and when it is recommended by a health care professional [62]. Involvement of the health care provider has been reported to help individuals understand what apps can and cannot do [29]. Evaluation of app quality by health care professionals should not be a substitute for women’s preferences, usability, and other personal factors necessary for selecting an app [29]. Zelmer et al [63] sought consensus from a broad group of stakeholders on guiding principles and criteria for a framework to assess e-mental health apps. The resulting principles are similar to the criteria developed for this review across categories of security, usability, evidence base, and functionality. It would not be possible for most maternity care professionals to assess the fast-growing health apps market. Access to technologies, curated compilations, or libraries of effective apps would, however, help maternity care professionals feel more confident in recommending and signposting women to potentially beneficial resources [25,64]. Platforms such as the NHS Apps Library have started to develop such resources, inviting developers to submit apps for assessment of regulatory, clinical, security, and technological criteria [65].

For this review, potentially useful criteria for rating the quality of the content and the function of apps were suggested to support women with symptoms of anxiety in pregnancy. The criteria were based on previous research, and validity and reliability testing was not conducted nor was it within the remit of the study. The security and privacy policies of each app were not fully scrutinized, although an assessment of whether security and privacy policies were reported in the app information was included. The American Psychiatric Association has developed a framework for app evaluation [37], which begins with the assessment of compliance with safety and privacy criteria. These criteria must be met before the evaluation continues to assess benefit and efficacy, engagement, and data sharing. Simply checking for the existence (or absence) of a privacy policy will help identify questionable apps [37].

Locating potentially useful apps is not a straightforward process and requires a different approach to that used in traditional academic search. Keywords that reflect women’s search queries and that can help women and maternity care providers navigate app libraries need to be developed. App developers, publishers, and maternity care professionals should seek advice from women with lived experience of anxiety symptoms in pregnancy to locate, promote, and optimize the visibility of apps for a diverse population of pregnant women. This review did not locate any resources that provided coping strategies or therapeutic approaches for anxiety that were based on the current evidence base for the treatment of anxiety in pregnancy. The rationale, development, and testing of apps included in this review were underreported, which may hinder the ability of maternity care providers to easily locate useful, acceptable, and trustworthy resources. Potentially useful quality criteria have been presented, which require further development and testing. Maternity care professionals should be aware that features of apps other than the provision of evidence-based information and approaches are important to app users. Features such as interactivity and customization may improve user engagement, and positive framing using aspirational statements may attract women with symptoms of anxiety when they look to select an app resource. Maternity care professionals and women would benefit from access to libraries of trusted apps that have been evaluated against relevant and standardized criteria.