Digital parenting interventions for fathers of infants from conception to 12 months of age: A systematic review

Background: Digital interventions help address barriers to traditional healthcare services. Fathers play an important parenting role in their family and father involvement is beneficial for family well-being. Although digital interventions are a promising avenue to facilitate father involvement during the perinatal period, most are oriented to maternal needs and do not address the unique needs of fathers. Objective: The current systematic review described the digital interventions that exist or that are currently being developed for fathers of infants from conception to 12 months postpartum. Methods: A systematic search across Medline, PsycINFO, Cochrane Central Register of Controlled Trials, CINAHL (using Ovid), and Embase (using EBSCO) databases were used to identify 2009 articles up to June 2022, of which 39 met inclusion criteria. Articles were included if they were peer reviewed and described a digital intervention that targeted fathers of fetuses and/or infants up to 12 months. Systematic reviews, meta-analyses, and opinion pieces were excluded. Data from studies were extracted and themed using a narrative synthesis approach. Quality appraisals of articles were conducted using the mixed methods appraisal tool (MMAT). Results: Articles included 29 different interventions across 13 different countries. Most articles described interventions that were exclusively digital (76%). There were a variety of digital modalities, but interventions were most commonly designed to be delivered via website/online portal (48%). Just over half of the articles described an intervention that was designed to be delivered from pregnancy through the postpartum period (54%). Only 26% of the articles targeted fathers exclusively. A wide range of outcomes were included with 54% of articles including a primary outcome related to intervention feasibility. Of the 18 articles primarily examining efficacy outcomes, 72% reported a statistically significant intervention effect. Articles demonstrated a moderate quality level overall. Conclusions: New and expecting fathers use digital technologies, which could be used to help address father specific barriers to traditional healthcare services. However, there seem to be mixed findings regarding the feasibility/acceptability and efficacy of existing digital interventions. There is a need for more development and testing of interventions that target father-identified priorities. This review was limited by not assessing equity-oriented outcomes (e.g., race and socioeconomic status), which should also be considered in future intervention development. Clinical Trial: NA (JMIR Preprints 11/10/2022:43219) DOI: https://doi.org/10.2196/preprints.43219


Table of Contents
Digital parenting interventions for fathers of infants from conception to 12 months of age: A systematic review

Original Manuscript
COVID-19 pandemic, the social and public health protections paired with additional childcare responsibilities for families and economic uncertainty have made access to in-person services increasingly challenging. As such, complete or partial digital delivery of interventions has become increasingly beneficial during this time [7,8].
The pandemic has been particularly burdensome for individuals in the transition to parenthood as it has unexpectedly altered the standard approaches to pregnancy and childbirth care, with many countries restricting access for fathers (i.e., individuals who identify as male primary caregivers) and parenting partners (i.e., any individual who supports the birthing parent) to attend medical appointments prior to and following the birth of their children [9]. Visitor restriction policies in hospitals were also found to be disproportionately harmful on racially diverse communities [10].
Although digital interventions exist for parents, they are often oriented towards mothers (i.e., birthing parent or an individual who identifies as a female primary caregiver) rather than fathers and parenting partners/co-parents [11,12], who have historically been underrepresented and excluded in parenting research [13]. This is problematic as the World Health Organization (WHO) has identified the importance of exploring effective strategies to increase the involvement of fathers in the process of pregnancy and childbirth in order to support mothers and their children, and there has been increasing recognition of the benefits of co-parenting [13,14].
Although all parenting partners and co-parents play an important parenting role in the family, fathers are one group of parenting partners whose roles have been increasingly recognized in existing literature. For instance, past research has shown that father involvement in care during the perinatal period (i.e., from conception to one year following birth) and father's access to knowledge about the transition to parenthood are important for perinatal mental health, provision of support, and better adjustments to parenthood [6]. New and expectant fathers are at risk for psychological distress in the perinatal period [e.g., depression ; 15], and these difficulties are associated with maternal postpartum depression [16,17], less and poorer quality of paternal involvement with their children's development [18,19], and unhealthy lifestyle behaviours [e.g., substance use ; 20]. However, increased father involvement is associated with lower levels of paternal depressive symptoms [21], better prenatal maternal health behaviours, including decreased smoking and attaining prenatal care [22], better child neurodevelopment [23], early breastfeeding practices [24], and maternal and infant/ toddler sleep [25,26]. In addition to mental health, child development, and infant feeding, sleep has been identified as a top priority among expectant parents and caregivers of children up to age 24 months [27].
Parents often seek both information and support on the Internet [28,29] and meta-analyses have shown that digital programs designed for parents are effective in improving parenting skills and child outcomes [30][31][32]. However, despite the significant benefits to preparing fathers for parenthood [22,25,26], most online parenting resources are oriented toward maternal needs [11]. Resources targeted primarily towards mothers, without being adapted for fathers, can be ineffective as fathers' needs can differ from those of mothers during the transition to parenthood [33,34]. Research, which aimed to investigate the needs of parents during the transition to parenthood, found that fathers tend to report a lack of or inaccessible parenting information/supports specifically for fathers and report feelings of frustration about a lack of involvement in the antenatal period [35,36]. Fathers have identified that inflexible working practices, gaps in service, sleep deprivation, a lack of infant care skills, and feeling excluded by health professionals as specific barriers to receiving health information during the transition to parenthood [6,37].
Technology is widely used for new and expecting fathers as a source of parenting information, with fathers showing a strong interest in using Internet-delivered strategies for mental health and parenting supports during the transition to fatherhood [38,39]. Although traditional health services, monitoring, and psychoeducation provided by healthcare clinicians are often key aspects of prenatal care [40], many fathers turn to digital technology to learn from the parenting experiences of others. For instance, fathers report enjoying and benefiting from listening to the stories of other fathers who have gone through similar experiences [41]. Online father support groups are becoming increasingly used by fathers, and as such, these are an important resource [39,42]. Although these types of informal support groups are valuable, evidence-based interventions are crucial. Fathers have expressed the need and desire for access to relevant, accurate, and up-to-date information on infant care, challenges associated with new parenthood, as well as the availability of support services [6,43]. Specifically, first-time fathers have described a need for more information on the demands of fatherhood shortly after birth as well as how to recognize when to reach out for mental health supports [6]. In one video-modeled play intervention, fathers supported that 4 months postpartum was the right time to start the program with some expressing interest in a higher frequency of home visits (i.e., monthly) and to have the intervention extended to a one-year duration [43].
Father-targeted digital interventions are a promising avenue to promote the health of families.
The perinatal period is a critical and time-sensitive time, whereby more paternal involvement and less maternal parenting stress can positively influence infant development [44]. Digital interventions offer a unique opportunity to re-examine how interventions can be more inclusive of fathers throughout the perinatal period in order to promote and maximize the benefits of father involvement.
Therefore, this systematic review aimed to describe the digital interventions that exist or currently being developed for fathers of infants -from conception to 12 months post-partum to provide the foundation for future development, testing, and implementation of digital interventions for fathers. In recognition of the unique roles and experiences of fathers, this review is focused on the term "fathers", rather than parenting partners.

Methods
This systematic review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [45]. The inclusion criteria for papers were (a) a peer reviewed article or protocol, (b) described an intervention that targeted fathers of fetuses and infants up to age 12 months, (c) any outcome, (d) any infant population (e.g., infants born term and pre-term, those in hospital or community), and (e)  [54,55]. Data on study design, study aim, sample, the intervention (including type of digital modalities), study outcomes (e.g., infant feeding, parenting knowledge, parenting self-efficacy, child outcomes, parental mental health), and results for outcomes were extracted. Statistically significant intervention effects were determined using p-values (< .05). Favourability of interventions was also assessed and determined based on the reported acceptability/satisfaction/usability of the intervention or the rate of participant adherence/engagement. Interventions were considered favourable if there was an adherence or engagement rate greater than 60% or if more than 60% of participants identified satisfaction, acceptability, and/or usability of the intervention. Two researchers independently reviewed all abstracts and full texts and the additional authors (KB and LTM; PhD) reviewed and resolved all conflicts that arose. Prior to extraction, protocol papers and trial registrations underwent a forward reference review by JJ and JK to identify whether there was a subsequent published article following from the protocol paper or trial registration. Of the 39 studies included, five were added following the forward reference review (in lieu of the protocol or clinical trial registration that preceded it).
Pilot extraction was performed for reliability and then extraction was completed independently. Articles were described and themed using a narrative approach. This allowed the researchers to summarize a wide range of interventions and diverse study outcomes in a systematic way. Quality appraisals of each included article were conducted by the research team (BX, JJ, and includes two screening questions (i.e., are there clear research questions and does the data allow for addressing the research question) and five quality criteria for each type of study design (i.e., qualitative, quantitative RCT, quantitative non-randomized, quantitative descriptive, and mixed methods). The questions in each domain are answered by 'yes', 'no', or 'cannot tell'. The MMAT has been shown to be a reliable tool for reviews that incorporate diverse study designs [57] and it provides overall methodological scores calculated as a percentage, from 0 (poor quality) and 100 (high quality). As in other reviews, scores were calculated as percentages, based on the number of criteria met [58,59]. Mixed methods studies included both qualitative and the appropriate quantitative scores in their final MMAT score calculation.

Results
Of the 39 peer-reviewed articles included, one described a protocol only, one described the development of the intervention as well as a study protocol, nine described the development of the intervention only (i.e., the intervention development was in progress), and 28 tested the usability, satisfaction, or effect of an intervention. Articles included 29 different interventions that were developed or tested in Canada, Brazil, USA, Finland, China, Australia, Iran, Nigeria, Singapore, Turkey, Korea, Denmark, and Netherlands between 2003 and 2022. The most common study designs were randomized controlled trials (n = 14, 36%; two of which were proposed studies), followed by quantitative non-randomized (n = 7, 18%). See Table 2 for more detailed descriptions of study designs.
Nine interventions clearly described a guiding theory (e.g., self-efficacy theory, social cognitive theory) underlying intervention development or testing. Of the 29 different interventions, fathers appeared to have been involved in co-designing less than half of them (n = 10; 33%). Codesign techniques included strategies such as father involvement in focus groups and interviews during app development (i.e., Milk Man app) [60][61][62], surveys of fathers about their information needs and factors associated with the decision to visit a father-focused website [38], and the incorporation of feedback from fathers during text message development (i.e., SMS4dads) [63].
Most interventions were exclusively digital (n = 22, 76%), meaning they were "stand-alone" and did not have a component that depended upon an in-person interaction with a human provider.
Over half (22/39; 56%) of the articles described an intervention that targeted couples together (e.g., both mothers and fathers/co-parents). Only 10 (26%) targeted fathers exclusively and the remaining seven articles included both mothers and/or fathers. Just over half of the articles described an intervention that was designed to be delivered from pregnancy through postpartum period (n = 21/39), while 33% (n = 13) targeted the postpartum period only, and 13% (n = 5) targeted the prenatal period, only.
In terms of primary study outcomes that the intervention was evaluated for, about half (21/39) of the articles had a primary outcome related to acceptability, usability, or satisfaction with the intervention. Of these 21 studies, 11 studies were examined for perceived favourability, with 8 being considered as favourable by the review team and 3 articles being perceived to have non-favourable outcomes (see Table 2 for outcome summaries). Articles also evaluated intervention effects on outcomes such as coping, parent satisfaction, and/or parenting self-efficacy (n = 12), co-parenting (n = 6), paternal mental well-being (n = 6), parent-child relationship (n = 5), infant feeding or breastfeeding (n = 4), injury prevention (smoking cessation; n = 1), and infant physical health (weight gain; n = 1). Of the 18 articles primarily examining efficacy outcomes, 13 reported a statistically significant intervention effect. Statistically significant intervention effects were reported for father-child attachment/interaction [66][67][68], knowledge and attitudes about participation in perinatal care [69], smoking cessation and mothers second-hand smoking exposure [70], parenting self-efficacy and/or satisfaction [71][72][73], breastfeeding self-efficacy, knowledge, and infant feeding attitudes [74,75], parental depression, and child sadness [76], and parental anxiety, depression, and quality of life [77].
The majority of included studies (n = 31; 79%) used a convenience sample (i.e., from clinics or health services, either self-selected or during a certain time period, or a general convenience sample). In terms of study quality, MMAT scores ranged from 20% and 100%, with only 15/36 articles that met 80% or more of the MMAT criteria. In total, 9 articles met all domain criteria, 6 met 80% of criteria, 10 met 60% criteria, 7 met 40%-50% of criteria, and 4 met 20% of criteria. Three articles could not be appraised as they described protocols or processes [62,78,79]. Articles examining primary outcomes related to parent-child relationships, father mental health/well-being, injury prevention, and co-parenting/partner-support appeared to have slightly higher MMAT scores, all scoring ≥ 60%. Articles examining primary outcomes related to parenting coping/satisfaction/selfefficacy, NICU care, and parenting involvement appeared to have lower MMAT scores, all scoring ≤ 60%. Articles examining primary outcomes related to infant feeding/breastfeeding and parenting skills and knowledge had a wider range in quality. An information package on infant health/development and parenting was mailed to expectant fathers. Three text-only emails with useful websites and information were also distributed to fathers based on their topics of interest. Online intervention based on self-efficacy theory [82] with access to an information database, an online peer discussion forum with a question and answer service provided by specially-trained nurses and midwives. The online database contained information about everyday parent-child interactions, how to be sensitive to infants' cues and needs, and how to respond to them in a growth-fostering way. Parents can use these services based on their individual needs in addition to standard care (guidance given at the hospital after childbirth and through to 1-year postpartum). Furthermore, in addition to the discussion forum, parents can individually contact a trained registered nurse or midwife for 2-week postpartum and ask anonymous questions online. The video self-modeling with feedback intervention was based on bioecological theory [83] and self-modelling theory [84]. The video self-modelling with feedback was delivered during in-person home visits with a booster dose being provided via fathers being encouraged to watch the video interaction through a web-based platform. The intervention consisted of video-recording of a structured play interaction between the father and their 4-month infant. Following this, the father and home-visitor reviewed the video, with the visitor indicating behaviors that fostered development, reinforcing the father's strengths, and making suggestions X X 12 for improvement. The structured play and feedback took 15 -20 minutes, after which the father was provided with a handout addressing infant cues. For the twovisit group, play and feedback were repeated during a home-visit when infants were 6 months old and handouts about the teaching loop and tips for language stimulation were provided. In the four-visit intervention group, the additional two visits occurred when infants were 5 and 7 months old, and handouts about promoting language development were provided. (Rhoads et al., 2015) [85] This intervention consisted of online, password-protected access to web cameras that allowed parents to view their hospitalized neonates in real-time, at any time of day or night. The NICU-2-Home mobile application was designed using Bandura's Self-Efficacy theory [86] to support parents of Very Low Birth Weight (VLBW) infants. It consists of the four following features: (1) Passport-2-Home-a self-guided discharge checklist; (2)  The Milk Man mobile application was designed and developed using social cognitive theory [87] to educate new and expectant fathers on breastfeeding, infant feeding, early parenting, and being a supportive partner. Components of the app included push notifications, a forum for fathers to have conversations with one another, an information library, and gamification. Push notifications alerted users to new discussion topics, which were posted twice a week on the app. These posts allowed users to connect with each other through a series of topics initiated by the app administration. Users could interact by adding comments, upvoting, or responding to polls. An information library was also included and provided external website links. For gamification, the app used leaderboards, badges, and points to encourage engagement with both the discussion topics and information library. Fathers were grouped together based on the stage of their partner's pregnancy. SMS4Dads is an automated program that sends text messages to fathers across prenatal and postpartum periods. Messages consist of maximum 160 characters, and provided information on physical health, mental health, supporting mothers through pregnancy, and building relationship with their child. Along with these informative messages, website links to useful resources in parenting and self-care are also included. Text message content and schedule were tailored to gestational X X* X* X The eHealth breastfeeding co-parenting resource provided information about breastfeeding and co-parenting to pregnant or new mothers and their partners. The content was divided into seven main topics that was delivered through an online website. Topics covered (1) the benefits of breastfeeding, (2) how to breastfeed, and (3) expectations for breastfeeding during the early days. Another topic was oriented towards fathers, partners, and co-parents and provided information on supporting mom, working as a team, involvement with breastfed children, effective communication and problem solving (4). The other topics touched on common concerns around breastfeeding (5), and various areas of everyday living (6 and 7). Information for all seven topics was presented to users through a combination of text, quizzes, games, videos, and links to additional online resources. Users were able to select topics at their convenience. X X (Pilkington et al., 2017) [95] Partners to Parents was an online intervention that aimed to prevent perinatal depression and anxiety by facilitating partner support. This was done by providing information on the following topics via a website: potential changes during parenthood, effective communication strategies, intimacy, instrumental support, social support, establishing boundaries, self-care, depression and anxiety symptoms, and accessing professional support. For the purpose of the study, participants were asked to use the website for a single thirty-minute session. The needs assessment in this article will help to guide the development of the Healthydads.ca. Healthydads.ca will be a website with the goal to enhance mental health and healthy behaviours in expectant fathers that can be easily accessed for resources and help on emotional wellness and pregnancy and parenting information. The intervention consisted of slideshows presented on a website that detailed weekby-week fetal development. One slideshow used common fruits and vegetables as visuals to illustrate fetal growth (similar to widely downloaded pregnancy applications and webpages) and another slideshow used common sports objects to illustrate week-by-week growth. The slideshows were delivered via website application where participants could access a module's content by clicking on the illustrative icon, title, or description on the home page. In the online version of the Family Foundations intervention couples received five prenatal and three postnatal online modules focused on helping couples consider and adjust expectations, adopt a realistic vision and prepare for the strains of parenthood, and develop skills related to supportive, cohesive parenting communication, and problem-solving. In between the modules, written and communication exercises were presented for couples to complete. After starting the program, if the couple stopped engaging in the program for more than 10 days, email reminders were sent encouraging them to continue. The development of the intervention was partly based on the innovative group discussion approach of supporting couples at the transition to parenthood developed by Philip Cowan and Carolyn Cowan.
The PRENACEL program is a text-messaging intervention that provided information about prenatal care to partners of pregnant women and encouraged partner involvement during pregnancy. The intervention included a total of 62 text messages delivered during 5 -42 weeks gestation and the immediate postpartum. Partners received one to two text messages each week, with the content relating to the pregnant woman's gestational age. The messages were adapted from the Mobile Alliance for Maternal Action (MAMA). This psychoeducational intervention aimed to prevent postpartum parenting stress, and to enhance parental well-being and caregiving quality. Delivery of the intervention consisted of an information booklet, an online video, a home visit, and a telephone call. The booklet contained four chapters outlining the following topics:

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(1) infant's needs and signals of distress; (2) patterns of crying and soothing techniques; (3) hunger signals and feeding arrangements; and (4) sleeping patterns and sleeping arrangements. The online video illustrated these topics and engaged participants in thinking about how they can implement the information in their own lives, which took 15 -20 minutes. The home visit was then used to discuss the material further and respond to any questions from parents. A phone-call check-in at 4-weeks postpartum was used to ask parents how they were doing and discuss any challenges. (Firouzan et al., 2020) [69] There were two intervention groups. In one intervention, fathers received in-person training via speech, displaying images, sharing of experiences, and Q&A, over two, 2-hour sessions. They then received 3-4 text messages weekly, up to 3 months about pregnancy, partner's role in perinatal care, relationship with the fetus and the mother, and other preparatory information. Training content included information about changes in women's body during pregnancy, common complaints during pregnancy, and the role of men in women's adaption. It also included information about men's participatory role in perinatal care, including the father's relationship with the fetus and the mother, preparation for childbirth and fatherhood, how to deal with danger signs during pregnancy, the role of men in delivery process, social support during pregnancy, childbirth and postpartum. It also addressed barriers to men's participation during pregnancy, childbirth, and postpartum and remedies. The other intervention group received the same information via compact disk. X (Marcell et al., 2021) [78] This protocol describes the Text4FATHER text-messaging program, which is informed by the Integrated Behavioral Model [100], and aims to provide fathers with guidance on infant, partner, and personal well-being support. This will be done through the delivery of twice-weekly texts for seven months that will be tailored to the mother's gestational age, infant age after birth, and father's resident status. Of the total 71 texts, 24 will include weblinks that share additional information, infographics, and videos. Couples were part of WhatsApp parenting group where they received education modules in the form of written texts or voice recordings. These education modules provide information regarding issues such as the baby's biopsychosocial care (according to the baby's developmental level) and assessment, parent-infant communication, etc. Each voice recording message was approximately 5 to 10 minutes long. Couples also could ask questions and engage in an online consultancy with a specialist psychiatric nurse, a specialist gynecology nurse, and a specialist pediatric nurse, at any time during the day in their WhatsApp group. In these groups, they also shared their experiences, problems, and solution suggestions about the postpartum period and baby care.
This intervention was delivered in a virtual format and provided fathers with information on 1) pregnancy diet, 2) mental health during pregnancy, 3) planning X X X 16 2021) [68] for delivery and selecting the type of delivery, and 4) and neonatal care. Educational contents were uploaded to the social media app (Telegram) and were delivered to participants prenatally at four time points (24-28 weeks, 28-30 weeks, 32-33 weeks, and at 37 weeks). (Kavanagh et al., 2021) [102] Participants were randomized to either the Baby Steps Wellbeing (treatment) or the Baby Care web program (active control group) interventions. Both arms received four self-paced online informational modules with information on 1) getting prepared for birth, 2) infant feeding, 3) infant sleep, and 4) infant soothing as well as a list of telephone support or digital services. The Baby Steps Wellbeing group also received five additional online modules on: self-care, their romantic relationship, baby interaction, role adjustment, and a module created especially for fathers as well as a space for goal-setting, a web-based scrapbook option, and quiz questions about baby care. Both groups received automated SMS texts received two, four, seven, and ten weeks after condition allocation reminding parents to log into the program. The text messages to parents in the Baby Steps Wellbeing condition also included recommendations to review their goals. The Supportive Parenting App (SPA) was an online intervention delivered through a mobile application. It was developed based on social cognitive theory [104,105] and attachment theory [106]. The main features of the intervention included knowledge-based content, informational videos and audio clips, an online discussion forum, group and private chats with peer volunteers, expert advice from a maternity unit nurse or midwife through an online forum, and individualized push notifications. Information was provided on the topics of pregnancy, childbirth, baby care, maternal care, family, and parenthood. The intervention included 42 knowledge-based articles and 27 inspirational and demonstration videos. Push notifications were sent on a weekly basis during pregnancy, daily basis during one month postpartum, and biweekly following that until 6 months after childbirth. In the Telematic Family-Centered Care (T-FCC) Group parents were not able to access the NICU but were allowed to see their newborns via smartphone video calls. Video calls occurred while newborns were feeding, sleeping, or during procedures. During this time, parents were updated on the process of care and parents were provided support from a psychologist on the call. Parents were also able to receive telephone updates on the clinical status of their newborns. Couples with an infant with congenital heart disease (CHD) received health education and care guidance via WeChat. The intervention included two parts -the education module, and the question-and-answer module. The education module included related knowledge on coronary heart disease, postoperative care, family care, feeding and management of complications. Parents could view the module and learn at any time that was convenient for them. The question-and-answer module included one medical staff member that available via WeChat to address parents' problems and guide the family members to discuss and share their care experiences.  Note. Articles are grouped by primary outcomes. However, many papers include outcomes that fit in various categories. Note. There were mothers included in some studies but only reporting on father/partner sample size when provided. Note. Bold outcomes of interest were found to be statistically significant. Finding notes provide additional detail when applicable and informative. †Mother and father dyads combined in reporting. *Favourable rating of intervention usefulness, satisfaction, and uptake based on results. / x Not favourable rating of intervention usefulness, satisfaction, and uptake based on results.
[] Sample size reported in square brackets refers to planned sample size for proposed future study.

Discussion
To our knowledge, this is the first systematic review to describe studies of digital interventions for fathers in the perinatal period. During the search, 39 articles were included that described 29 different interventions either under development or being tested across 13 different countries. There was a variety of digital components included in these interventions, classified into seven distinct categories: online programs and websites, mobile apps, SMS, digital videos, email, social media, and videoconferencing.
Interventions targeted a wide range of outcomes including broader parenting outcomes (e.g., self-efficacy, satisfaction, parent-child interaction, infant knowledge), father well-being, as well as more specific outcomes relating to breastfeeding and smoking cessation. However, most articles were focused on evaluating the feasibility, acceptability, and usability of the digital intervention or components of the intervention being developed. The emphasis on evaluating feasibility, acceptability, and usability highlights the growing interest in research on digital interventions for fathers of infants but also indicates the need for more rigorous research designs to determine if such interventions can result in improved health-related outcomes. In regard to feasibility and acceptability outcomes, of the 21 articles that examined these outcomes, just over half (n = 12) provided basic descriptive results with no clear criteria for determining adequate feasibility and/or acceptability.
The research team was surprised to discover that, despite being a common concern of new parents, there were no digital interventions that primarily targeted fathers' sleep quality and quantity as study outcomes. This is consistent with a recent review highlighting that the role of fathers/other caretakers on infant sleep has been largely neglected [107]. This is problematic as infant sleep problems are inversely associated with fathers' general health [108]. Father 34 involvement in infant care has been shown to be important for infant sleep [109] and expecting fathers have identified wanting information related to managing sleep improvements [38]. Of the included articles, only one intervention examined secondary father's sleep outcomes [99] although there were no significant effects of this intervention on sleep outcomes. Another intervention included a module on sleep and explored parenting self-efficacy items related to infant sleep, however, this also was non-significant [102]. Furthermore, one article that described intervention development examined levels of father's self-efficacy related to infant sleep [81] and a protocol paper included safe sleep as a proposed secondary outcome [78].
Few studies included in this review measured behavioural change outcomes among fathers. Although feasibility and father beliefs and knowledge about infant care are important, these may not necessarily lead to observable behaviour change and parenting strategies, which are important for conferring secondary benefits for children and families [110,111]. For instance, Venegas and colleagues found that although individuals in the intervention group reported intentions to use or advocate for the use of pain-management strategies, there was no significant group differences in the actual use of pain-management strategies [97]. Therefore, future research should test interventions that target modifiable behavioural factors.
In contrast to the current state of the digital intervention literature for mothers in the perinatal period, the digital intervention research for fathers lags behind, particularly with a lack of evidence regarding their effectiveness. For mothers, a systematic review suggests the effectiveness of digital tools in maternal health education, with a steady increase of studies in this area, particularly in the prenatal period, in the last decade [112]. Digital interventions have been shown to be effective for improving postpartum depression [113,114], for treating insomnia in pregnancy [115], and for preventing alcohol consumption [116]. There are mixed 35 findings regarding their effectiveness for other mental health outcomes (e.g., anxiety), psychosocial outcomes including perceived stress, coping, and self-efficacy [113,117,118], and physical health outcomes [119]. However, past reviews and meta-analyses suggest promising evidence, including cost-effectiveness [120], for the use of digital interventions for mothers in the perinatal period [118]. Whereas the focus of the literature on maternal-focused digital interventions seems to be on efficacy testing and implementation, digital interventions for fathers appears to still be in its infancy with more work being focused on intervention development and the feasibility and acceptability of these novel interventions. Given the effectiveness of digital interventions for mothers, pursuing this work with fathers is likely a worthwhile and promising avenue.
There may be continued challenges related to father recruitment and engagement in digital intervention research studies during the perinatal period. Only ten of the included articles (3 of which tested the SMS4Dads intervention) [88,89,91] specifically recruited fathers while the other studies recruited only couples, or both. Given the unique needs of fathers and their reported barriers to traditional health services [6,33,34,37], along with the potential of digital interventions to overcome these barriers, development of digital interventions could be conducted specifically with fathers in mind. For instance, research can incorporate the use of patient advisory boards to ensure that the needs of patients are being met in a comprehensive way [e.g., 121]. Past research has found couple-based interventions to be advantageous for parents, as they can promote partner support of father involvement [13,122]. Although many of the current interventions are aligned with this, as they target partners, future research could explore whether the effectiveness of interventions for fathers differs as a function of whether it is delivered solely to fathers or both partners simultaneously, specifically in a digital context.

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Based on the MMAT appraisal, the articles included in the current review demonstrated a range of quality levels (20% -100%) with a moderate quality level overall. Most articles also used a convenience sample. This can lead to biases in intervention testing as it limits the ability to test whether these digital interventions are inclusive of and accessible to the general population. Parents who are ethnically diverse and in lower socioeconomic groups tend to experience higher levels of parenting stress and conflict [123]. As such, future studies should ensure interventions are being developed and tested in representative and generalizable samples.

Future Directions
There appears to be a growing interest in the feasibility and acceptability of digital interventions for fathers of infants. However, there is a need for more efficacy trial testing that examine outcomes such as sleep and father mental health -challenges that have been expressed by new and expecting fathers [38,124]. Furthermore, this review is limited by not assessing equity-oriented outcomes (e.g., race and socioeconomic status), which should be considered in future intervention development. Interventions should aim to be inclusive for all fathers and target father-identified priorities through direct partnerships with diverse patient populations [125]. Importantly, a key advantage of digital health interventions is their potential for increased accessibility and scalability with relatively low costs. Although more interventions have been/are being developed to target broad parenting abilities (e.g., co-parenting, parenting self-efficacy) and more specific topics (e.g., smoking cessation and infant feeding), future interventions should aim to target less explored areas such as paternal sleep and mental health, which have been 37 identified as a patient prioritized research gap from conception to age 24 months [126].

Conclusion
Leveraging digital technologies to develop and deliver interventions could help to address father specific barriers to traditional healthcare services. However, there seems to be mixed findings regarding the feasibility/acceptability and efficacy of the existing digital interventions and the interventions under development. Future research on digital intervention development and testing are needed and strategies for father reach should be explored.
Researchers may consider incorporating patient advisory boards to ensure that interventions are addressing the specific needs of new and expecting fathers.