Prenatal Attachment and Perinatal Depression: A Systematic Review

Pregnancy is a period of complex bio-psychological changes, during which the development of an attachment bond to the fetus takes on a central role. Depressive symptoms are common during this period. Both symptoms of depression and low levels of prenatal attachment are related to negative outcomes in caregivers and infants. Following the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement, this systematic review analyzes and systematizes 41 studies concerning the association between prenatal attachment and perinatal depression. The majority of the studies reported a significant association between the two. Specifically, prenatal depressive symptoms were found to be negatively associated with prenatal attachment. Furthermore, lower levels of prenatal attachment were related to higher postnatal depressive symptoms, although fewer studies assessed this association. While these results were found across different populations, conflicting findings emerged, suggesting they should be interpreted with caution, particularly in male samples and in non-normative pregnancies (e.g., high-risk pregnancies, medically assisted pregnancies, and pregnancies with previous perinatal losses). These results are clinically important for the perinatal screening process and for implementing preventive and treatment programs. However, future studies are needed to further confirm and generalize these results.


Introduction
Pregnancy represents a psychosomatic event that is at the same time enriching, gratifying, and stressful due to physical, physiological, and psychological changes [1,2]. During gestation, caregivers are required to reorganize their internal experience and adjust their new parental responsibilities, roles, and relationships to old ones [3,4].
In particular, during the first trimester of pregnancy, expectant parents must constantly adapt to new mental representations of themselves and of the future baby, which can create a high level of ambivalence and a sense of disorientation [5][6][7]. During this period, the father may evidence a higher level of preoccupation because his experience is less tangible than the mother's [8]. The mother plays a key role in the assumption of his paternal identity, mediating and supporting the father's experience [9]. During the second trimester, parents tend to accept this new physical and psychological situation [10]. Additionally, the father begins to become an active participant instead of just a bystander [4,6].
From the 18th to the 25th week of gestation, perceiving fetal movement enables the mother to differentiate between herself and the fetus and to consider him or her as an agent with needs, forms of communication, and intentionality. During this period, prenatal attachment starts to develop [3,10,11]. While the attachment relationship is based on a bidirectional interaction between primary caregivers and the infant that is established in the first years after childbirth with the aim to provide security, have emerged. Clarifying the relation between these two variables could be clinically important for the screening process during the perinatal period and for implementing preventive and treatment programs that can address both conditions. Furthermore, exploring this association whilst focusing on different populations (i.e., women, men, and parents undergoing non-normative pregnancies) could be useful for providing individualized treatments.

Data Source and Search Strategy
The current systematic review followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement [82]. Two independent reviewers searched through EBSCO databases (CINAHL Complete, Family Studies Abstracts, Mental Measurements Yearbook, PsycARTICLES, PsycINFO, Social Sciences Abstracts-H.W. Wilson, Sociology Source Ultimate, Violence & Abuse Abstracts), PubMed, Scopus, and Web of Science (All Databases). They analyzed titles, abstracts, and full texts to find eligible studies published from the beginning of the research databases to November 2019. The following keywords were used ("prenatal attachment" OR "maternal fetal attachment" OR "parental fetal attachment" OR "paternal fetal attachment" OR "pre-partum attachment" OR "antenatal attachment" OR "prenatal bonding" OR "maternal fetal bonding" OR "parental fetal bonding" OR "paternal fetal bonding" OR "pre-partum bonding" OR "antenatal bonding") AND ("depression").

Inclusion and Exclusion Criteria
The inclusion criteria for this review were: (1) an assessment of the association between prenatal attachment and perinatal depression, (2) original research paper, (3) published in English. Papers that did not meet these inclusion criteria were excluded. Furthermore, reviews, systematic reviews, and meta-analysis were excluded. No time limit for paper searching was imposed; all the articles published from the beginning of the research database up to November 2019 were considered.

Study Selection and Data Extraction
An initial search of EBSCO yielded 262 results; 40 were selected for full-text review. A second search on PubMed produced 92 results, 30 of which were selected. Scopus yielded 1473 papers, 55 of which were selected. Web of Science provided 214 articles, 51 of which were selected. After removing duplicates, 80 articles in total were obtained. The full texts were analyzed, reducing the number of eligible articles to 64. Of these, 45 studies matched the inclusion and exclusion criteria and were thus included in the current systematic review ( Figure 1). Any disagreements between the two independent reviewers (LR and MG) during the study selection and data extraction processes were discussed with the third reviewer (TT), and a unanimous agreement was reached.

Results
The included studies were mainly conducted in the US (10 papers) [80,[84][85][86][87][88][89][90][91][92] and in Europe (nine papers in Italy [93][94][95][96][97][98][99][100][101], four in Sweden [76,[102][103][104], two in Germany [105,106], one in the Netherlands [22], one in France [107], one in England [79], one in Belgium [108], and one in Portugal [75]). Four studies were carried out in Japan [81,[109][110][111], two in Australia [112,113], two in Iran [74,114], two in Turkey [78,115], one in India [116], one in Israel [117], one in Chile [118], one in Brazil [119], and one in Korea [120] (Figure 2). All the articles were published between 1988 and 2019 ( Figure  3). From 2011 onward, authors' interest in the relationship between prenatal attachment and depression both during pregnancy and during the first postnatal period increased [74,75,93,94,100,118]. Interestingly, from 2009 onward, an increased number of studies focused on the relationship between prenatal attachment and perinatal depression in fathers in order to facilitate individualized treatments [22,79,103]. Irrespective of the considered time frame, conflicting results emerged regarding the association between the two variables examined in the current systematic review. Nonetheless, it is noteworthy that most of the studies included that failed to find significant results were conducted between 1988 and 2009. During this period, the majority of the studies that explored the association between prenatal attachment and perinatal depression did not find significant results. Instead, between 2010 and 2019 almost three-quarters of the analyzed studies identified results that supported a relationship between the two variables.

Quality Assessment
The quality assessment of the included papers has been conducted by two independent coders using a 15-items quality rating list [83]. Each item can be scored as 1 (yes) or 0 (no/unclear). Any disagreements were discussed to reach a unanimous consensus. The final score of each article has been reported in the last column of Table 1.   In both groups maternal antenatal attachment did not correlate with prenatal depression. In RP group, but not in PP group, paternal antenatal attachment was negatively correlated with maternal prenatal depression.  A negative association was found between maternal prenatal attachment and postnatal depression.

Results
The included studies were mainly conducted in the US (10 papers) [80,[84][85][86][87][88][89][90][91][92] and in Europe (nine papers in Italy [93][94][95][96][97][98][99][100][101], four in Sweden [76,[102][103][104], two in Germany [105,106], one in the Netherlands [22], one in France [107], one in England [79], one in Belgium [108], and one in Portugal [75]). Four studies were carried out in Japan [81,[109][110][111], two in Australia [112,113], two in Iran [74,114], two in Turkey [78,115], one in India [116], one in Israel [117], one in Chile [118], one in Brazil [119], and one in Korea [120] (Figure 2). All the articles were published between 1988 and 2019 ( Figure 3). From 2011 onward, authors' interest in the relationship between prenatal attachment and depression both during pregnancy and during the first postnatal period increased [74,75,93,94,100,118]. Interestingly, from 2009 onward, an increased number of studies focused on the relationship between prenatal attachment and perinatal depression in fathers in order to facilitate individualized treatments [22,79,103]. Irrespective of the considered time frame, conflicting results emerged regarding the association between the two variables examined in the current systematic review. Nonetheless, it is noteworthy that most of the studies included that failed to find significant results were conducted between 1988 and 2009. During this period, the majority of the studies that explored the association between prenatal attachment and perinatal depression did not find significant results. Instead, between 2010 and 2019 almost three-quarters of the analyzed studies identified results that supported a relationship between the two variables.

Main Findings
Considering the 45 studies included in the current review, 31 found a negative association between prenatal attachment and perinatal depression [

Main Findings
Considering the 45 studies included in the current review, 31 found a negative association between prenatal attachment and perinatal depression [
Six of the ten studies that assessed prenatal attachment between the first and the second or the third trimester of pregnancy found a significant association with perinatal depression: six studies identified a negative association between prenatal attachment and prenatal depression [81,89,108,110,111,118] and three underlined a significant association between prenatal attachment and postnatal depression [81,110,111]. In contrast, the study of Barone, et al. [94] observed a positive association between prenatal depression and the "fantasy" and "maternal sensitivity to the fetus" factors of the PAI. The remaining three articles did not demonstrate an association between prenatal attachment and prenatal depression [79,88,109]. The only one study that administered prenatal attachment tool in the first trimester of pregnancy confirmed the association between prenatal attachment and postpartum depression [99]. All five studies that did not specify the time at which they evaluated prenatal attachment identified a significant association with prenatal depressive symptoms [75,107,114,119,120].

Sociodemographic Variables
Of the 41 articles that focused on pregnant women [74][75][76]78 [74,81,95,99,101,105,110,111,116,117]. Three articles observed a positive association between prenatal depression and some dimensions of prenatal attachment [94,102,106]. These latter findings emerged within homogeneous samples of women aged 18 or older. Considering this population, 19 studies found a significant negative association between prenatal attachment and prenatal depression [75,81,84,89,90,92,98,102,[104][105][106][107][108]110,111,[114][115][116][117], while nine articles identified a negative association between prenatal attachment and postpartum depression [81,95,99,101,105,110,111,116,117]. However, considering similar groups of participants, ten studies did not support the association between prenatal attachment and prenatal depression [76,80,87,88,93,96,97,100,109,113], and one study did not confirm the relation between prenatal attachment and postpartum depression [85]. Prenatal attachment was negatively associated with perinatal depression in four of the five studies that considered women aged 14 or older: three articles found an association between prenatal attachment and prenatal depression [91,118,119] and one article found an association between prenatal attachment and postpartum depression [74]. The association between prenatal attachment and prenatal depression was not confirmed in the study by Ulu, et al. [78].
Regarding socioeconomic characteristics, as stated before the most of the studies reported that the majority of their female participants were highly educated or had a college degree, had full-time employment, had a medium economic income, were involved in a stable relationship, and did not belong to an ethnic minority. Within this population, 22 articles reported a significant association between prenatal attachment and perinatal depression: 17 articles found a negative relation between prenatal attachment and prenatal depression [75,81,84,86,98,102,[104][105][106]108,[110][111][112]114,115,117,118] and nine articles identified a negative association between prenatal attachment and postnatal depression [74,81,95,99,101,105,110,111,117]. In contrast, three studies observed a positive relation between antenatal depression and some dimension of prenatal attachment [94,102,106]. Ten studies did not find significant results: nine studies regarding the association between prenatal attachment and prenatal depression [76,78,87,88,93,96,97,109,113] and one study regarding the association between prenatal attachment and postpartum depression [85]. Papers that included unemployed women [91,92,107,119], women with a low educational status [116], women with a low socioeconomic status [89][90][91][92], or women belonging to an ethnic minority [90][91][92] found a negative association between prenatal attachment and prenatal depression. One study that investigated African American pregnant women did not confirm the association between prenatal attachment and prenatal depression [80]. One study focused on women with a low educational status confirmed the association between prenatal attachment and postpartum depression [116].
Considering the ten studies [22,75,79,84,87,97,100,102,103,120] that investigated the relation between prenatal attachment and prenatal depression among expectant fathers, a negative association was confirmed in four [22,75,97,120]. All these ten studies [22,75,79,84,87,97,100,102,103,120] were focused on males with a university education who were employed, and above 18 years old. None of the studies explored the association between prenatal attachment and postnatal depression within male samples.

Non-Normative Pregnancies
Regarding the three studies focused on the association between prenatal attachment and prenatal depression in high-risk pregnancies [78,84,97], conflicting results emerged. Two articles did not confirm a relation between the two variables [78,84]. In contrast, Pisoni, et al. [97] observed a negative association between prenatal attachment in men and maternal prenatal depression.
Considering the studies focused on participants undergoing Assisted Reproductive Technology (ART), two research did not observe an association between the two considered variables in either men or women at the 26th and the 36th week of gestation [76,103], while one study identified an association between prenatal attachment and both antenatal and postnatal depression [116].
Within the two studies that considered expectant parents who had dealt with one or more perinatal losses [87,107] (termination of pregnancy, miscarriage, therapeutic abortion, in utero death, or early neonatal death), Gaudet [107] found that higher levels of maternal prenatal depression were related to lower maternal attachment quality. Armstrong [87] found that a partner's depression was not related to own prenatal attachment.

Psychological Measures
Forty articles were focused on the association between prenatal attachment and prenatal depression, whereas eleven studies analyzed the association between prenatal attachment and postnatal depression [74,81,85,95,99,101,105,110,111,116,117]. All the studies included in the current systematic review (Table 1) [22,[74][75][76][78][79][80][81] adopted a quantitative approach based on the administration of self-report instruments. One article [91] also used qualitative in-depth interviews with a subsample of 12 women who obtained higher or lower Edinburgh Postnatal Depression Scale (EPDS) scores compared to the cutoff value. These narrative interviews were used to raise the informational representativeness of the quantitative results.
Most of the participants were between 18-49 years old (mean age: 30). Conversely, five studies considered women as young as 14 [74,78,91,118,119]. Regarding socioeconomic characteristics, the majority of the participants had a high school education or a college degree, had full-time employment, had a middle economic income, were involved in a stable relationship, and did not belong to an ethnic minority. On the contrary, very few studies focused on unemployed women [107], women with a low socioeconomic status [90,91], women with a low educational status [116], or women who belonged to a minority group [91].
Finally, three studies observed the relationship between the two considered variables in couples who had high-risk pregnancies [78,84,97]; another three did so in women or men undergoing ART [76,103,116]. Only two papers focused on couples [87,107] who were dealing with one or more perinatal losses-termination of pregnancy, miscarriage, therapeutic abortion, in utero death, or early neonatal death.

Discussion
The current systematic review aimed to review and systematize the international literature focused on the relationship between prenatal attachment and perinatal depression, with the objective to clarify and discuss the emerging results while providing useful information for clinical purposes. Following inclusion and exclusion criteria, 41 papers were included. A negative association was found in most of the studies included between prenatal depression and prenatal attachment as well as between prenatal attachment and postpartum depression. However, many studies failed to do so, and conflicting results emerged particularly within male samples and expectant parents in high-risk pregnancies.

Association between Prenatal Attachment and Perinatal Depression
Thirty-one of the studies included in this systematic review identified a significant negative association between prenatal attachment and perinatal depression [22,74,75,81,84,86,89-92,95,97-99, 101,102,104-108,110-112,114-120]. In contrast, three articles found a positive association between prenatal depression and some dimensions of antenatal attachment (i.e., the "physical contact with the fetus and sensitivity to the fetal movement" subscale of the MFAS [102], the "empathy" subscale of the German version of the MFAS [106], and the "fantasy" and the "maternal sensitivity to the fetus" factors of the PAI [94]. These latter findings can be interpreted in several ways. As stated by some authors [94,102], depressed mothers can be more liable to their body perceptions, feelings, and affects, which should not necessarily be considered positive. As such, higher scores on the sensitivity and fantasy dimensions that emerged among depressed women can be interpreted as negative indicators associated with their distressed condition, rather than the demonstration of a more connection with the fetus. Similarly, greater empathy can be positively related with psychological vulnerability [106]. However, as stated by Seymir, et al. [102], awareness about the fetus and higher perceptions and feelings about him or her, regardless of their quality, can contribute to a greater maternal attention towards the future child that in turn can promote the development of a stronger prenatal bond. Accordingly, these results need to be cautiously considered. Future studies focused on the dimensions of prenatal attachment rather than on its overall score can provide further information and clarify these findings.
Although this association was confirmed in the majority of the included studies focused on the relation between prenatal depression and prenatal attachment, it is necessary to interpret these results with caution due to the many studies that did not confirm these findings. As several authors mentioned, the absence of a significant association could be due to methodological issues-such as assessment time and low sample size-or to confounding variables that were controlled for and that consequently hid the effect of prenatal depression symptoms on prenatal attachment (e.g., social support or personality factors) [79,81,85,88,93,109,111,119].
In addition to the relation often found between prenatal depression and prenatal attachment, many studies (ten out of eleven studies) identified a negative association between prenatal attachment and postnatal depression [74,81,95,99,101,105,110,111,116,117], highlighting the influence of prenatal attachment on parents' mental wellbeing during the postpartum period. Parents who established a more immediate and internal attachment with the fetus and who attributed emotions or behaviors to him or her were more highly invested in pregnancy, less self-critical and less vulnerable to psychological symptoms [74,105,117].

Administration Time
The majority of the articles (19 out of 29) that assessed the association between prenatal attachment and perinatal depression by administering prenatal attachment measurement tools in the second or the third trimester of pregnancy, in line with the beginning of the perception of fetal movement and the development of prenatal attachment [32,135,136], found a significant negative association between prenatal attachment and perinatal depression: 16 out of 24 studies identified an association between prenatal attachment and prenatal depression [22,84,86,[90][91][92]97,98,102,[104][105][106]112,[115][116][117] and six out of seven studies between prenatal attachment and postnatal depression [74,95,101,105,116,117]. A significant negative association was also found when prenatal attachment tools were administered starting from the first trimester of gestation. Of the studies that evaluated antenatal attachment between the first and the second or third trimester of pregnancy, six out of ten confirmed the relation between prenatal attachment and prenatal depression [81,89,108,110,111,118]; three out of three found an association between prenatal attachment and postnatal depression [81,110,111]. Moreover, the only one study that evaluated prenatal attachment in the first trimester identified a negative relation with postpartum depression [99]. These findings suggest that clinicians can assess both prenatal depression and prenatal attachment also before the second trimester of pregnancy, in order to identify prenatal attachment problems at an early stage, especially in those cases where symptoms of depression emerged. An early detection of antenatal attachment difficulties can also be important to implement interventions aimed at the prevention of depressive symptoms in the postpartum period [81,89,94,99,108,110,111,118]. Finally, all of the studies that assessed prenatal attachment at a not non-specific gestational time point confirmed the association between prenatal attachment and postnatal depression [75,107,114,119,120].

Gender Differences
The studies highlighted a major interest in the association between prenatal attachment and perinatal depression among women [75,84]. The focus on expectant mothers is likely due to their main role during the transition to parenthood. They must combine their new maternal identity and family changes with their previous self-representations and lifestyles [137]. Several authors reported that women interacted more with the fetus as well as faced a greater risk of isolation from their families [25,73,77,138,139]. Previous studies highlighted that some of the most prevalent depressive episodes were reported by women [50,138,140,141]. Women with depressive symptoms tended to report lower caring toward the fetus [119], to become more ambivalent regarding the future baby, to express more negative comments, to dislike their bodies, and to be less involved in pregnancy [6,73,142,143]. It is noteworthy that a significant negative association between prenatal attachment and perinatal depression was found both among women younger than 18 [74,91,118,119] and older than 18 [75,81,84,89,90,92,95,98,99,101,102,[104][105][106][107][108]110,111,[114][115][116][117].
Despite the main role that women play during pregnancy and in the postpartum period, and despite their risk to incur psychological difficulties, fathers also face psychosocial challenges during these periods. During pregnancy, fathers can become psychologically vulnerable due to the increased amount of time they spend on housework, increased financial and management responsibilities, and lower medical support than their female partners obtain [144,145]. These changes can have a negative impact on paternal mood and on the development and stability of prenatal attachment [22,49,75]. Although fewer of the studies focused on the association between paternal prenatal attachment and paternal prenatal depression [146,147], a significant negative association emerged among fathers in four of the nine studies [22,75,97,120]. No studies explored the relation between paternal prenatal attachment and paternal postnatal depressive symptoms.
To the best of the present researchers' knowledge, only four studies have focused on the association between a partner's depressive symptomatology and own prenatal attachment [75,87,97,102]. Although Armstrong [87] and Seimyr, et al. [102] showed the absence of an association between a partner's depressive symptoms and own prenatal attachment, two studies identified a negative association between maternal prenatal depressive symptoms and paternal prenatal attachment scores [75,97]. These latter findings seem to confirm the key role of the woman for the development of the paternal identity and for the creation of a bond between the expectant father and the fetus [9]. Having a partner with depressive symptoms can imply less support and less involvement during pregnancy, which can decrease the marital adjustment that is required to develop prenatal attachment to a fetus [75,112,148]. These considerations have theoretical and clinical relevance, but they require further confirmation.

Sociodemographic Variables
The majority of the revised studies included women who were married or cohabiting, did not belong to an ethnic minority, who had a middle economic income, and had a high level of education [74,81,84,94,95,[99][100][101]104,106,[109][110][111][112]114,115,117]. Being in these advantageous conditions was not necessarily a protective factor for their mental health [53,59,78]. Within this population, most of the studies identified a significant association between prenatal attachment and perinatal depression: 17 out of 31 articles found a negative relation between prenatal attachment and prenatal depression (e.g., [75,81,84,86,98,102,[104][105][106]108,[110][111][112]114,115,117,118]); nine out of ten articles identified a negative association between prenatal attachment and postnatal depression (e.g., [74,81,95,99,101,105,110,111,117]). Women exposed to disadvantaged conditions such as belonging to an ethnic minority (e.g., being African American or Hispanic), with a lower socioeconomic status, or those who were unemployed, or with a low educational status, or who had low incomes were more likely to receive less social support. This can compromise women's mental health, which in turn can affect antenatal attachment [45,91,116,149,150]. Within this population, seven of the eight studies that assessed the relation between prenatal attachment and prenatal depression identified a negative association between these variables [89][90][91][92]107,116,119].

Non-Normative Pregnancies
It is noteworthy that in women with non-normative pregnancies (high-risk pregnancies or assisted reproduction conceptions), most of the studies did not demonstrate a significant association between prenatal depression and antenatal attachment [76,78,84,97,103]. Only Lamba, et al. [116] observed an association between prenatal attachment and perinatal depression in surrogates [116]. Furthermore, one study did find that maternal prenatal depression negatively influences paternal prenatal attachment in high-risk pregnancies [97]. As Pisoni et al. [97] stated, it can be supposed that lower prenatal attachment scores are more associated with the diagnosis of high-risk pregnancy rather than with perinatal depressive symptoms. Lower levels of antenatal attachment can be considered as the result of a defense mechanism against the probable loss of a fetus. These considerations could provide explanations to the lack of findings emerged within this population.
Considering the two studies [87,107] focused on women who had suffered previous losses, a significant negative association between prenatal depression and prenatal attachment was observed by Gaudet [107]. As stated by several authors, when a mother or a father experience one or more perinatal losses, they bear a heavy burden that can affect their mood and disrupt the creation of an antenatal attachment bond [151][152][153]. However, a partner's depression was not related to own prenatal attachment in the study by Armstrong [87].

Clinical Implications
The results identified in the current systematic review suggest that clinicians should carry out regular screenings for both depression and attachment quality during pregnancy [72,147,154]. Although conflicting results emerged, the negative association between prenatal attachment and perinatal depression found in most of the studies highlights the need for screening processes and preventive programs at an early stage of pregnancy. Interventions aimed at reducing depressive symptoms that can occur during the gestational period and that can impact the psychological wellbeing of expectant parents and the development of a positive prenatal attachment should be implemented [155][156][157][158][159][160]. To enhance this bond takes on a main role, considering its further influence on postnatal depression (as most of the studies included in the current systematic review reported) [74,81,99,105,110,111], and on other important factors involved in the wellbeing of the both parents and the child [28,29,[32][33][34][35]37,38,41,42].
Parental-fetal attachment can be modifiable by specific supporting interventions that are efficacious in promoting the quality of parental bonding [161][162][163][164][165]. These programs for parents-to-be should encourage parents' fantasies about their baby, their proximity to the future child, and their care of the fetus [102,147].

Strengths and Limitations
This review adds to the current knowledge on the association between prenatal attachment and perinatal depression in men, women, and in high-risk pregnancies. The high number of papers and the focus on different populations clarified the relationship between these variables providing relevant information for clinical use.
However, the findings must be considered in the context of the limitations of this study. First, this systematic review is not a meta-analysis and thus we cannot draw statistical conclusions on its findings. Second, the review only included papers published in English; it excluded results obtained in other languages that could provide a broader comprehension of the relation between prenatal attachment and perinatal depression.

Future Research Directions
First, considering the limited and conflicting data that emerged, further studies would be useful to consider the association between prenatal attachment and perinatal depression in male samples and in non-normative pregnancies more in-depth [22,75,84,97,107,120].
Furthermore, future studies interested in the relation between antenatal attachment and perinatal depression should control for potential confounding variables (e.g., social support or personality factors) that could affect the results, as well as strengthen the methodological design of the research (e.g., involve a higher number of participants) to clarify the conflicting results in some cases emerged in the current systematic review. This would yield clearer conclusions about the association between these variables, which could further orientate healthcare professionals toward implementing rigorous screening processes and interventions during patients' transition to parenthood.
Moreover, future studies are necessary to better understand the influence of prenatal depressive symptoms on the quality of the partner's transition to parenthood, which was underexplored in the studies included in the current systematic review [87,102].
In addition, most of the studies included considered subjects with a high socioeconomic status and women who were over 18 years old [75,78,80,81,92,99,101,115]. Only a few studies [90,91,119] analyzed samples containing women as young as 14 years or with socioeconomic disadvantages. Further studies that consider different sociodemographic contexts are necessary to better generalize the present results.
Finally, future systematic reviews should also include results of studies published in language other than English, such as Italian, Japanese, French, and Portuguese, which although they emerged through the databases that we consulted, we did not analyze according to our inclusion and exclusion criteria. This solution can provide a greater understanding of the relationship between prenatal attachment and perinatal depression.

Conclusions
Analyzing and systematizing the existing literature on the relation between prenatal attachment and perinatal depression, this systematic review found a significant negative association between prenatal depressive symptoms and antenatal attachment and between prenatal attachment quality and postpartum depressive symptoms across different populations in most of the studies it reviewed. However, conflicting results emerged, suggesting that these findings should be interpreted with caution. Further studies are needed to clarify the nature and the generalizability of this association. These results could provide important information for clinical purposes such as implementing screening processes and interventions aimed at reducing the psychological impact of the transition to parenthood and at improving familial wellbeing.
Author Contributions: Creation of the frame used in this review and the selection of the papers: L.R., M.G., and T.T. Review of the literature: M.G. and F.S. Searching of the articles discussed in the review, data extraction, and interpretation of the results: L.R., M.G., and T.T. Supervision of the entire work: L.R. and T.T. All authors were involved in the discussion, writing and revision of the manuscript and they gave the final approval of the version to be published. All authors have read and agreed to the published version of the manuscript.