Intimate Partner Violence and Pregnancy: A Systematic Review of Interventions

Abstract Background Intimate partner violence (IPV) around the time of pregnancy is a widespread global health problem with many negative consequences. Nevertheless, a lot remains unclear about which interventions are effective and might be adopted in the perinatal care context. Objective The objective is to provide a clear overview of the existing evidence on effectiveness of interventions for IPV around the time of pregnancy. Methods Following databases PubMed, Web of Science, CINAHL and the Cochrane Library were systematically searched and expanded by hand search. The search was limited to English peer-reviewed randomized controlled trials published from 2000 to 2013. This review includes all types of interventions aiming to reduce IPV around the time of pregnancy as a primary outcome, and as secondary outcomes to enhance physical and/or mental health, quality of life, safety behavior, help seeking behavior, and/or social support. Results We found few randomized controlled trials evaluating interventions for IPV around the time of pregnancy. Moreover, the nine studies identified did not produce strong evidence that certain interventions are effective. Nonetheless, home visitation programs and some multifaceted counseling interventions did produce promising results. Five studies reported a statistically significant decrease in physical, sexual and/or psychological partner violence (odds ratios from 0.47 to 0.92). Limited evidence was found for improved mental health, less postnatal depression, improved quality of life, fewer subsequent miscarriages, and less low birth weight/prematurity. None of the studies reported any evidence of a negative or harmful effect of the interventions. Conclusions and implications Strong evidence of effective interventions for IPV during the perinatal period is lacking, but some interventions show promising results. Additional large-scale, high-quality research is essential to provide further evidence about the effect of certain interventions and clarify which interventions should be adopted in the perinatal care context.


Introduction
Intimate partner violence (IPV) is increasingly recognized as a global health problem with crucial societal and clinical implications.IPV affects women and men from all backgrounds, regardless of age, ethnicity, socio-economic status, sexual orientation or religion [1][2][3].IPV is defined as any behavior within a current or former intimate relationship that causes physical, sexual or psychological harm, including acts of physical aggression, sexual coercion, psychological abuse and controlling behaviors [4].It is sometimes referred to as domestic/family violence, spouse/partner abuse/assault, battering, violence against women or gender based violence.[4][5][6].
Pregnancy and childbirth are major milestones in the lives of many couples and their families.The transition to parenthood brings joy as well as new challenges to couple relationships [7,8].
Pregnancy can be a time of particular vulnerability to IPV because of changes in physical, emotional, social and economic demands and needs.This vulnerable period, however, is not limited to the time between conception and birth.Researchers have clearly demonstrated that the risk factors for IPV associated with pregnancy encompass the timeframe of one year before conception until one year after childbirth [3,[9][10][11][12].
A wide range of prevalence rates, from 3 to 30% of IPV around the time of pregnancy, has been reported.Prevalence rates in African and Latin American countries are mainly situated at the high end of the continuum and the European and Asian countries at the lower end.Although estimates within regions and countries are highly variable, the majority of studies show rates within the range of 3.9% to 8.7% [2,13].Most studies focus mainly on physical and/or sexual partner violence, while psychological violence remains difficult to delineate and measure.Although the exact prevalence of IPV around the time of pregnancy remains unclear, it is evident that it affects a substantial group of women.In fact, IPV during the perinatal period is more common than several maternal health conditions (e.g.pre-eclampsia, placenta praevia), nevertheless IPV receives considerably less attention within perinatal care [2,3,14,15].
In recent decades, research from the western world and increasingly from low and middle income countries [16] has generated growing evidence that violence is associated with detrimental effects on the physical and mental health of women, men and children [17].IPV is associated with adverse pregnancy outcomes such as low birth weight, preterm delivery, infection, miscarriage/abortion, placental abruption, fetal injury and perinatal death.Adverse mental health consequences and behavioral risks including depression, anxiety disorders, post-traumatic stress disorder, suicide (attempts), delayed entry into prenatal care, poor maternal nutrition and use of tobacco, alcohol and illicit drugs are consistently associated with IPV around the time of pregnancy [4,14,[17][18][19][20][21][22][23][24][25][26][27][28][29].Most researchers and caregivers agree that perinatal care is an ideal 'window of opportunity' to address IPV, for it is often the only moment in the lives of many couples when there is regular contact with health care providers [2,30].There is a growing consensus that routine enquiry is a safe effective practice and an important first step in tackling IPV in general [24,[31][32][33][34][35].Nevertheless, a lot remains unclear about how to deal with IPV in the perinatal care context and which interventions should be adopted.
The objective of this paper is, therefore, to provide a clear overview of the existing evidence on the effectiveness of interventions for IPV for women (and their partners/children if the intervention involves them) during the perinatal period.This review surveys randomized controlled trials (RCTs) of all types of interventions aiming to reduce IPV, and/or enhance physical and/or mental health, Quality Of Life (QOL), safety behavior, help seeking behavior, and social support.

Search strategy
This systematic literature review was based on an extensive search in the electronic databases PubMed, Web of Science, CINAHL, and the Cochrane Library We started our search in PubMed and applied the same strategy in Web of Science, CINAHL and the Cochrane Library.Reference lists of retrieved articles were checked and relevant articles were added by hand search.The database search was executed by two reviewers (ASVP & AV) independently, findings were discussed and differences resolved.
Figure 1 gives a detailed overview of the search strategy.

Inclusion criteria
Several criteria for inclusion in the systematic review were applied.
First of all, the type of participants included in the studies for this review were pregnant women of any age and/or women who had given birth in the past year (plus their partners/children if the intervention involved them).
Second, the studies had to aim at evaluating some type of intervention for IPV.Peer-reviewed papers reporting on interventions only addressing non-partner violence, reproductive coercion, child abuse/neglect, parenting, teen pregnancies, substance abuse, and disclosure of IPV were therefore excluded.Publications were also examined to ensure that they did not display the same data set as that displayed in other articles.
Third, the primary outcome of the studies had to be any measure of IPV.The secondary outcomes were physical and/or psychosocial health (e.g.pregnancy and neonatal outcome, depression, anxiety, QOL, substance use, stress), help seeking behavior, safety behavior and social support.
Fourth, we included only published RCTs, regardless of the nature, intensity or duration of the intervention, length of followup, or country or setting in which the participants were recruited.

Quality assessment
After full text evaluation, the risk of bias and the quality of the selected studies was assessed by two reviewers (ASVP & AV) separately, based on ''The Cochrane Collaboration's tool for assessing risk of bias'' [36].Key domains of this risk of bias assessment were sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting and 'other issues'.The reviewers independently assessed risk of bias for each study and classified every study as low, high or unclear risk of bias.Final classifications and inclusion in this review were determined by consensus.For a detailed overview of the quality assessment, see Table 1: Characteristic of the included primary studies.

Data extraction
Using a specially designed data extraction form, the two reviewers independently extracted information from the selected papers.Data items compromised country, setting, sample size & participants, sampling methods, measuring tools, description of the intervention and control group(s), outcomes, and follow-up period.Authors were contacted if additional information was required.
Initially, we planned a meta-analysis to quantify and compare the interventions identified.Unfortunately it was not feasible to perform a meta-analysis due to the limited amount of data and the large variation in interventions, outcome measures and measurement time points.
The PRISMA guidelines were used as a framework for this review [37].

Results
Through our electronic database search, we retrieved 412 potentially relevant articles based on keywords and limits set (60 in PubMed, 343 in Web of Science, seven in CINAHL and two in the Cochrane database).Fifteen additional articles were identified through hand search.After title and abstract evaluation, 69 duplicates were removed, leaving 343 to be included in the next step.Thereafter, out of 358 articles (343+15 articles retrieved through hand search) screening resulted in 17 articles deemed eligible for more detailed evaluation.After full text evaluation another eight were excluded because they did not meet the inclusion criteria, leaving nine studies submitted to critical appraisal and included in this systematic review [17,[38][39][40][41][42][43][44][45].Details on setting/participants, intervention/control activities and outcomes are given in Table 1: Characteristic of the included primary studies.
Out of these nine studies, six were conducted in the USA, one in Peru, one in Australia, and one in China.All studies recruited participants through hospital-based antenatal care, with sample sizes ranging from 50 to 1054 women.
Three studies measured the impact of a home visitation program involving paraprofessionals (non-professionals trained to do the home visits and deliver the intervention), mentor mothers (lay mothers trained to do the home visits, provide peer support and mentoring), and/or nurses and followed participants for between one up to nine years.
The six other studies evaluated the effect of some form of supportive counseling, varying from one 30-minute session up to six 60-minutes sessions or 24/7 access to a Nurse Case Manager (NCM).Most (n = 6) of the interventions were specifically designed to target IPV as the main objective, but some (n = 3) were part of a larger, multifaceted intervention in which IPV was one of the targets parallel to e.g.smoking, depression, child health, parenting.All studies compared the intervention to usual or standard care, which, due to ethical considerations, generally implied that patients were provided a referral card or a list of community resources.
Throughout the rest of this paper the term IPV will be used to refer to the combination of physical and sexual and psychological partner violence, unless specified otherwise.

Home visitation programs
Primary outcome.After three years of program implementation Bair-Merritt et al. [41] found that, intervention women reported a lower, albeit statistically marginally non-significant, adjusted rate of IPV victimization [Incidence Rate Ratio (IRR) 0.86, 95% CI, 0.73-1.01]and a significantly lower rate of perpetration (IRR 0.83, 95% CI, 0.72-0.96)than the control group.Intervention women showed significantly lower rates of physical assault victimization (IRR 0.85; 95% CI, 0.71-1.00)and significantly lower perpetration (IRR 0.82, 95% CI, 0.70-0.96).Although rates of overall IPV victimization and perpetration were also lower after 9 years, these results were not statistically significant.In other words, perpetration rates decreased significantly and victimization rates showed a trend towards decrease after three years, but not after nine years.Olds et al. [44] found on the one hand, no adjusted statistically significant effects of paraprofessional visits on the experience of physical partner violence in the intervention group (IG) versus the control group (CG) (14.2% vs. 13.6%,P = 0.88, OR 1.05, 95% CI not reported) in the six months prior to four year follow-up.On the other hand, nurse-visited women did report (6.9% vs. 13.6%,P = 0.05, OR 0.47, 95% CI not reported) a significant decrease in physical partner violence.
Cripe et al. [17] reported no statistically significant differences in the occurrence of IPV between the intervention and control groups after an empowerment counseling session.
Curry et al. [42] did not report any results on IPV, nor were the authors able to provide the IPV data we requested.
Humphreys et al. [43] found no statistically significant differences in prevalence of physical and/or sexual partner violence between the two groups at baseline and did not report partner violence after intervention.
The intervention by Zlotnick et al. [38] did not significantly reduce the likelihood of IPV during pregnancy or up to three months postpartum.
Curry et al. [42] found no statistically significant decrease of total stress scores between the two groups, although total stress scores of both intervention and control women significantly decreased (P,0.001) between follow-up periods.
The intervention by Zlotnick et al. [38] did not significantly reduce the likelihood of a major depressive episode or post traumatic stress disorder (PTSD).They found a trend towards decrease during pregnancy but not during postpartum.
Cripe et al. [17] found a trend towards improved QOL, safety and help seeking behaviors (church and police) in the IG, but no statistically significant differences between the two groups.
The following figure 2 gives illustrates the correlations between the type of intervention and the impact on the reduction of IPV.

Discussion
The results of our systematic review demonstrate that there are few RCTs evaluating interventions for IPV during the perinatal period.Moreover, the overall quality of the nine studies identified is limited and did not produce strong evidence that certain interventions are effective.This finding is also endorsed by Jahanfar et al. [46].The evidence of IPV interventions outside the context of pregnancy remains similarly insufficient and inconclusive [24,31,[47][48][49].
Nevertheless, five out of nine studies in our review reported a statistically significant decrease in some form of IPV (odds ratios from 0.47 to 0.92).The most promising results identified by this review are to be found in the home visitation programs and multifaceted counseling-interventions.The three studies [39,41,44] on home visitation programs all showed a statistically significant decrease in IPV victimization (and one in perpetration).However, although Olds et al. [44] noted a significant decrease in physical IPV for the nurse-visited women, this was not found for the paraprofessional-visited women.The authors attributed this finding to an increased emphasis among the nurses on partner violence, but it remains unclear if this was really the case.With regard to the secondary outcomes, Olds [44] reported significantly better mental health, fewer subsequent miscarriages and low birth weight newborns in the paraprofessional-visited but not in the nurse-visited women.The different impact of nurses and paraprofessionals raises questions about the mechanisms through which the interventions affected the outcomes.
It is interesting to note that out of six studies evaluating different types of supportive counseling, only two reported a statistically significant effect of the intervention on IPV.First, the high-quality study by Kiely et al. [40] found that their cognitive behavioral intervention significantly reduced recurrent episodes of IPV (except for sexual IPV).Second, Tiwari et al. [45] reported significantly less psychological and minor physical (except for sexual IPV) violence in the intervention group.Sexual partner violence seems to be a form of violence that is difficult to influence.The other four studies [17,38,42,43] did not find a significant difference in IPV between the intervention and control groups.
Concerning secondary outcomes, Kiely et al. [40] observed significantly fewer very preterm neonates and an increased mean gestational age in the intervention group.Tiwari et al. [45] reported significantly fewer women with postnatal depression and improved QOL in the intervention group.
None of the studies reported any evidence of a negative or harmful effect of interventions, although only one study [43] mentioned assessing potential harms caused by intervention.
The results should be interpreted with caution and within the light of serious methodological challenges.Researching violence is inherently associated with numerous ethical and safety issues, making it very difficult to produce strong evidence.We identified considerable variation in categorizing certain behavior as IPV, research settings, study populations, sample sizes, content of the intervention, and length of follow-up.Intrinsic to the difficulties associated with the study subject sample sizes are small, there is a considerable loss to follow-up, and it is impossible to blind respondents.Moreover, few studies adjusted their analysis for confounding factors (e.g.childhood abuse), which can create an oversimplified image of reality.However, it should be remembered that lack of statistically significant results does not necessarily imply clinical irrelevance.Some interventions might be effective but not have reached significance level due to methodological and/or ethical challenges.
It is striking that five out of the nine studies reported decreases in IPV after a certain point in time but that these decreases did not significantly differ between intervention and control groups.Apparently, with time (certain) wounds heal.However, other explanations can also be hypothesized.
First, as far as we know, in all the studies reviewed, identifying IPV was not part of routine perinatal care but an additional research-related activity (also known as the Hawthorne-effect) [31,34].Asking IPV-related questions to women in the control group, mostly in combination with handing out a referral card could have had a larger impact than assumed.McFarlane et al. [30] found that ''simple assessment of abuse and offering referrals has the potential to interrupt and prevent recurrence of IPV''.In other words it is possible that the 'intervention' in the control group is more effective than anticipated and therefore no clear difference between the two groups is detected.
Second, it seems reasonable to question the legitimacy of using IPV as a main outcome measure.Given the complexity of intervening factors between identification and IPV reduction (with many not under the control of health care providers), interventions should not necessarily be expected to decrease IPV [35].Internal changes (mental health, QOL, …) are potentially more informative for evaluating the impact of an intervention for IPV.Significant changes in active or passive experiences of violence may not be observable for some time [5,47,48,50].At the time of measurement, respondents might simply not acknowledge the violence, or be ready to make changes or accept help.Some counseling interventions (developing safety plans, seeking help, …) might come too early and/or are not adapted to specific needs and therefore prove ineffective [51,52].In this review, we identified only one study [43] that included some measure of 'readiness to change' which might have contributed to the lack of significant results.
Furthermore, our systematic review yielded only one study [41] reporting both maternal victimization and perpetration behavior, in which there is the striking observation that the rate of perpetration acts in women was twice as high as the victimization acts in both intervention and control groups (at baseline).The intervention seemed to reduce mainly maternal perpetration behavior, but paternal victimization nor perpetration behavior was not directly measured.This finding adds to the debate on gender symmetry in the perpetration of violence and the discussion about over-disclosure by women and under-disclosure by men.Yet, pregnant women's use of violence is virtually ignored by most authors [3].Moreover, Hellmuth et al. [53] found that IPV perpetration during pregnancy and/or postpartum is associated with negative health outcomes.Therefore, measuring only subjection to violence as a measure of effectiveness of an intervention seems quite insufficient.More attention should be given to outcome measures reflecting the complex process of changing destructive interaction dynamics.
We are aware that this systematic review has several limitations.The choice of databases, inclusion criteria, risk of bias assessment, and interpretation of results all required the individual judgment of the authors.We took various steps to minimize bias at all stages of the review process, but a different review team may not fully agree with our assessment.

Conclusion
This systematic review indicates that strong evidence of effective interventions for IPV during the perinatal period is lacking.Nonetheless, home visitation programs and some multifaceted counseling interventions produced promising results.It is obvious that additional large-scale, high-quality research (with metaanalysis) is essential to tackle the remaining questions and provide further evidence about the effect of certain interventions.Future research should focus on several levels simultaneously (individual, relations, community, and society).Intervening in a single risk factor may be unsuccessful because other risk factors may persist as barriers to the desired change.Readiness to change, help seeking strategies and the complex mutuality of IPV should be taken into account.Serious thought should be given to appropriate outcome measures and to including process indicators in evaluating effectiveness.

Table 1 .
Characteristic of the included primary studies.