The study was registered with the clinical trials network code (IRCT2017040628352N4), and all the required permissions have been obtained from Zanjan University of Medical Science with the registration code (ZUMS.REC.1396.37). Samples were collected from childbirth preparation class located in comprehensive urban health care center three in Zanjan, Iran.
Setting and participants
Overall, 267 pregnant women completed the conflict tactic questionnaire and 158 individuals had minor and medium levels of domestic violence based on conflict tactics scale (CTS-2). The rest of them were excluded from the study due to reasons such as absence of violence, unwillingness to participate in the study, the existence of extreme violence (n=2), not living in the city of Zanjan (n=3), and being diabetic (n=1). Eventually, 90 pregnant women entered into the study and completed the demographic, reproductive, and the quality of life questionnaires (SF-36) from which 45 women were randomly assigned to the intervention group, and the other 45 women were assigned to the control group. In the intervention group four participants were excluded from the study, due to reasons of unwillingness to continue participation (n=3) and having eclampsia (n=1). Also, in the control group four participants were excluded from the study, due to unwillingness to continue participation. Eventually, the data from 82 pregnant women, which included 41 individuals in each group was analyzed (Figure 1).
The inclusion criteria comprised minor and medium levels of domestic violence in physical, psychological, and sexual sub- scales of the CTS-2 in mothers, being over 18 years old, being less than or equivalent to 27 weeks of pregnancy based on Last Menstrual Period (LMP) or ultrasound results, literacy, living in the city of Zanjan, being married for at least a year, having no participation in any other classes or counseling courses simultaneously, having cell phones, absence of underlying illnesses, lack of any known psychological illnesses, lack of psychoactive drug consumption, having no signs of addiction to drugs in pregnant women and their spouses, absence of past-year stressful life events to women or their spouses, absence of pregnancy complications such as preeclampsia, hemorrhage, etc., willingness to participate in counseling sessions and living together as a couple.
The exclusion criteria included unwillingness to continue participation in the study, absence of pregnancy complications such as preeclampsia, etc., and being absent in more than one counseling sessions.
In the intervention group, counseling sessions based on solution-focused approach were held weekly for a period of six weeks in the form of 90- minute counseling sessions at childbirth preparation place. The themes in each session were as follows: the aims of the first counseling session include highlighting general principles of solution-focused counseling and providing proper definitions of problems to clients. The second session focused on the familiarity of participants with the concept of quality of life and solution-focused approach. During the third session, clients learnt that there are different interpretations for an event and that they can develop the best interpretation in their minds while in the fourth session, clients were encouraged to discover exceptional opportunities of living as a couple. In the fifth session, with the help of magical questions, participants were able to recognize their destructive behavior patterns; while in the sixth session, a conclusion was made from the whole previous sessions to help the clients replace and experience their former thoughts and behaviors with the new ones. However, the control group only received the routine care. Six weeks after the last counseling session, both groups were invited to complete the study tool for the second time. At this time the session was conducted in the presence of an interviewer who was completely unaware of the grouping procedure.
Participants were selected through a convenience sampling method and divided into two intervention (A) and control (B) groups using, quadruple random blocks. At first, all sequences of participants in each block was considered and then 23 blocks sequence was selected from random table number. The overall number of 90 pregnant women entered into the study from which 45 individuals were allocated to intervention and 45 individuals to the control group.
Data collection tools
Research tools for collecting data included demographic and reproductive checklist, CTS-2, and health-related quality of life questionnaire (SF-36); which were completed by qualified women. Demographic data included couple's age, couple's employment, couple's residential address and education status, marriage longevity, economic status, having cell phones, number of marriages and having children from the previous marriage. Reproductive data related to pregnancy status included pregnancy duration, frequency of pregnancy and delivery, intended and unintended pregnancies, and infertility history. In order to identify whether pregnant women were at risk of domestic violence; CTS-2 was applied. The questionnaire is the newly revised version of the conflict tactics scale in addressing marital conflicts which was developed by Straus et el. (1996) with the confirmed Cranach's Alpha of 79% for physical violence and 86% for psychological violence .
The applied questionnaire in the present study was validated by Eftekhar ardabili et el. (2010) with the Cronbach's Alpha of 80%  which comprised 36 questions studying the conflict tactics on different dimensions of negotiation, physical, psychological, and sexual violence that leads to injuries. Although, the applied criteria in measuring the frequency and severity of violence in the CTS-2 is considered to be from last year, according to the questionnaire designer, one year is predetermined and could be generalized to the desired time expected by the researchers . Thus, in the questionnaire associated with the present study, instead measuring the previous year, three months' period was accounted for measurement. The SF-36 was applied for measuring the quality of life of participants, which included 36 questions and its validity in Iran has been verified by Montazeri et el. (2010) with the Cronbach's Alpha of 77% to 90%. This tool evaluates the quality of life in two dimensions of physical and psychological health. Each dimension contains four subscales. Physical subscales include physical function, role limitation-physical health, bodily pain and general health and psychological dimension include vitality, psychological health, role limitation-emotional health, and social functioning .
The outcomes of the present study included domestic violence and the quality of life in pregnant women who had been exposed to domestic violence which were measured and evaluated between the two intervention and control groups at six weeks follow ups.
According to the reported domestic violence difference between the two intervention (81.46±33.64) and control (113.40±64.71) groups in Tafreshi et al.  study, the error of 5%, and the power of 80%, 41 individuals needed in each group and by counting 10% drop-outs, 45 individuals were entered into each group.
The collected data were analyzed using SPSS V.16 and R statistical software. In order to study the normal distribution of variables, Kolmogorov– Smirnov test was applied. Qualitative data were analyzed using Chi-square and Fisher tests. In order to compare conflict tactics scale and the quality of life sub-scales between the two groups of intervention and control at baseline, independent t-test and Mann- Whitney U test were used. Due to the non- normal distribution of variables and the absence of parametric ANCOVA defaults; non- parametric ANCOVA was applied to compare the differences between the two groups adjusted for baseline measures. Also, for comparing the conflict tactics scale, the quality of life, and their sub-scales between different phases of study, Wilcoxon and paired t-test were applied. The significance level of the aforementioned tests was based on P value <0.05. The economic class was calculated considering factors such as house foundation, housing, and transportation means. In addition to that, for calculating social and economic levels, factors such as job ranking, education, and economic class were taken into consideration.