Research design and sample
A cross-sectional survey was conducted from July-October, 2019 among pregnant women in urban communities of Hengyang City, Hunan Province, China. A multi-staged cluster random sampling method was used in this study. There are 5 districts in urban Hengyang. In the first stage, a street from each district was randomly selected: Zhengxiang Street, Qingshan Street, Baishazhou Street, Guangdonglu Street and Zhurong Street. In the second stage, proportional sampling was carried out at a proportion of 1/3 to randomly select 4 communities in Zhengxiang Street, 3 communities in Qingshan Street, 3 communities in Baishazhou Street, 2 communities in Guangdonglu Street, and 2 communities in Zhurong Street. In total, 14 communities were selected for this study. All pregnant women who were registered in community health service centres and who met the inclusion criteria were potential subjects in this study. The inclusion criteria for the study were as follows: 1. women in the third trimester of pregnancy; 2. pregnant women over 16 years old; and 3. pregnant women who had local household registration, or migrant people who had lived in urban areas of Hengyang city for more than 6 months. The exclusion criteria were: 1. pregnant women with cognitive disorders, severe mental illnesses or other serious diseases who cannot fill out the questionnaire by themselves; and 2. pregnant women who refused to participate in the study. There were 819 registered samples in the 14 selected communities, of which 6 were excluded because of refusals to respond and failure to contact; therefore, 816 pregnant women who met the requirements participated in the study. The response rate was 99.3% (813/819).
All subjects gave their informed consent for inclusion before they participated in the study. The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Ethics Committee of Xiangya School of Public Health, Central South University (XYGW-2019-056).
Data collection and measurements
General characteristics were collected, including age (＜26, 27-32,＞33), ethnicity (minority, Han ethnicity), marital status (stable, unstable), monthly per capita household income (≤3000, 3001-5000, 5001-8000,＞8001), education level (senior school / technical school or less, college / university degree or above), occupation (employed, unemployed), partner’s education level (senior school / technical school or less, college / university degree or above), partner’s occupation (employed, unemployed), whether they had medical insurance，whether they had a smoking habit, whether they had a drinking habit, the partner’s smoking habit, the partner’s drinking habit, the mode of pregnancy (natural conception, artificial impregnation), history of delivery (≤1,＞1), pregnancy intention (intended, unintended), whether they had experienced multiple abortions/sterility, whether they had received antenatal examinations, whether they had pregestational diseases (depression or diabetes), and whether they had pregnancy complications (gestational diabetes, pregnancy-induced hypertension, intrahepatic cholestasis of pregnancy, and others). Being married was defined as being in a stable marriage. Unstable marriages included unmarried, divorced, and widowed.
Family factors consisted of four aspects: family relationships, family structure, family-related stressors and family function. Family relationships were evaluated on two dimensions: the relations with the mother-in-law (good, bad) and relations with other family members (good, bad). Family structure included the number of cohabitants (1-2,＞3) and whether they lived with elders. In terms of family relation stressors, three family negative life events were listed: whether they had medium household debt, whether they were separated from their partner, and whether their partner had extramarital relations. The Family Adaptation Partnership Growth Affection and Resolve Index (APGAR) is a tool for evaluating family functions. The Family APGAR has five items, and each item was answered on a 3-point Likert scale from “often” (2 points) to “rarely” (0 points). The total score was 0-10 points. High family APGAR index scores ranging from 7 to 10 points indicated good family function, middle family APGAR index scores ranging from 4 to 6 points indicated moderate family dysfunction, and low family APGAR index ranges from 0 to 3 points indicated severe family dysfunction. Family APGAR index has been widely used and has good reliability and validity[27, 28]. The Cronbach's α is 0.876.
Assessment tools for DV
The Abuse Assessment Screen Questionnaire (AAS) was compiled in 1995 by McFarlane and translated into Chinese by Leung of the University of Hong Kong and was used to assess DV during pregnancy. There are eight items in this scale assessing mental, physical and sexual violence as well as the psychological response to perpetrators in three periods: lifetime and 12 months prior to and during pregnancy. The response to each item was either Yes or No. If the interviewee answered “Yes” to one or more of Questions 5 to 7, she was identified as a victim of DV during pregnancy[29, 30]. The scale’s Cronbach's α is 0.685. These scales are widely known as self-management tools for screening DV with good validity and reliability.
EpiData 3.1 and SPSS 19.0 software were used for data entry and statistical analysis. Categorical variables are expressed as n (%), the χ2 test was applied for comparisons of characteristics between pregnant women who had experienced DV and those who had not (no DV group), and the variable of p＞0.05 was used as the adjustment variable. The crude odds ratio (COR) was reported by univariate binary logistic regression models. For instance, the multivariate binary logistic regression models were conducted to estimate the effect of family factors on DV, and adjusted odds ratio (AOR) and 95% confidence interval (95% CI) were reported. The statistical significance level was accepted as p＜0.05. All statistical tests were 2-sided.