The study used a longitudinal design and is part of a previous published project ‘Pregnant women and new mothers' health and life experience, with ‘life experience’ which also included collecting data around intimate partner violence [3, 18, 19]. Included participants were primigravida and multiparous women ≥18 years of age, receiving antenatal care (ANC), and who could read and write in Swedish or English.
Participants
Recruitment to the study was performed prospectively between March 2012 and September 2013 area in the southwest of Sweden, which is multiethnic. The study population includes all pregnant women at total 17 ANCs situated in the multiethnic city, a University City and in smaller municipalities. In the present study, more than 50% of the women lived in the multicultural city were almost a third of the inhabitants are born abroad and come from 186 different countries. Overall, the participants in the present study represented 93 different countries. Altogether, 1939 pregnant women were recruited to the study. Recruitment usually occurred early in the second trimester (mean, 12.8, SD 5.11) [3] by midwives working in maternal health care. Further details regarding the recruitment process and the study setting are described in detail in another paper [3].
Data collection
The available dataset included in the study involved the health records of 1694 mothers who gave birth between June 2012 and April 2014 (Fig 1).
Survey and Tools
Questionnaires (QI and QII) were administered and completed early in the second trimester and again in late pregnancy, usually around gestational week 34 (mean 33.9; SD 2.20) information was also extracted from the birth register regarding the women’s birth outcomes.
Questionnaires included (Q-I – Q-II) the NorVold Abuse Questionnaire (NorAQ) which has been used previously for collecting similar data demonstrating its validity and reliability [29]. Other questionnaires included Edinburgh Postnatal Depression Scale (EPDS) [30], which is common tool used during pregnancy (EDS) and following childbirth to access a woman’s risk of developing postnatal depression [31]. The EPDS has a 72% sensitivity and 88% specificity for women in the postpartum period but has a lower degree of detection for depression during pregnancy [32]. The cut-off score for depression is usually set at 12/13 [30] the cut off chosen for this study was 13. The sense of coherence (SOC) scale measured the women’s’ stress management and their use of own resources to maintain and improve health. The instrument is reliable, valid and cross-culturally appropriate with acceptable face validity and consists of 13 items [33]. A high SOC score is a predictor of good health and is strongly related to perceived health, especially mental health [34]. The Alcohol Use Disorders Identification Test (AUDIT) [35] was also used at each time of questionnaire administration (Q-I – Q-II). For this study, the women were only asked the first question; How often do you have a drink containing alcohol? In Sweden, the AUDIT questionnaire is routinely used in antenatal care to collect information about the woman’s alcohol intake during pregnancy.
Classification of the variables
For sociodemographic factors as well as maternal characteristics similar or same classifications were used as in previous publications, but the material has same origin [3, 18, 19]. Age was classified as 18–25, 26–34 and ≥ 35 years. Cohabiting status was classified as single/living apart, or common law spouse/married. Language was dichotomised as Swedish language or foreign language spoken at home (including English). Educational status was classified as compulsory school or less to low educational status and, high school or less, or university to high educational status. Employment status was dichotomised as employed (including parental leave and studying) or unemployed (including long illness). Financial distress was dichotomised as “no” (no problem) or “yes” (serious financial distress). The question about financial distress was as follows; If you received unexpected bill of 20.000 SEK, how easy would it be for you to pay within a week? Responses included; no problem, fairly hard and very hard, which is expressed as ‘serious financial distress’.
Maternal characteristics included Parity which was classified as primiparous versus multiparous. Body mass index (BMI) were calculated from maternal weight and height before the pregnancy and classified according to WHO’s definition as underweight (<18.5) / normal weight (18.50- 24.99) versus overweight (≥25- 29.99) / obese (≥30). Smoking/using wet tobacco was dichotomised into “yes” (if the woman was a daily smoker/snuffer or smoking/snuffed at some point during pregnancy) and “no” (never smoked/wet-tobacco or ceased before pregnancy). Use of alcohol was dichotomised into “yes” (at least once a month or more) or “no”. Fear of Birth yes or no.
For birth and labour outcome Labour initiation was dichotomized into spontaneous or induction (regardless of diagnosis or how the induction was initiated). Augmentation of labour was dichotomized into yes (with synthetic oxytocin) or no. The use of Epidural anaesthesia was dichotomized into yes or no. Birth mode were classified as vaginal birth (inclusive vacuum extraction and forceps) or caesarean section (inclusive planned and emergency section). Postpartum haemorrhage (PPH) was classified as bleeding < 1000 ml or ≥ 1000 ml.
For infant characteristics and birth outcome gestational week was classified as premature < 37 and as full term from ≥ 37 weeks of gestation. Infant biological sex was dichotomized into female or male. Apgar scores at 5 min classified as < 7 or ≥ 7. Infant weight was distributed between < 2500g, 2500-4000g and > 4000g. Transferred to Neonatal Intensive Care Unit (NICU), was dichotomized into yes or no.
Data analysis
Descriptive statistics were utilized to show prevalence. The t-test was used to compute mean age. Chi-square analysis was used to investigate differences in variables presenting sociodemographic, maternal characteristics, birth and labor outcome as well as infant characteristics in relation to ‘history of violence’. OR and 95% CI were calculated for the crude associations between possible risk factors and ‘history of violence’, with ‘birth outcome’ as a dependent variable for bivariate logistic regression. In order to analyze the association between the SOC score and exposure to ‘history of violence’, the SOC-scale was dichotomized utilizing the first quartile of the distribution as a cut-off value (SOC≤ 64 and SOC >64) [36]. The SOC score was only subtracted for those responding to all thirteen items (missing = 95). To analyze the association between symptoms of depression during pregnancy an optimal cut-off of ≥ 13 was chosen as representing the presence of symptoms of depression [31]. The EDS score was calculated solely for those replying to all ten questions (missing = 53). Statistical significance was considered at p < 0.05 (two-tailed). Statistical analyses were performed using the Statistical Package for Social Sciences (SPSS) version 25.0 for Windows.