Birth weight was associated with maternal exposure to intimate partner violence during pregnancy in southern Ethiopia: A prospective cohort study

Introduction: Birth weight is defined as the first weight of the newborn, ideally measured soon after birth. A recent Ethiopian survey estimated that 48% of births took place in health facilities. Data for women exposed to intimate partner violence (IPV) may be lacking in official statistics because these women may prefer to deliver at home, where data from non-institutional births, including reporting of birth weights, are not routinely recorded. Objective: The aim of this study was to investigate the association between maternal exposure to IPV during pregnancy and birth weight in a community in the Wondo Genet district of southern Ethiopia. Methods: We carried out a community-based prospective cohort study from February to December 2017. We followed up with 505 pregnant women and their newborns until after delivery. An interview about partner violence was done during pregnancy at home when enrolled. Field assistants who visited the homes measured the birth weight of each baby in grams. Twins and late birth weight measurements were excluded. Factors associated with birth weight were assessed by multiple linear regression. Results: Birth weight was assessed within 48 h for 477 (94.5%) newborns and between 48 and 72 h for an additional 28 (5.5%). There were 365 (72.3%) institutional deliveries. In an adjusted regression analysis (IPV adjusted for socio-economic status), birth weight was 203 g lower (B −203 95% CI −320 to −87) among newborns of women exposed to IPV than among the unexposed. Birth weight was also lower in girls than in boys, in newborns delivered at home rather than in a health facility, and in babies with a younger gestational age. Conclusion: Maternal exposure to IPV during pregnancy was associated with lower baby birth weights. Antenatal clinics should consider routinely identifying IPV-exposed women, and identifying babies with lower birth weights at home is an important indicator. The study was conducted in the Wondo Genet district located in the former Sidama zone of the Southern Nations, Nationalities, and Peoples Region (SNNPR). Based on the 2007 census and an annual population growth rate of 2.7% (21), the district’s projected total population in 2017 was 200 078. The number of women of reproductive age was estimated to be 46 618 with 6 923 expected pregnancies in a year. Wondo Genet district has a high population density and ethnic diversity. The district has three urban and 12 rural kebeles (Kebele is the smallest administrative unit in Ethiopia). There are 16 health posts and five health centers serving the population. The nearest hospital is in a neighboring district. Among the pregnant women attending antenatal care, 88% had four visits in 2016; only 10% of women in this area delivered at home (Wondo Genet district health office report, 2017). The 2016 Ethiopian DHS indicated that around 69% of women attended antenatal care at least once during their last pregnancy and institutional delivery was 26% in the region (SNNPR). Among women who delivered their most recent live birth in a health facility, 53% of them stayed in the facility for up to 11 h following vaginal birth (16). In this study area, women are often discharged from health facilities 6 h after a normal delivery. This was a community-based prospective cohort study investigating IPV. It was conducted between February and December 2017 among pregnant women who were enrolled at gestational age 25–34 weeks as listed by health extension workers (22) in two urban and three rural kebeles of the Wondo Genet district. The mothers and their babies were visited at home. We excluded twins and mother–baby pairs with late (i.e., invalid) birth weight measurements. In this article, we focused on IPV and its association with birth weight. The sample size to investigate the association between IPV and birth weight was calculated using OpenEpi version 3.03 software (23). The total sample size was estimated to be at least 435 based on an average birth weight of 3,000 g among unexposed and 2,850 g among exposed, with standard deviations of 423 g and 450 g, a ratio of unexposed to exposed of 4:1 (20), 80% statistical power, and 95% confidence level. The present work was part of a larger project (20) that required a sample size larger than this, so the sample size requirement for this study was met. Pregnant women living in the selected kebeles were enrolled through home visits. The sites were identified as being “urban” or “rural” according to the Ethiopian DHS definition of these terms (16). The selection of kebeles was decided based on the number of pregnant women in the areas as reported by the health extension workers. Pregnant women who fulfilled the inclusion criteria were consecutively enrolled in the study until the required sample size was obtained. The main outcome variable was birth weight measured in grams. The main exposure variable for this study was IPV during pregnancy, assessed in a home visit at enrollment using questions adapted from the WHO multi-country study questionnaire on women’s health and domestic violence against women (24). In the present study, IPV exposure in “the past 12 months” in the WHO study was changed to “during this pregnancy.” IPV was classified as being physical, sexual, or emotional. The respondents were given examples of physical violence including: partner had slapped or thrown something at her that could hurt her, pushed or shoved her, hit her with fist or something else that could hurt her, kicked, dragged or beaten her up, choked or burnt her on purpose, threatened to use or actually used a gun, knife, or other weapon against her. Examples of sexual violence included: partner had physically forced her to have sexual intercourse when she did not want to, had sexual intercourse when she did not want to because she was afraid of what her partner might do, and had forced her to do something sexual that she found degrading or humiliating. Examples of emotional violence included: partner had insulted her or made her feel bad about herself, had belittled or humiliated her in front of other people, had done things to scare or intimidate her on purpose, and had threatened to hurt someone she cared about. If the woman had experienced any of the three types of violence defined above, she was categorized as “IPV exposed.” Other covariates included the mother’s age (years), educational status of the mother and her partner (no education/primary/secondary and above), monthly income (Ethiopian Birr), residence (rural/urban), prior history of preterm birth and stillbirth (no/yes), antenatal care at least one visit (no/yes), smoking (no/yes), and regular alcohol use (no/yes) by participants or their partner. The Edinburgh Postnatal Depression Scale (EPDS) was used to measure maternal depression (25), and has been validated by previous studies in Ethiopia (26). Each of the 10 items in the EPDS has scores of 0–3; giving a maximum score of 30. Maternal depression was measured as a continuous variable with an EPDS score; we defined depression in this analysis as an EPDS score of 13 or more (27). A Maternity Social Support Scale with six items was used to measure social support. Each item has a score of 1–5, and the total score ranges from 6 to 30. Social support was categorized as low (score 0–18), medium (score 19–24), and high (score > 24) (28). Maternal malnutrition was assessed by mid-upper arm circumference (MUAC) and was measured in centimeters; undernutrition was set at MUAC <23 cm. The sex of the newborn (male/female/unknown) and its birth order (first/second and above) were recorded. The data were collected between February and December 2017. The data used to achieve the objectives of the present study are the same as described for the previously mentioned survey of IPV in the study area (20), with the same baseline data. We added follow-up data on birth characteristics, such as time of birth; whether the birth was live or not; sex of the newborn, and birth weight collected at a home visit as soon as possible within 72 h (time after delivery was noted for each participant). We collected data on selected variables that could be potential confounders. The main exposure variables were collected by trained data collectors using a structured and pretested questionnaire. The exposure status was determined based on the survey data from the baseline study. Birth weight was measured using a digital baby scale (Beurer BY 80), and the reliability of the scale was routinely checked by regularly measuring something of known weight. The mid-upper arm circumference (MUAC) was measured using a centimeter tape at the midpoint between the shoulder and elbow with the arm hanging down at the side relaxed. A MUAC below 23 cm defined a participant as being “malnourished.” The woman was asked for the date of her last menstrual period, which was used to calculate gestational age. When the exact date was unknown, the mother was asked to provide the alleged month. The field assistants actively sought out the women in person to check for delivery. They also used mobile phones. In addition, they were notified through mobile phone by the 1-to-5 network leaders as well as by the participants themselves, so that they recorded the exact date and time of birth for all births, whether they took place at home or at a health facility. The field assistants measured birth weight using a digital scale as soon as possible after delivery according to the operating instructions. They also recorded whether it was a live birth or stillbirth. Based on the last menstrual period, the principal investigator later determined whether the birth was term or not. Data were analyzed using SPSS version 20 (Armonk, NY: IBM Corp. USA) software. Chi-square and Fisher's exact tests were used to compare categorical variables. Mean values were compared using t-tests and analyses of variance. Multiple linear regression was performed to investigate the association between birth weight and maternal exposure to IPV during pregnancy (shown in Table 3). Other selected determinants were also studied. Preliminary analyses ensured that there was no violation of the assumption of normality, linearity, multicollinearity, and homoscedasticity. Complete case analysis was used for missing values to minimize potential bias. Variables having a correlation with birth weight at p < 0.2 levels and socio-economic and demographic variables were entered in the adjusted regression model. Maternal age, MUAC, and monthly income were entered as continuous variables. An adjusted regression coefficient (B) with a 95% confidence interval was reported. A p-value was considered statistically significant when < 0.05. Sensitivity analysis was also performed in a group of neonates whose birth weights were taken within the first 48 h after birth. We also analyzed risk factors for LBW (birth weight < 2,500 g) using logistic regression analysis (data not presented in a table). The study was conducted after obtaining approval from the Institutional Review Board (IRB) at the College of Medicine and Health Sciences, Hawassa University (Ref No: IRB/006/09) and regional ethical committee of Western Norway (Ref No: 2016/1908/REK vest). Permission from the parents as well as assent was obtained for those <18 years. In this setting, written consent was not culturally acceptable, but participants were comfortable with oral consent. Informed oral consent was obtained from each participant >18 years and recorded by the interviewer, according to the protocol approved by IRB. The study followed the ethical and safety guidelines recommended by the World Health Organization (29). All women who participated in the study were given information about the psychological and legal support available and how access could be provided if needed. This support would be paid for by the study project.