Study design and period
A community based cross-sectional study was conducted to examine the prevalence and associated factors of exclusive breastfeeding practice among mothers who had infants aged between 6 and 12 months, from 1 March to 20 March 20 2016.
Study setting and participants
The study was conducted in Gozamin district, located 300 km northwest of Addis Ababa, the capital of Ethiopia. The district has 30 kebeles (lowest local administrative units). The district has a total population of 153, 151 of whom 30, 982 are women in the reproductive age group (15–49 years). There also 20,743 under-five age children and 4769 infants less than one year of age. The district has six health centers and 26 health posts that provide health services to the community .
Sample size, sampling technique, and procedures
The single population proportion formula was used to determine sample size, assuming a 95% of confidence level, 5% margin of error, and 29% prevalence of exclusive breastfeeding . As we have used two stage sampling, a design effect of 1.5 is considered in determining the sample size. Finally, a contingency of 10% was used to account for non-response during data collection. Therefore, the final sample size was estimated to be 506 mother-infant pairs.
Among the 30 kebeles in the district, seven were selected using the simple random sampling technique to achieve the primary sampling units. The total sample size was allocated to the seven kebeles proportionally, based on the number of mother-infant pairs in each kebeles received from the district health office. Sample mother-infant pairs were selected using the systematic random sampling technique with a sampling interval of three. In order to source infants eligible for the study, we moved from village to village of each selected kebeles, assessing each and every household. Out of the first three households with infants eligible for the study, the second household was selected randomly as a random start. Then, out of households with infants aged between 6 and 12 months, every three mother-infant pair were included in the sample.
Data collection and quality control
Data were collected using interviewer administered structured questionnaire which was designed to assess EBF practice and associated factors. Each mother with an infant aged between 6 and 12 months was interviewed in order to get data regarding EBF practice and factors associated with it. The questionnaire included socioeconomic, obstetric, health, and health service related characteristics.
In order to maintain the quality of data, the questionnaire was translated from English to Amharic and back to English for consistency. Training that included field practice was given to data collectors and supervisors in kebeles which were not included in the main study. On-site supervision was carried out by the investigators and supervisors, and feedback was given.
Variables and operational definitions
The dependent variable of the current study is exclusive breastfeeding, and an infant fed only breast milk except taking vitamins, mineral supplements, or medicines until six months  was included as exclusive breastfeeding. Infants who had received exclusive breastfeeding correctly were coded ‘1’ in the SPSS during analysis, while those that had not been EBF correctly were coded ‘0’.
The independent variables considered in this study include maternal age, marital status, maternal education, maternal occupation, monthly family income, antenatal care, breastfeeding counseling, place and mode of delivery, and HIV status of mothers.
Maternal age was categorized into four groups (≤ 24, 25–29, 30–34, and ≥35 years), and the younger age was taken as a reference category in the logistic regression analysis. Marital status single was coded ‘0’ and married/union was coded as ‘1’. Maternal education ‘1’ was the code for mothers who were non-educated or who attended informal education and the rest were coded as ‘0’. Housewife mothers were coded as ‘1’ and government and private workers were encoded as ‘0’. Family monthly income was categorized into five levels, and the lowest level was taken as a reference category. Place of delivery was categorized into three (at home, government hospital, and health center), mothers who delivered at home were coded as ‘1’, the rest were encoded as ‘0’. Mothers who attended antenatal care, received breastfeeding counseling services, and had breastfeeding experience were coded as ‘1’ and their respective counterparts were coded as ‘0’. Mothers with Human Immunodeficiency Virus (HIV) positive mothers were coded as ‘0’ and HIV negative mothers as ‘1’. A health post is the lowest health facility structure in Ethiopian health tier system.
Data were entered, coded and cleaned, using Epi-info version 7.0 statistical software and then transferred to SPSS software version 20 for further data processing and analysis. Text descriptions, tables, charts, and graphs were used to describe the relevant findings of the study.
The Crude Odds Ratios (COR) with a 95% confidence interval (CI) were estimated in the binary logistic regression analysis to assess the association between each independent variable and the outcome variable, and to select candidate variables for the multivariate logistic regression analysis. Because there were relatively a large number of independent variables considered in this study, we had to screen them using the bivariate logistic regression to minimize the chance of multicollinearity in the multivariate logistic regression. Thus, only those independent variables with a p - values of 0.20 or less in the bivariate logistic regression were included in the multivariate logistic regression to get the adjusted effect of each covariate .
Adjusted Odds Ratio with a 95% confidence interval were estimated to assess the strength of the association. Variables with p - value less than 0.05 in the multivariate logistic regression analysis were considered as significant and independent predictors of exclusive breastfeeding practice.