Effect of nutrition education integrating the health belief model and theory of planned behavior on dietary diversity of pregnant women in Southeast Ethiopia: a cluster randomized controlled trial

A community-based, two-arm, parallel cluster randomized controlled trial study was used among pregnant women attending antenatal care at health facilities in Robe and Goba Towns, Bale Zone, Southeast Ethiopia, from February to December 2021. Robe and Goba Towns were located 430 and 444 km away from Addis Ababa, Ethiopia, respectively. There are 4 hospitals, namely Goba Referral Hospital, Robe, Delomena, and Ginnir; 87 health centers, and more than 300 health posts in the Bale Zone. There were 1,832 and 2,048 pregnant women in the towns of Goba and Robe, respectively. Cluster randomization was used over individual-level randomization to reduce contamination and for pragmatic reasons, as urban health extension workers (UHEWs) operate in clusters [23].

All pregnant women receiving ANC in the towns of Robe and Goba in the Bale Zone were source populations. All first- and early-second-trimester pregnant women who visited ANC clinics in the Robe and Goba Towns, in the Bale Zone, were the study population. First-trimester pregnant women who resided permanently in the study areas were included in the study. Pregnant women who had been diagnosed with HTN, or diabetes mellitus, were excluded from the study.

The sample size was determined using the G-Power software version 3.1, assuming an effect size of 0.25, a 95% confidence level, a precision of 0.05, and a power (1- β) of 80% [24]. The computed sample size was 206. Taking the largest sample size and considering the design effect (DE) of 2 and the 10% attrition rate, the final sample size was 454 (intervention group = 227 and control group = 227).

Two towns, namely, Robe and Goba, were selected. Robe town has three kebeles (the smallest administrative unit) (Baha Biftu, Donsa, and Oda Robe), whereas Goba Town has an Eastern and Western kebeles. The number of pregnant women in each cluster was determined using birth data prepared by UHEWs. Clusters were randomized to the intervention and control groups randomly. Pregnant women in Robe Town received nutrition education, while those in the Goba town control group did not. The sample size was allocated to each cluster by probability proportional to size (PPS). A multistage cluster sampling technique was used to select the pregnant women. The sample size was allocated to each cluster by probability proportional to size (PPS). Pregnant women were selected using a systematic sampling technique. If a woman was absent from her house during the interview, eligible pregnant women in the next house in the serial number were interviewed. The house of the absent pregnant woman was revisited the next day. By asking about the first date of the last menstrual period and confirming pregnancy with a pregnancy test, gestational age was computed.

Pregnant women were assessed for eligibility and allocated randomly to the intervention and control groups using a 1:1 ratio. The allocation sequence was generated using coin tossing. A simple randomization approach, coin-tossing, was used to generate the allocation sequence. The local languages, Afan Oromo and Amharic, were used for communication during nutrition education. The intervention group received nutrition education, counseling cards, and a structured work schedule. The key messages for the lessons were created using the health belief model (HBM) and theory of planned behavior (TPB) theoretical principles [17, 25]. The HBM is an interpersonal health model that is used to foster positive behavior [26]. It explains why some people adopt health-promoting steps while others do not [17, 26]. Prediction of intention and behavior was also conducted using the TPB constructs [17, 25]. TPB was utilised to identify the psychological processes (behavior mediators) that lead to intervention results, both for assessment and to explain dietary behavior changes. The purpose of the study was not to test the theoretical model but to offer direction on the sorts of factors and processes that may be essential in influencing maternal health behaviors and should be addressed in the intervention. The intervention was intended to increase personal and normative nutrition actions [27] towards diverse diet sustenance as a consequence of good nutrition attitudes and behavior control. It was adapted on the recommendation of the Ministry of Health (MOH), Ethiopia [28]. Baseline and end-line assessments were made for two groups. After baseline data collection, pregnant women in the intervention received nutrition education every trimester consistently for six months (six sessions) after they were recruited at their homes in each cluster. Recruitment was done when animal-source foods (ASF) were allowed. Nutrition education was delivered for 30 to 45 min per session. The nutrition education and supervision processes took place with six nurses holding Bachelor of Science (BSc) degrees and two Master of Public Health (MPH) specialists, respectively.

The core content of the session was: increasing knowledge about essential nutrition actions (ENA), iron-rich food sources to improve Hgb, iron-folate acid supplementations (IFAS), iodized salt, meal frequency, and portion size with increasing gestational age; dietary diversifications: food groups; iron absorption enhancers and inhibitors; reducing heavy workloads, taking days off, exercising, increasing utilization of health services, and interrupting the intergenerational life cycle of malnutrition; increase pregnant women’s perceptions of under nutrition and factors leading to it, poor eating practices causing inadequate dietary intake and disease; gestational weight gain, birth weight, food security, a food-based approach; dietary modification; increasing knowledge about FV consumption through diversification, enrichment, and standardization; identifying barriers and ways to overcome them; decreasing the perceived barriers to preparing a FV; encouraging participants to identify ways to overcome the barriers; specific food taboos (meat and eggs); increasing knowledge and attitudes about pregnant women’s ability to modify feeding practices; improving participants’ perceptions of control and intention; and improving participants’ skills in washing hands.

Presentation, discussion, demonstration, and picture-based activities were used to deliver counselling. Compliance was examined using observation, self-report, and attendance. Second-degree public health specialists led the counselling session. Trainers monitored compliance with regards to observation and attendance. They identified critical counseling skills, key messages, feasible activities, and the GALIDRAA (greet, ask, listen, identify, discuss, recommend, agree, set follow-up appointment) processes. Intervention and control groups received nutrition education routinely from nurses. However, due to the unique characteristics of the cluster RCT and the nature of the intervention under research, no concealment was used in the study. This study was not blinded, as the two towns were far apart from each other (more than 10 km). Counseling was not administered by the same nurses to avoid information contamination between intervention and control.

Pregnant women were aware of the intervention; however, pregnant women in both arms were blinded to the research hypotheses. Once the women were enrolled, reasonable efforts were made to promote their retention and complete follow-up by offering soaps to them to minimize missing data. Interest in the study was also maintained through periodic discussions concerning compliance with the intervention during regular meetings as well as home visits by trainers. Furthermore, home visits were scheduled to reduce the pregnant women’s burden associated with follow-up visits. Monitoring and evaluation of the activities were done by the lead author and supervisors.

The control groups were not given a specific schedule. Nevertheless, they received standard healthcare. The control group received a brief intervention at the end of the study to ensure justice and obtain a high degree of post-recruitment satisfaction. In Ethiopia, the MOH’s routine health extension programme packages have 16 components consisting of: family health (family planning, maternal and child health, nutrition, and vaccination services), disease prevention and control (HIV/AIDS and STIs, tuberculosis, malaria, and first aid cares), hygiene and sanitation (promotion of sanitary latrines, waste disposal management, water supply, food hygiene and safety, control of insects and rodents, personal hygiene, and healthy home environment services), and health education [29].

An interviewer-administered, structured questionnaire was used to collect the data. The data collection tools were adapted from the Ethiopian Demographic and Health Survey (EDHS) and existing literature [3, 18, 30]. Data on socio-demographic and economic factors, substance abuse (tea or coffee, alcohol, smoking), and reproductive history were collected before the intervention. Nutritional, intimate partner violence (IPV), physical exercise, health care delivery systems, knowledge and practice of HBM, and TPB tools were collected before and after intervention. End-line data were collected at the end of 36 weeks of gestation.

The principal component analysis (PCA) was used to generate a wealth index. Twenty-one variables entered into the PCA included the availability of a water source, a latrine, a bank account, different types of living houses, livestock, agricultural ownership, and household asset items [31, 32]. The responses of all non-dummy variables were dichotomized as “improved” (= 1) and “unimproved” (= 0) based on the WHO/UNICEF definition. Household income was classified into tertiles: “high,” “medium,” and “poor” [33]. Finally, the highest tertile was designated as having a high income, while the two lowest tertiles were designated as having a low income.

Assumptions of PCA include the correlation matrix for the variables containing two or more correlations ≥ 0.30; variables with measures of sampling adequacy less than 0.50 that must be removed (looking anti-image); the overall measures of sampling adequacy, Kaiser-Meyer-Olkin (KMO) ≥ 0.5 [34], the Bartlett test of sphericity (p-value < 0.05); communality > 0.5; and not having the complex structure of correlation ≥ 0.40. Components that collectively explain more than 60% of the variance in the set of variables and have eigenvalues ≥ 1 [35, 36] were used to identify variables to be included in further analyses. Then, the economic status of study subjects was categorized into tertiles as rich, medium, and poor. The highest tertile was used to designate a more wealth lifestyle, while the two lowest tertiles were used to represent a less wealthy lifestyle.

The status of household food security was evaluated using 27 previously validated questions. Food secure, mildly, moderately, and severely food insecure families were defined as having fewer than the first two, two to ten, eleven to seventeen, and more than seventeen food insecurity indicators, respectively [37].

Each HBM was assessed using the sums of a 5-point Likert scale (1 = strongly disagree to 5 = strongly agree) to form a composite question: perceived susceptibility (3 items), perceived severity, and perceived benefits (4 items each), perceived barriers (5 items), cues to action, and self-efficacy (4 items each) [25]. TPB constructs: attitude and subjective norms (3 items each), perceived behavioral control (2 items), and behavioral intention (2 items) (7 items) [38]. The factor scores were summed and categorized into tertiles, and the highest tertile was labelled as having a “yes” for perceived susceptibility, severity, benefit, barriers, cues to action, self-efficacy, positive attitude, perceived behavioral control, and behavioral intention; otherwise, the two lower tertiles were labelled as “no.” A ten-item knowledge questions was also used to measure the significance of fruits and vegetables [39]. If a respondent answered correctly, they received a 1; otherwise, they received a 0. After that, the scores were computed and ranked in tercile order. Finally, the highest tertile was labeled with a high level of nutrition knowledge, while the two lower tertiles were labeled with a poor level of nutrition knowledge.

An epidemiologist and a biostatistician reviewed the completed questionnaire to ensure its validity. Finally, we modified the questionnaire based on the findings of the pre-test and specialty reviews (setting and wording questions, sequencing, formatting, and scaling responses). The training was given to eight nurses with BSc degrees as data collectors and four MPH specialists as supervisors on the objectives of the study, data collection instruments, and ethical issues to minimize interviewers’ bias. Six counselors were trained by the lead author. A lead author met with counselors every two weeks to discuss ways of improving the counseling session process.

Supervisors closely followed the data collectors daily for the successful completion of the questionnaire and took timely action in case of any deviations. The study participants were interviewed at their homes to improve the response rate. The internal consistency of the cognitive, affective, and psychomotor domains of the tools were assessed using Cronbach’s alpha (Table S1).

The dietary diversity score (DDS) was the primary outcome variable. A 24-hour qualitative dietary recall method was used to calculate the DDS. The DDS for women is a nine-food group to indicate a qualitative indicator of micronutrient sufficiency in a diet [40]. The score was calculated using nine food classes in order to indicate the diet’s micronutrient sufficiency. Participants were asked to recall everything they had eaten and drunk in the previous 24 h, both inside and outside their homes.

Participants were also asked to recall any snacks they had had in between big meals. Consumption of a food item during the reference period was assigned a score of “1,” whereas non-consumption was assigned a score of “0.” The foods were then classified into nine groups: (1) starchy staples; (2) dark green leafy vegetables; (3) vitamin-A-rich fruits and vegetables; (4) other fruits and vegetables; (5) beans, nuts, and seeds; (6) meat and fish; (7) fats and oils; (8) milk and milk products; and (9) eggs. The DDS was calculated by adding the food groups consumed during the reference period and ranking them into tertiles, with the highest tertile indicating a high DDS (= 1) and the two lower tertiles combined representing a low DDS (= 0) [41].

The data were checked for completeness, consistency, and accuracy and entered into, cleaned, and analyzed using SPSS for Windows version 20 and Stata version 14. Descriptive statistics, including frequencies, percentages, means, and standard deviations, were generated for the selected predictors. The baseline characteristics of the intervention and control groups were assessed using the chi-square test. The McNemar test was used to compare DDS within the intervention and control groups. The difference in difference (DID) analyses were used to estimate DDS between the two study arms [42].

Variables with a p-value less than 0.25 in a bivariable generalized estimating equations (GEE) binary logistic model were entered into a multivariable GEE binary logistic model to account for within-cluster correlation of measurements. GEE can manage missing data values without the need for explicit imputation by considering all study subjects with at least one follow-up visit and automatically removing the missing values via the GEE analysis model [43].