1 Introduction

Low birth weight (LBW) is associated with impaired cognitive development, fetal and neonatal morbidity and mortality and the advent of chronic diseases in later life [1]. LBW is defined by the World Health Organisation (WHO) as birth weight < 2500 g [2]. Fetal weight at birth is directly related to the health and nutrition of the mother [4,5,6]. Timely medical care, adequate nutrition and sufficient education to make informed choices on behalf of her unborn child are important to avoid LBW [7].

Knowledge of the mother related to LBW is a vital factor to prevent LBW and to reduce the prevalence of LBW. Studies have shown by increasing the knowledge of the mother, the birth of LBW babies can be prevented [8,9,10]. Parent-based interventions and early education programmes are the common types of interventions for LBW infants [11]. It has been found that among father-absent births, there are higher rates of LBW, very low birth weight (VLBW), preterm birth, very preterm birth, and small for gestational age (SGA) [12, 13].

In improving the well-being of people, health promotion is a cost-effective approach which WHO has recognised. The health promotion approach involves lay people in each step of the health promotion process [14]. The laypeople identify and address determinants of a specific problem or concern [15].

The main objective of this study was to implement and evaluate the effectiveness of a community-based health promotion intervention aimed at increasing pregnant mothers and their partners' knowledge regarding birth weight and its determinants. The secondary objective was to evaluate the difference of the Birth weight by implementing the intervention. The study specifically aimed to assess antenatal couples' knowledge on various topics, such as fetal growth and the consequences of impaired fetal growth, expected birth weight and its determinants, expected weight gain of pregnant mothers, nutrition of pregnant mothers, and methods to stimulate the fetus.

To improve knowledge on these topics, the intervention was designed, and its effectiveness was evaluated using a quasi-experimental design by comparing the knowledge levels of the intervention and control groups.

2 Methods

This quasi-experimental study was implemented using 806 pregnant mothers. Of the participant pregnant mothers in both groups, a majority were legally or customarily married and only less than 1% were unmarried (IG; n = 2/397, CG; n = 3/387). There were no pregnant mothers who were divorced, separated or widowed. It was carried out in Anuradhapura District [Intervention Group (IG), 403 mothers] and Polonnaruwa District [Comparison Group (CG), 403 mothers). The pre and post-evaluation was done for both IG and CG groups. The comparison was done within the group and between groups for pre and post-separation. Since they have similar socio-demographic features these two districts were selected as the IG and CG groups. To avoid contamination two different districts of the same province were selected.

The mothers were recruited from participants registered with routine field antenatal services/clinics (ANC) in three selected Medical Officer of Health (MOH) areas, each from the two districts. Pregnant mothers who were registered in the ANC before 12 weeks of period of amenorrhea (POA) were included in the study. The IG consisted of 19 MOH areas, while the CG consisted of 7 MOH areas. Out of these for both IG and CG, 7 MOH areas were compared and paired, out of which three were randomly selected. Of the pregnant mothers, partners were recruited from both IG and CG.

2.1 Sample size and sampling technique

The sample size was calculated using the following formula based on the expected LBW prevalence rates as LBW was the main outcome indicator for the intervention [16].

$$\text{n}=\text{n}_1=\text{n}_2=\frac{P_1 \left(100 -P_1\right)+P_2 \left(100 -P_2\right)}{\left(P_1 -P_2\right)^2}\times f(\alpha ,\beta )$$

The sample size of each MOH area in the IG was 196, 127 and 80, each with 10, 9 and 7 ANCs, respectively, which were also randomly selected. Likewise, the sample size of each MOH area in the IG was 177, 127 and 99, each with 7, 15 and 6 ANCs, respectively. Thus, the IG comprised 26 ANCs, and the CG comprised 28 ANCs with a sample size of 403 each.

In 26 ANCs, twenty-six initial training sessions were conducted as a group, with an average of three hours for each session. Three follow-up sessions were conducted in each ANC over 04 months (in total 104 sessions). All sessions were conducted in groups of 10–20 antenatal couples. Couples' attendance for the initial session and the final follow-up was encouraged by public health midwives. The regular attendance of mothers was good when compared to their partners. During the initial session, some partners expressed their inability to attend the meetings in person due to their work commitments. However, they agreed to participate remotely through telephone or WhatsApp, relying on their spouses to convey the information. Those who attended the sessions acted as agents, disseminating knowledge to their partners and other mothers, thereby ensuring the continuity of knowledge transfer. At the end of each session, the facilitators provided a summary of the main points to be shared with those unable to attend. Each session was an average of 3 h.

Structured and semi-structured interviews and observations were used to assess knowledge. Interviewer-administered questionnaires were of two types developed to obtain data on the following among pregnant mothers and their partners. (a). Knowledge on growth and development of a fetus where, a consequence of growth retardation, ways of monitoring and stimulation of intra-uterine development were addressed. (b). Knowledge of LBW and its determinants was addressed through knowledge of expected birth weight, expected maternal weight gain, determinants of LBW and maternal body mass index (BMI) and nutrition (adequacy, quality, available food types).

The discussions were not only as lectures; appropriate videos and simple examples in a language they can understand were used. In each discussion, they were first asked what they currently knew of the discussed topic, and then they were facilitated on what they were supposed to know. Thus, a people-centered learning teaching method with a participatory approach was used for the intervention to increase the knowledge of the lay community.

The importance of the first 1000 days in an individual’s life in determining his/her potential and health was further explained as the path to achieve the parents’ dream for their child. How the first 280 days or the antenatal period influences a child’s life was extensively discussed in order to make mothers understand the importance of the antenatal period in determining her child’s life. At this stage, discussion was directed to examining underlying factors as a step in improving birth weight. Thereafter, how determinants operate at individual, household, and community levels were explained. This was the first session conducted during this process, and was used also to engage with the participants.

The lecture discussions were initiated with discussions about the mother’s vision or dream about the child to be born. Thereafter, the understanding or hopes for the future of the pregnant mothers on their baby to be born was broadened by the facilitator. The relevance of good birth weight to achieving this goal was also discussed. That the future vision for the baby to be born should not only be of the mother but also of the father was discussed.

Two tools were developed by the community themselves after facilitation and utilized, one for the mother and one for the partner (father), which consists of two sections. The knowledge received by the mothers was assessed using structured and semi-structured interviews and observations. To determine the birth weight, data from the Public Health Midwife’s records and Birth weight recorded in the Child Health Development Record were used. Collecting data from their partners was done; if the partners were available at the first clinic visit; they were interviewed the same day after obtaining informed written consent. If they were not available on that day, appointments were made to interview them. The pre-and post-interventional mean scores for both IG and CG within-group and between-group comparisons have been done using percentage, SD, mean, McNemar’s Chi-Square test; Chi-Square test, Fisher’s Exact test, Paired t-test, Student’s independent sample t-test, Wilcoxon Signed Ranks test and Mann–Whitney U test methods were applied as appropriate.

3 Results

The knowledge about fetal growth of pregnant mothers was assessed using four indicators; Foetus growth and gain of weight, Foetus’ brain development, Foetus’ growth can be monitored by measuring the mother’s weight and Foetus’ growth can be monitored by measuring simphysio-fundal height.

The pre-intervention for between groups in CG and IG both shows that in all the components assessed on fetal growth, IG had a significantly higher proportion of mothers who provided correct responses compared to the CG (Table 1).

Table 1 Comparison of proportion of participants with correct responses on foetal growth in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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For pre-intervention, the partners show that, in all the components assessed on fetal growth, IG had a significantly higher proportion of partners who provided correct responses compared to CG (Table 2). The proportion of partners who knew methods to monitor fetal growth was less than 10% in both groups (IG—9.9%, n = 32; 7.7%, n = 25; CG—4.1% n = 12; 3.8%, n = 11). In the post-intervention, IG had a significantly higher proportion of partners who provided correct responses compared to the CG in all indicators.

Table 2 Comparison of proportion of partners with correct responses on foetal growth in the intervention (IG) and comparison (CG) groups in the pre and post assessments
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The knowledge on consequences of impaired fetal growth of pregnant mothers in the post-intervention IG group reported proportions of correct responses higher than 85% in all indicators (Table 3). They were significantly higher (p < 0.001) than the proportions reported by the CG which is 55–79%.

Table 3 Comparison of proportions of participants with correct responses on consequences of impaired foetal growth in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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When considering the between-group comparison, for pre-intervention, the highest proportion of pregnant women in both intervention (74.0%, n = 257) and the comparison (64.0%, n = 217) groups got the correct response on “Intellectual deficiencies” and the difference was statistically significant (X2 = 8.943 df = 1; p = 0.003). The second highest correct responses were for low birth weight (IG; 73.8%, n = 256 and CG; 52.8%, n = 179; X2 = 8.943 df = 1; p = 0.003; Table 3). In the post-intervention, IG group reported proportions of correct responses higher than 85% in all indicators and they were significantly higher (p < 0.001) than the proportions reported by the CG.

The knowledge of the consequences of impaired fetal growth of partners in the post-intervention IG group reported proportions of correct responses higher than 80% in all indicators (Table 4). They were significantly higher (p < 0.001) than the proportions reported by the CG which is 45–75%.

Table 4 Comparison of proportions of partners with correct responses on consequences of impaired foetal growth in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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For knowledge of the expected birth weight of pregnant mothers (Table 5), both proportions improved significantly in the post-assessment (71.5%, n = 248, p = 0.015 and 72.3%, n = 245, p < 0.001). In partners (Table 6), only less than 20% (IG—18.9%, n = 61; CG—8.9%, n = 26) knew the expected weight of a new-born (X2 = 14.988; df = 1; p < 0.001) in the pre-intervention assessment. Both proportions improved significantly in the post-assessment, but the proportion of the CG remained less than 20% (14.3%, n = 42, X2 = 44.713 df = 1; p < 0.001).

Table 5 Comparison of proportions of participants with correct responses on expected birth weight in the intervention (IG) and comparison (CG) groups in the pre and post assessments
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Table 6 Comparison of proportions of partners with correct responses on expected birth weight in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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The Between group comparison: pre-intervention (Table 7, Supplementary 1) highest proportion of correct response were for maternal nutrition (IG; 90.8%, n = 315 and CG; 93.2%, n = 316), maternal rest (IG; 70.3%, n = 244 and CG; 68.4%, n = 232; Table 7) and maternal mental wellbeing (IG; 75.8%, n = 263 and CG; 82.6%, n = 280). Except for the maternal mental well-being, in which the CG reported a higher proportion of correct responses (X2 = 5.252; df = 1; p = 0.022), the above-mentioned indicators showed no significant difference in the proportions of correct responses in the two groups. However, in all the other indicators, the IG reported a significantly higher (p < 0.001) proportion of correct responses, except for the indicator “indoor air pollution”.

Table 7 Comparison of proportions of participants with correct responses on their own pre-pregnancy BMI and expected weight gain during pregnancy in the intervention (IG) and comparison (CG) groups in the pre and post assessments
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Post-intervention: IG reported more than 80% correct responses in all the indicators, whereas CG did only for the above-mentioned indicators (maternal nutrition, maternal rest and maternal mental wellbeing). For those indicators, less than 10 participants got incorrect responses in the IG. Proportions of correct responses in the IG were significantly higher (p < 0.001) than the proportions reported by the CG in all indicators.

Supplementary 1: Comparison of proportions of participants with correct responses on determinants of low birth weight in the intervention (IG) and comparison (CG) groups in the pre and post-assessments. (Supplementary 1).

For the correct responses on determinants of low birth weight, the between-group comparison for pre-intervention: IG reported significantly higher proportions of correct responses in all indicators, except for ‘maternal nutrition’, the indicator with the highest proportion of correct responses in both groups (IG—95.1%, n = 307; CG—93.4%, n = 274; X2 = 0.84 df = 1; p = 0.359; Supplementary 2). Lowest was reported for ‘pre-pregnancy BMI’ in the IG (33.9%, n = 109), and ‘indoor air pollution’ in the CG (16.2%, n = 47).

Post-intervention: IG reported more than 80% correct responses in all indicators, except for ‘indoor air pollution’ (68.9%, n = 223), for which, CG reported only 43.0% (n = 126). IG had significantly higher proportions in all the indicators except for the ‘maternal nutrition’ (X2 = 0.139 df = 1; p = 0.709).

Supplementary 2: Comparison of partners giving correct responses on determinants of low birth weight in the intervention (IG) and comparison (CG) groups in the pre-and post. (Supplementary 2).

Knowledge improvement of determinants of LBW of pregnant mothers with lower knowledge (< 3/10 correct responses) in the pre-intervention assessment, IG (n = 46) reported a post-intervention mean value of 9.0 (SD = 2.1) and CG (n = 89) reported a mean of 4.9 (SD = 2.7), the difference was significant (t = 11.139, p < 0.001).

Knowledge improvement of determinants of LBW of partners with lower knowledge (< 3/10 correct responses) in the pre-intervention assessment IG (n = 40) reported a post-intervention mean value of 8.4 (SD = 3.5) and CG (n = 95) reported a mean of 4.0 (SD = 3.1), the difference was significant (t = 7.203, p < 0.001).

The knowledge on expected maternal weight gain of pregnant mothers (Table 7) was less than 25% of pregnant mothers knew their own BMI and expected weight gain correctly in both areas. Even though the proportions significantly improved post-intervention, they remained low compared to other knowledge indicators. For the partners, 26.3% (n = 85) in the IG and 8.2% (n = 24) in the CG knew the pre-pregnant BMI of the pregnant mothers in the pre-intervention.

Of the partners, 26.3% (n = 85) in the IG and 8.2% (n = 24) in the CG knew the pre-pregnant BMI of the pregnant woman in the pre-intervention (Table 8). Proportions of both groups improved significantly in the post-intervention assessment and it increased above 50% (51.7%, n = 167) in the IG. Only 3.1% (n = 10) partners in the IG and 2.1% (n = 6) partners in the CG knew the expected weight gain correctly in the pre-intervention phase. The proportion improved significantly to 20.4% (n = 66) in the IG, whereas the proportion of CG remained less than 3% (2.7%, n = 8).

Table 8 Comparison of proportions of partners with correct responses on their wives’ pre-pregnancy BMI and expected weight gain during pregnancy in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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Comparison of proportions of participants with correct responses on ways to stimulate the foetus for between-group comparison: for pre-intervention: Significantly higher proportions (p < 0.001) of the IG reported correct responses for all indicators compared to the CG. For post-intervention: IG reported significantly higher (p < 0.001) proportions for all indicators ranging from 95.7% (332/347) to 98.0% (340/347), whereas the CG percentages only ranged from 53.7% (182/339) to 69.6% (236/339) (Table 9).

Table 9 Comparison of proportions of participants with correct responses on ways to stimulate the foetus in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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Within group comparison for Intervention group: Proportions of correct responses improved significantly in all indicators, with highest increase in singing lullabies (33.4%, n = 116). For the comparison group: Proportions of correct responses improved significantly in all indicators, with highest increase in talking to the foetus (26.9%, n = 91).

Comparison of proportions of partners with correct responses on ways to stimulate the foetus for between-group comparison in the pre-intervention shows significantly higher proportions (p < 0.001) of the IG-reported correct responses for all indicators compared to the CG (Table 10).

Table 10 Comparison of proportions of partners with correct responses on ways to stimulate the foetus in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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For the post-intervention, the IG reported more than 90% proportions for all indicators (97.2%, n = 314; 97.8%, n = 316 and 94.4%, n = 332). All were significantly higher (p < 0.001) than the CG (80.5%, n = 236; 77.1%, n = 226 and 75.4%, n = 221; Table 10). For the within-group comparison the proportions of correct responses improved significantly in all indicators, in both groups.

Making a pregnant mother’s room, interacting with nature (listening to birds, watching the night sky, taking walks in scenic surroundings and watching birds/animals) and telling or reading stories to the foetus were the commonest actions suggested by the IG. Reading books, eating a good quality diet and engaging in religious activities were the commonest actions suggested by the CG (Supplementary 3).

The most commonly mentioned other actions to stimulate the foetus in the post-intervention assessment for partners are given in (Supplementary 4).

Making a pregnant mother’s room, interacting with nature (listening to birds, watching the night sky, taking walks in scenic surroundings and watching birds/animals) and caressing the abdomen were the commonest actions suggested by the IG (Supplementary 4). Religious activities, eating a good quality diet and listening to “pirith” were the commonest actions suggested by the CG (Supplementary 4).

Knowledge on nutrition of partners for between-group comparison: in the pre-intervention: There was no significant difference between the proportions naming all the essential nutrient groups correctly (X2 = 0.162; df = 1; p = 0.687). Except for naming the two carbohydrate-rich food items, of which the CG reported a higher proportion (X2 = 8.318; df = 1; p = 0.006), all the other proportions were similar between the two groups. For the post-intervention: IG reported significantly higher (p < 0.001) proportions for all indicators except for naming two carbohydrates (p = 0.0511) and protein (p = 0.700) rich food items.

The within-group comparison for the intervention group: proportions of correct responses improved significantly in all indicators. For the comparison group: proportions correctly naming two carbohydrates (88.1% to 91.8%, p = 0.0511) and iron (23.5% to 21.8%) rich food items did not improve.

The knowledge on the nutrition of pregnant mothers for the between-group comparison: pre-intervention: of the participants, 72.3% (n = 251) in the IG and 66.1% (n = 224) in the CG named all nutrient groups correctly (X2 = 3.399 df = 1; p = 0.065). The highest proportion got food containing carbohydrates correctly in both groups (IG; 70.6%, n = 245 and CG; 78.5%, n = 266), (X2 = 6.857; df = 1; p = 0.009). The lowest was for the Vitamin A-rich food with IG reporting a significantly higher (X2 = 8.684; df = 1; p = 0.003) proportion (20.5%, n = 71) compared to the CG (10.0%, n = 34). In the Post-intervention: IG reported significantly higher (p < 0.001) proportions for all indicators except for carbohydrate (p = 0.521) and protein (p = 0.736) rich food items.

In the within-group comparison, for the intervention group: proportions of correct responses improved significantly in all indicators, even though they remained less than 50% in naming two iron (43.2%, n = 150) and Vitamin A (28.8%, n = 100) rich food items. In the comparison group: All proportions increased significantly except for naming two carbohydrate-rich food items, of which the proportion remained the same (78.5%, n = 266). Except for carbohydrate and protein-rich food items, the percentages reporting good knowledge was less than 50% for other categories.

For the primi mothers, except for birth weight and its determinants, IG showed higher rates in all the other indicators in the pre-assessment. The mean scores of all indicators improved significantly in the post-assessment, and the IG showed a higher mean increase in all indicators (Table 11).

Table 11 Comparison of mean knowledge scores of primi-parous pregnant women in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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When considering the pregnant mothers with lower (total score < 10) pre-assessment knowledge, the pre-intervention of both IG and CG reported similar median scores except for indicators for knowledge on maternal nutrition (p = 0.12) and fetal stimulation (p < 0.001), for which IG reported higher scores (Table 12). The median total score was also similar (IG; M = 9.0, IQR = 5–9, CG; M = 8.0, IQR = 6–9; p = 0.637). For the post-intervention, IG reported significantly higher (p < 0.001) median scores for all indicators except for indicators for knowledge of maternal nutrition (p = 0.681). The median total score of the IG (M = 27.5, IQR-25–28) for the assessed indicators doubled the median total score reported by the CG (M = 14; IQR-11–17; p = 0.002).

Table 12 Comparison of median scores of pregnant woman’s knowledge with a low pre-assessment score (< 10) in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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For within-group comparison the intervention group, median knowledge scores significantly improved in all indicators except for the indicator ‘stimulating the foetus’, for which the pre-assessment denoted the maximum score as the median. However, the IQR of the same changed from 1 to 3 to 3 to 3. Median total knowledge score tripled with 75% (N = 7) reporting a score higher than 25 (total = 30). However, it was not statistically significant (p = 0.066). The comparison group: median knowledge scores improved significantly in all indicators and for the total.

For the partners with lower pre-assessment knowledge (total score < 10) in the pre-intervention (Table 13), both reported similar median scores except for indicators for knowledge on foetal stimulation (p = 0.002), for which IG reported the maximum possible score, whereas CG reported 0. The median total score was also similar (IG; M = 9.0, IQR = 7–9, CG; M = 8.0, IQR = 7–9; p = 0.902). For the post-intervention, IG reported significantly higher (p = 0.012) median scores for all indicators except for indicators for knowledge of maternal nutrition, for which both groups reported the same median score (p = 0.977). The median total score of IG (M = 23.5; IQR-22–26) for the assessed indicators was significantly higher than the median total score reported by the CG (M = 15; IQR-13–22; p = 0.007).

Table 13 Comparison of mean scores of partners’ knowledge with a low pre-assessment score (< 10) in the intervention (IG) and comparison (CG) groups in the pre and post-assessments
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For the within-group comparison, Intervention group: Median knowledge scores significantly improved in all indicators except for the maternal nutrition-related indicators (M1 = 2, IQR = 1–3; M2 = 3.0, IQR = 2.5–4; p = 0.056). Median total knowledge score (23.5; IQR = 22–26) tripled (p = 0.012) compared to the pre-assessment score (8.0; IQR = 7–9). For the comparison group: median knowledge scores improved significantly in all indicators and for the total.

For the prevalence of low birth weight, IG reported a significantly lower (p < 0.001) LBW prevalence (10.0%, n = 37; Table 14).

Table 14 Comparison of prevalence of low birth weight in the intervention (IG) and comparison (CG) groups
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The mean birth weight reported in the IG (M = 2987.3; SD = 427.5; Table 15) was 215 g higher than the mean birth weight reported in the CG (M = 2772.4; SD = 408.0).

Table 15 Comparison of mean birth weight in the intervention (IG) and comparison (CG) groups
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Table 16 Intervention-related factors
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The mean birth weight shows that the IG has a mean BW of 3097.1 g while CG has 2727.9 g and is significant (p < 0.001) for mothers with low knowledge scores (< 50% of total). For the Partners with low knowledge score (< 50% of total) the IG has a mean BW of 2978.9 g and CG has 2753.4 g which is less significant (p = 0.013).

The intervention appears to have been effective in increasing knowledge about LBW and its determinants, with IG reporting higher increases in mean scores in all four major knowledge categories: (a) fetal development, consequences of impaired foetal growth and monitoring, (b) birth weight and determinants, (c) maternal nutrition and (d) ‘stimulating the fetus’. The pregnant mothers showed an increase in score of 6.5 (IG M2 25.8–IG M1 19.3) while CG was 4.8 (CG M2 19.9–CG M1 15.1). The partners in the IG showed 7.4 (IG M2 23.9–IG M1 16.5) for the same, while in the CG, it was 5.9 (CG M2 19.7–CG M1 13.8).

This difference of magnitude in knowledge scores of pregnant mothers was most visible about ‘fetal development, consequences of impaired fetal growth and monitoring’ (IG M2 8.0–IG M1 5.3; difference = 2.7) and ‘Birth weight and determinants’ (IG M2 10.4–IG M1 7.3; difference = 3.1). The difference of magnitude among partners was most visible about ‘fetal development, consequences of impaired fetal growth and monitoring’ IG M2 7.1–IG M1 4.2; difference = 2.9) and ‘Birth weight and determinants’ (IG M2 9.2–IG M1 6.3; difference = 2.9).

The most important achievement is the participants in IG who had a low knowledge level (less than 10 of a possible total score of 30) also reported higher post-assessment knowledge scores compared to the CG (mothers: IG; M = 27.5, IQR = 25–28; CG; M = 14, IQR = 11–17; p = 0.002 and partners: IG; M = 23.5, IQR = 22–26; CG; M = 15, IQR = 13–22; p = 0.007, demonstrating the ability of the developed model to improve knowledge among low performing groups.

4 Discussion

The assessment of all indicators used to increase the knowledge of pregnant mothers and their partners knowledge on all indicators has been improved significantly in both mothers and partners of the IG. This implies that the health promotion approach [17, 18], which engaged the lay community for the intervention, has successfully increased the knowledge of both mothers and partners to reduce LBW. Thus, the participatory approach of [3, 19], where the spiral model includes starting with people's own experience, looking for patterns, adding new information and theory, and practising skills, strategies and action plans, is successfully achieved when carrying out interventions with the rural communities to increase knowledge.

When provided with a little knowledge and using the intervention model with health promotion principles, lay communities were capable of identifying tools as well as determinates to address the issue and solve them by themselves.

Further, as for [20] the knowledge regarding the nutrition of pregnant mothers has been relatively low before the intervention and has shown that information about nutrition [6, 20], family income and the educational status of mothers has had a positive significant relation with mothers’ nutrition knowledge in the study area. The current study also has shown that in the Post-intervention, IG reported significantly higher (p < 0.001) proportions for almost all indicators. Therefore, increasing maternal nutrition knowledge is important in reducing the LBW.

Thus, the study reveals that the knowledge enhancement of the partners influences the improvement of LBW, as also shown by others [9, 21, 22]. In most cases, it has been difficult to get male participation [22, 23], and it is a problem since the partners do not receive the knowledge and, therefore, they do not know that they could contribute to making a difference in the weight of the child to be born [23]. This intervention accessed and engaged the partner and made them knowledgeable in the contribution they can make to ensure a good birth weight. This was mainly made possible by the mother communicating to the partner what she discussed with the facilitator. Thus, through the mother, it has been possible to get the partner involved in the intervention using health promotion principles and their applications. Eventually, this gives an opportunity for the partner to contribute towards eliminating or reducing significantly the risk of LBW.

It is a known fact that the knowledge of the female must be increased since male participation is low [23]. Using the health promotion approach, it has been possible to address the partners not only individually but also by addressing the fathers as a group and as a community intervention. In this community intervention, since the wife has communicated the contents of the discussion with the husband he is already somewhat aware of the intervention when he comes for the discussion. In their day-to-day life, the partners also discuss their concerns regarding the intervention, and then when they meet as a group, the topic becomes a group discussion. Then, this commonly becomes a collective idea. As a result, partners’ knowledge improves and enthusiasm gradually increases. In the intervention, fathers' participation increased, and it became a topic they discussed on a daily basis. This, in turn, consequently increased the partner's partners’ knowledge about the determinants of low birth weight (LBW).

It is well known that when the knowledge is less, such participants are vulnerable and could easily trigger LBW [9, 21,22,23,24]. In an intervention, it is well known that the knowledge of the participants who have somewhat knowledge will further increase the knowledge [6, 10]. This intervention has the potential to address participants with significantly very low knowledge. Also, it has been possible to increase their knowledge significantly in relation to LBW and enhance the potential LBW babies.

In order to increase the knowledge, the methodology used has proven to be a success. A participatory approach using appropriate videos and simple examples is an effective method [25]. Using appropriate videos and simple examples that the community understands, where no lectures were done but discussions were carried out has brought about a change.

Since the study used a participatory approach in the preparation of tools, and also used simple terminologies that are used by the community, it has been successful in increasing the participation, enthusiasm and knowledge of the participants.

The lecture discussions that were commenced upon discussing about the mother’s vision or dream about the child to be born broadened the understanding or the vision of the pregnant mothers on their future expectations and hopes for the baby to be born. Inquired about what they already know about LBW and the determinants of LBW, and addressing the components that they are unaware of, helped them to easily understand and increase the knowledge.

Addressing the importance of the first 1000 days in an individual’s life in determining his/her dream for their child was a good entry point for the discussion. The mothers realized that birth weight is an important parameter which determines the future of the child. After realizing it the mothers became more enthusiastic to acquire knowledge of achieving it.

When mothers realized the importance of good intra uterine growth, they were enthusiastic in learning it. When the need of improving birth weight was a possibility and doing so was seen as achievable, they were interested in understanding the way to achieve it.

Significant improvement of knowledge in both IG and CG was not an unexpected finding, as the existing routine healthcare system takes many measures to improve the knowledge of pregnant mothers as well as their partners. However, the magnitude of knowledge improvement was greater in the IG compared to the CG, both in the total sample as well as among those with low initial scores on knowledge. This fact suggests that adding the intervention model used in this study incorporated with the existing antenatal services can enhance the knowledge gains achieved through existing field antenatal services. This intervention has shown that male participation is important. The community intervention using the health promotion approach has been able to get the partner involved in the intervention. Thus, increasing the knowledge of the partner has played a significant role in reducing births with low weight, not only individually but also as a community.

In this intervention, it is evident that the number of LBW babies being born can be reduced by increasing the knowledge. Further, the study clearly shows that the participants with the lowest knowledge also have significantly improved. Thereby, these participants that have low knowledge, by increasing knowledge, have been able to reduce the number of births with low weight.

4.1 Limitations

Districts that have almost similar socio-demographic and educational backgrounds have been selected to carry out the studies. Assigning interventions and non-interventions to participants in completely different districts, respectively, is a limitation of the study. The intervention and the control were not done in the same district to avoid contaminations, but there may have been other interventions done by other parties or may have had other exposures.

There could have been a lack of uniformity in measuring birth weight due to defects in scales since the birth weight was taken from pregnancy outcome record cards and there is a possibility that the documents can carry some errors in information. The partner’s participation was less for some sessions due to their unavailability. Other studies on community-based health promotion interventions to enhance knowledge in relation to LBW are very low.

5 Conclusions

Implementing and evaluating the community-based health promotion intervention on pregnant mothers and their partners to increase knowledge on birth weight and its determinants was successful. The birth weight was increased after the intervention. By improving the knowledge, the community has taken control over the conditions that govern the determinants of low birthweight and thereby the birthweight has been increased. The total population of pregnant mothers and partners of the IG demonstrated significantly higher knowledge levels in both pre- (p < 0.001) and post- (p < 0.001) intervention assessments. The number of low birth weights has been significantly reduced (p < 0.001).

The mothers took up the task of addressing the determinants by acquiring knowledge on LBW and moved to working out ways of addressing the reached outcomes showing that lay people are quite well equipped to deal with such seemingly sophisticated tasks. This capacity can usefully be engaged in addressing LBW in communities similar to those studied.