The present randomized field trial was carried out in Izeh (southwest of Iran) From November 2017 to February 2018. A total of 104 participants pregnant women reffered to Physiologic Birth and Counseling Center for antenatal training classes were selected for the study. The participants were randomly assigned to intervention (receive either gain- or loss-framed text messages) and control (did not receive any messages) groups .
The inclusion criteria in this study were being able to read and write, access to cell phones, willingness to participate in the study, not having high risk pregnancy as diagnosed by their midviwes, not having an underlying disease (cardiovascular disease, autoimmune disease, cancer, diabetes, etc.), gestational age of 16 to 28 weeks, as well as age ranges between 18 and 35 years. The women were selected using non-probabilty convenience sampling method.
Two cell phone numbers were taken from pregnant women for the delivey of messages and follow- up. Since "prospect theory" is a much more wide field than Goal framing, the study is focused much on " Goal framing for designing the messages. The desired intervention was composed of 30 identical messages in terms of concept, but different considering the frame which was associated with advantages and disadvantages of not using toothbrushes, dental flosses, and mouthwashes; developed by examining and referring to texts and using message design principles. Then, the given intervention was sent in the form of SMS as a message per day to the individuals in gain- and loss-framed intervention groups, but the control group did not receive any messages. For example, the gain-framed intervention group recieved the message of “If you floss every day, you will have a beautiful smile” while the following message was sent to the loss-framed intervention group; “If you do not floss every day, you may be embarrassed with your smile" . Validity and reliability of messages was confirmed using validity checklist of messages, The pregnant women were also asked to ensure researchers of receiving the messages through replying by a blank message sent to them. If the researcher did not receive a message from pregnant women after 3 days , they would call them or sent them educational messgaes through other cell phone numbers. Eight weeks after sending the messages, the post-test questionnaire was completed by the three study groups in person.
Demographic data sheet
The first part of the questionnaire included demographic characteristics as well as previous pregnancy history which was comprised of 14 items (maternal age, husband’s age, duration of marriage, gestational age, maternal occupation, husband’s occupation, coverage of healthcare insurance services, maternal level of education, husband’s level of education, previous pregnancy history, maternal ethnicity, monthly houshold income, family size, and place of residence).
The second part of the questionnaire consisted of the constructs of knowledge about general health and oral health and hygiene during pregnancy, attitude, behavioral intention, self-efficacy, and practice in mothers concerning oral health. The construct of knowledge with 14 items had been developed about the prevention of oral problems (additional file 1) and was scored as follows; a correct answer was rated 1 and an incorrect answer was assigned with 0. The construct of attitude consisted of 10 items, the behavioral intention contains 6 items, and self-efficacy was comprised of 9 items that had been desigend based on a 5-point Likert-type scale. In terms of scoring, positive items were rated 1, 2, 3, 4, and 5 for totally disagree, disagree, neutral, agree, and totally agree; respectively. This scoring was also done in reverse for negative items which had been used in the construct of attitude. The final part of the questionnaire contained 14 items relating to women’s practice in terms of oral care which were given a score of 1 based on correct and incorrect answers. Items about how to brush and floss the teeth were further completed through direct observation of preganat women’s performace on a mouth and teeth model (examining cases such as correct movement angle or angular 45° of the toothbrush for different parts of the tooth, use of vibrating movements on gum lines, horizontal movement in the occlusal surface, vertical movement of the brush on the anterior and internal surface of the tooth, break-off of suitable floss size, correct winding of the floss around fingers, correct movement of the floss between the teeth and gum line, etc.). Other functions performed by such pregnant women were also recorded in the from of self-reprots.
Validity and reliability
In order to determine the scientific validity of the method, content validity and face validity were employed. Therefore, the opinions of 10 professors in this field were elicited. After summarizing expert opinions, content validity ratio and content validity index were calculated. Using the cut-off point in Lawshe’s table, comparisons showed that the obtained number was greater than that specified in the table (0.99) . After summarizing expert opinions, content validity ratio and content validity index were calculated. The content validity index was found to be perfect (CVI= 1). To measure its face validity, the questionnaire was submitted to 10 pregnant women with conditions similar to those of the target group to have their impression of the importance of the questionnaire items via a 5-point Likert-type scale including absolutely important, important, moderately important, slightly improtant, and absolutely not important. The face validity of the questionnire was approved (impact score 4.5).
The reliability of the questionnaire was also confirmed. The scientific reliability of this research instrument was determined by the researcher using test-retest method. To this end; in a pilot study, the questionnare was given to 10 pregnant women meeting the inclusion criteria within a 14-day interval and it was recompleted by them after two weeks. The Pearson correlation coefficients for the constructs of attitude, behavioral intention, self-efficacy, and practice were by 0.89, 0.89, 0.91, 1; respectively. For the knowledge alpha Cronbach’s was used to assess internal consistency, the result found to be satisfactory, 0.80.
Oral health examinations
The examination of the pregnant women’s teeth was also fulfilled by a dentist and according to the required standards and then the percentage of dental plaque was measured using a dental plaque index (i.e: NPI) [17, 33]. The given index was a valid tool which had been utilized by different researchers. The measurements were performed using disclosing tablets along with plaque measurement chart. In order to calculate the accuracy of the measurment through the dental plaque index by the dentist, the dental plaque was measured shortly after the main measurement for 10 participants in the study. Internal consistency was also performed and approved using Cronbach’s alpha coefficient (0.9).
To determine the sample, the formula for comparing the means was used in which α=0.01 and β=0.1 and x1=0.07(Gain frame Flossing means changes in baseline and week 24) , x2=0.09(Control Flossing means changes in baseline and week 24), s1=0.147(of the week 24), s2=0.123(of the week 24), based on the results of similar previous studies* .
The sample size was considered to be three groups of 36, and a total number of 108 individuals were estimated.
Participants divided into three groups; gain-framed intervention group, loss-framed intervention group, and control group using block randomization technique via 6 blocks. The block size was 6 . Block randomization applied in this study is a commonly used technique in clinical trial design to reduce bias and achieve balance in the allocation of participants to intervention/treatment arms, especially when the sample size is small. This method increases the probability that each arm will contain an equal number of individuals by sequencing participant assignments by block. This approach was done with WinPepi11.0 software. This software generates random groups. In each block, 3 subjects were from the control group and 2 subjects were assigned to gain-group, 2 snumbers to loss-fram and 2 numbers to the control group, which all numbers were arranged randomly. Finally, 16 blocks were used. The steps of using the software listed were as follows: Aetcetera, Randomization (Random allocation)Balanced Randomization, Successive blocks.
The validity of the messages was approved through a message validity checklist. In order to ensure no information bias, the study design was selected as a double-blind type in such a way that the participants were kept unaware of the type of the received messages (gain- and loss-framed ones), and also the assessor of the dental plaque (the dentist) was kept uninformed of the allocation of the given individuals into the groups. Two reseach assistants helped with random allocation, and assigned participants to study gropus.
Results were analyzed in SPSS 23.0 using dependent t-test and Chi-square analysis. The Kolmogorov Smirnov test was employed to determine the normality of data distribution. Analysis of variance (ANOVA) or its non-parametric equivalent was also utilized to compare quantitative values between the three groups. The relationship between qualitative variables was similarly measured through test. To compare attitude, behavioral intention, self-efficacy, and practice of the two intervention groups, the analysis of variance (ANOVA) was used considering the initial values. The significance level was considered at 0.05. G power was used to estimate the power of the study.
All participants were informed about the study and confidentiality protocols. Informed consent was obtained from participants. The Ethics Committee of Ahvaz Jundishapur University of Medical Sciences confirmed the morality and ethics of that study (IR.REFERENCE.REC.1396.554).