Sampling and random allocation method
BLIND
The present study was approved by the committee of ethics of Ahvaz Jundishapur University of Medical Sciences (IR.AJUMS.REC.1399.401) and was registered in Iranian Registry of Clinical Trials (IRCT20160427027633N8). First, According to the information of Kermanshah health center, Kermanshah city was divided into 4 geographical regions (or 4 classes) based on socio-economic status of the residents. These four regions included 76 healthcare centers, and from the healthcare centers of each region, one was selected by simple random method (drawing lots). These centers were Taleghani, Hafezieh, Shahid Souri, and Haj Daei, from which 28, 34, 22, and 16 women were selected by convenience sampling method (based on the share of each center). After making the necessary arrangements and obtaining a permit, the researcher went to these centers and selected eligible women. In this way, by referring to the Sib system, information about the women who were covered by the center and met the study entry criteria was extracted and they were contacted by phone to come to the health center to participate in the study. The study aims and method were explained to pregnant women and their husbands in a face-to-face meeting and informed written consent was gained from them (pregnant women and their husbands). The telephone numbers of the women and their husbands were taken, and the researcher gave her telephone number to them, and they were advised to inform the researcher when the mother gave birth to the baby. After the women completed the questionnaires online on the third day after delivery, the educational content was offered to the intervention group. It should be noted that the membership of the husbands in the virtual (Skype) group was monitored by checking whether or not they had installed Skype on their cellphones, and in case they had not, it was installed on their cellphones. Necessary training on how to use Skype was given to them.The women were randomly divided into 6 blocks with an allocation ratio of 1:1 to the intervention and control groups. Blocked randomization was performed by a person who was not involved in data collection, and in order to conceal random allocation, opaque sealed packets in random sequence were used. To this aim, first, a random sequence was created by a table of random numbers and recorded on a card and the cards were placed in packets according to the random sequence. Packets were opened in the order of woman entry in the study and they were allocated into either the intervention or control group. Data analysis was performed by a statistician who was unaware of the nature of the codes. Due to the nature of the intervention, it was not possible to blind neither the participants nor the researchers.