Study Design and Participants
This cross-sectional study was conducted during the COVID-19 pandemic in Sistan-baluchestan province, Iran, between August 16- September 30, 2020. Inclusion criteria included the Iranian nationality, Zahedan, Khash, Mirjaveh, and Saravan residency, singleton pregnancy, ability to read and write in Persian, age range of 18-40 years, pregnancy over 10 weeks, no experience of severe psychological crises over the past six months (declared by the participants), no known medical disorders or problems, and obstetrics-related risk factors during and before pregnancy based on medical files approved by the physician or midwife at the center and not having COVID-19 disease. The exclusion criteria were lack of willingness to participate in the study and incomplete questionnaires.
Sample size and sampling method
To obtain the research objectives, the maximum sample size was calculated as the sample size based on the first objective of the research. Therefore, the sample size for the self-care scale was calculated at 40 cases based on the study conducted by Momeni Javid et al.  with an acceptable error of 0.05 around the mean (m=71.9), 95% confidence interval, 90% statistical power, and standard deviation of 11.48. Moreover, based on the study conducted by Li et al., the sample size for the scale of knowledge was calculated at 50 cases with an acceptable error of 0.05, 95% confidence interval, 90% statistical power around the mean (m= 3.56) and standard deviation of 0.61, 25 subjects for the scale of perceived severity around the mean (m=4.09) and the standard deviation of 0.51, and 78 cases for the scale of perceived behavioral control around that mean (m=3.25) and the standard deviation of 0.72. Furthermore, the sample size for the scale of health anxiety was calculated at 267 cases considering the rate of health anxiety (50.7%) and frequency (12%) reported in the study conducted by Corbet . Finally, in the present study, the sample size was estimated at 400 subjects based on the maximum sample size obtained from the level of health anxiety and considering the design effect of 1.5. Finally, considering 10% sample attrition, 440 subjects were entered into the study.
Sampling was conducted in the healthcare centers. Most of the pregnant women have health records in these healthcare centers and posts. For sampling, a two-stage cluster sampling was carried out. So that, each of the cities covered by the University of Medical Sciences were divided into four clusters: north, south, east and west. Then, from each cluster, according to the number of pregnant women, relative coverage is given to each city. One or two centers were randomly selected using a randomizer software (www.random.org). 8 centers from Zahedan, 4 centers from Khash, 3 centers from Saravan and one center from Mirjaveh were randomly selected. Then, a list of all pregnant women at each center was extracted from the health records and the samples was randomly selected from the ordered numbers. Afterward, Using the phone number registered in each record, the researcher called the potential participants and invited them to participate in the study and if needed the researcher visited their home. The eligible participants were provided with full explanations about the study objectives and procedures. Also, informed consent obtained before collecting information, and emphasized the importance of honest answers to the questionnaire, and asked them to complete the anonymous questionnaires in a private room. A number of participants were likely to be illiterate, so the questionnaires were completed by the researcher in order for the data collection method to be the same for all individuals. Sampling was continued until the total sample size was reached.
Scales and data collection
Quantitative data was collected using 5 questioners, including:
- Sociodemographic and Obstetrics Characteristics Form:
consisted of questions about the women’s and husband’s ages, the women and husband’s education, the women and husband’s Employment status, number of pregnancies, number of deliveries, gestational age.
- Knowledge of COVID-19 Questionnaire
This 12-item questionnaire assesses people's knowledge of COVID-19. The responses are rated on a 3-point Likert scale, 2=yes, 1=I have no idea, and 0=no, with higher scores signifying a higher level of knowledge.
- Perceived Severity of Covid-19 Questionnaire
The perceived severity questionnaire consists of 5 items is rated on a 5-point Likert scale (strongly agree= 5, ... strongly disagree= 1), with higher scores indicating higher perceived severity.
- Perceived Behavioral Control of Covid-19 Questionnaire
This 11-item questionnaire was rated on a 5-point Likert scale (strongly agree= 5, agree = 4, don't know=3, disagree = 2 and strongly disagree = 1). Higher scores were suggestive of a higher perceived behavioral control.
- Anxiety Health questionnaire
This 18-item standard questionnaire was scored based on a 4-point Likert scale (not at all = 0, sometimes = 1, often = 2, and always = 3), with higher scores signifying higher physical anxiety. This questionnaire was evaluated by Salkowski and Warwick (2002), and its Cronbach's alpha coefficient was reported as 0.71-0.92.
- Pregnancy Self-Care questionnaire
This questionnaire was designed by Momeni-javid in Iran . It consists of 13 questions that are rated on a 4-degree Likert scale (never = 1, sometimes =2, most of the time =3, and always = 4). The minimum and maximum scores are 1 to 52.
The three questionnaires of COVID-19 knowledge, perceived severity, and perceived behavioral control were designed based on the study conducted by Zang et al. . To confirm the content validity of these questionnaires, they were provided to five experts in the field of midwifery and health education, and the necessary modifications were made.
Reliability of the questionnaire was determined by using test–retest method after conducting a pilot study on 20 pregnant women. Both of the reproducibility (ICC = Intraclass Correlation Coefficient) and internal consistency (Cronbach's alpha coefficient) were determined for all questionnaires. ICC (confidence interval) and Cronbach's alpha coefficient for knowledge, perceived severity and perceived behavioral control of COVID-19 were 0.97 (0.94–0.98) and 0.8, 0.91 (0.89-0.93) and 0.86, 0.87 (0.85-0.9) and 0.91, respectively. ICC (confidence interval) and Cronbach's alpha coefficient for Anxiety Health and Pregnancy Self-Care were 0.98 (0.97–0.99) and 0.95, 0.93 (0.91–0.95) and 0.79.
SPSS-22 software is used to analyze the quantitative data. Scoring of sociodemographic, knowledge, perceived severity and perceived behavioral control of covid-19, Anxiety Health and Pregnancy Self-Care questionnaires were described by frequency (percent), as well as mean (Standard Deviation) if the data are normally distributed. The association between Variables were determined using the independent test, ANOVA and Pearson correlation tests in the bivariate analysis. Then, independent variables, with P ≤ 0.05 on bivariate tests inserted into the multivariate linear regression model (enter method). The normality of quantitative data was measured based on Kolmogorov–Smirnov test, all of which were normal. All tests were 2-sided.