en <span style=font-size:10pt><span style=unicode-bidi:embed><span new= roman= style=font-family: times=><b><span cambria= style=font-family:>Aims:</span></b><span cambria= style=font-family:> Although physical activity has many health benefits during pregnancy, few women engage in regular physical activity. The purpose of this study was to test the validity and reliability of a physical activity scale in pregnant women based on social cognitive theory.</span></span></span></span><br> <span style=font-size:10pt><span style=unicode-bidi:embed><span new= roman= style=font-family: times=><b><span cambria= style=font-family:>Instrument & Methods:</span></b><span cambria= style=font-family:> A multi-phase scale development method was used to build the scale. To generate a pre-final version of the instrument, face and content validity were measured at the following step. The validation of the instrument was evaluated through a sample of 240 pregnant women. Then, the construct validity, internal consistency, test-retest reliability, and Cronbach’s alpha of the scale were calculated<b>.</b></span></span></span></span><br> <span style=font-size:10pt><span style=unicode-bidi:embed><span new= roman= style=font-family: times=><b><span cambria= style=font-family:>Findings</span></b><span cambria= style=font-family:>: In the beginning, a 36-item scale was created by undertaking a qualitative phase. This number was lowered to 24 items after content validity. Seven factors emerged from the exploratory factor analysis (outcome expectations, outcome value, self-efficacy, social support, self-regulation, mutual determinant, and behavior) which accounted for 52% of the observed variance. The confirmatory factor analysis revealed a model with a suitable fitness for the data. For the subscales, Cronbach's alpha coefficients ranged from 0.83 to 0.94, and the Intraclass correlation coefficient ranged from 0.80 to 0.88, which is within acceptable limits.</span></span></span></span><br> <span style=font-size:10pt><span style=unicode-bidi:embed><span new= roman= style=font-family: times=><b><span cambria= style=font-family:>Conclusion:</span></b><span cambria= style=font-family:> The findings showed that the</span> <span cambria= style=font-family:>psychometric properties of the physical activity scale is valid and reliable scale that can help us better understand aspects associated to physical activity in pregnant women. As a result, it has the potential to be employed in the future research.</span></span></span></span> Physical activity,Scale Development,Psychometrics,Pregnant women 467 475 http://hehp.daneshafarand.org/browse.php?a_code=A-10-69776-1&slc_lang=en&sid=4 Z. Arefi 1003194753284600287205 0000000306653072 No Department of Health Promotion and Education, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran R. Sadeghi 1003194753284600287206 0000000319635092 Yes Department of Health Promotion and Education, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran D. Shojaeizadeh 1003194753284600287207 1003194753284600287207 No Department of Health Promotion and Education, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran M. Yaseri 1003194753284600287208 1003194753284600287208 No Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Sh. Shahbazi Sighaldeh 1003194753284600287209 1003194753284600287209 No Department of Reproductive Health, School of Nursing and Midwifery, Tehran University of Medical Sciences, Tehran, Iran