Introduction: Pregnancy complicated by diabetes requires increasing health care resources for controlling sugar levels during pregnancy and reduce the severe perinatal consequences. Now a days changing lifestyle patterns have changed susceptibility to disease. This study was conducted to determine and compare some of the lifestyle factors (pregnancy self-care, perceived social support and perceived stress) of women with gestational diabetes and healthy pregnant women. Materials and Methods: A comparative- descriptive study was conducted on 100 pregnant women with definite diagnosis of gestational diabetes (diabetic group) and 100 healthy pregnant women (controls) attending teaching health centers affiliated to the Shahid Beheshti University of Medical Sciences in 2013. Data were collected through interviews using a questionnaire related to pregnancy self-care, perceived social support and perceived stress. Data were analyzed using SPSS-18 software. Results: Demographics and obstetrics variables were similar in the diabetes and the controls groups mean pregnancy self-care score was 71.9 and 81.87, respectively (P<0.001), mean perceived social support the was 65.75 and 73.88, respectively (P<0.001), and mean score of perceived stress was 51.57 and 60.27, respectively (P<0.001). Conclusions: Study results showed that pregnant women with gestational diabetes had less self-care, social support and perceived stress. This study further reveals the importance of women’s self-care and perceived social support during pregnancy. The incidence of gestational diabetes can be prevented through increased awareness and education of pregnant women regarding appropriate lifestyles during pregnancy and any interventions that could improve them.