Introduction: Gestational Diabetes Mellitus (GDM) has well recognised adverse health implications for the mother and her newborn that are both short and long term. Obesity is a significant risk factor for developing GDM and the prevalence of obesity is increasing globally. Aim: to evaluate the effectiveness of applying instructional scheme for pregnant women on their knowledge, attitude and clinical implications. Subject and Methods: quasi-expermintal research design with convenience random sampling was used which calculated 60 pregnant women in the first trimester using three tools. Results: The results indicates a statistically significance differences in post and follow-up implementation of instructional scheme phase comparing to pre instructional scheme phase in total knowledge, attitude, and clinical implications. Conclusion & Recommendations: there are a remarkable increase and improvement of the pregnant women 's level of knowledge and acquiring the ultimate positive and noticeable improvement in the attitude and their clinical implications ,and there are obvious needs for instructional scheme offered on simple media to pregnant women to prevent occurrence of gestational diabetes mellitus. Within this context, there is a great demand for strategies and programs that take into consideration all the social, financial, and psychological contexts.