Background: Pregnant women have a high prevalence of vitamin D insufficiency has detrimental effects on fetal and maternal complications. Aim: This study aimed to assess the effectiveness of applying for a social-platform educational program on primigravida women's knowledge regarding vitamin D deficiency during pregnancy. Subjects and method: Design: Quasi-experimental research design (pre and post-test) was utilized. Setting: The study was conducted at the Maternal and Child Health Center at Talkha City and Elsalakawy Maternal and Child Health Center at Mansoura City belonging to Dakhahlia Governorate, Egypt. Subjects: A convenience sample of (300) primigravida women were enrolled. Tool for data collection: Tool: Online-administered questionnaire, it covered four parts personal data, current obstetric history, primigravida women's knowledge about vitamin D deficiency, and women's opinion about a social-platform educational program. Results: There were highly statistically significant differences between primigravida women's knowledge pre-and post-social-platform educational program implementation at p values=< 0.001. The results also, revealed that all of the studied primigravida women reported that the contents were enough and were satisfied with the social-platform educational program. Conclusion: The present study concluded that utilizing social-platform educational program implementation was effective in improving primigravida women's knowledge regarding vitamin D deficiency during pregnancy. Recommendations: The provision of continuing education programs in a different setting is recommended to increase primigravida women's knowledge about the importance of adequate intake of vitamin D to improve pregnancy outcomes.