Background: Climate change is the greatest threat to public health in the twenty-first century which puts pregnant mothers and their developing fetus at serious risk. Pregnant women's health may be improved by educating them about the hazards involved in their pregnancy. Aim: was to investigate the effectiveness of tailored educational program on knowledge and health-related behaviors toward climate changes and heat stress among pregnant women working outdoors. Design: A quasi-experimental research design. Setting: This research was conducted at obstetrics and gynecological outpatient clinic at Benha University Hospital in Qaliobya governorate, Egypt. Sample: A purposive sample of 108 pregnant women, control group (n=54) and study group (n=54) Tools: Four tools were used for data collection; A structured self-administered questionnaire, Maternal knowledge assessment sheet, Maternal health-related behaviors questionnaire, Adverse pregnancy outcomes questionnaire. Results: showed that there was a highly statistically significant difference between study and control groups regarding their knowledge and health-related behaviors about climate changes and heat stress after implementation of the tailored educational program. Additionally, there was a statistically significant difference between study and control groups regarding adverse pregnancy outcomes. Conclusion: Tailored educational program had a positive effect on the improvement of pregnant women's knowledge and health-related behaviors about climate changes and heat stress. Furthermore, there was a statistical significant reduction in the adverse pregnancy outcomes between study and control groups after applying tailored educational program. Recommendations: Establishing and maintaining effective antenatal care in the face of harsh life circumstances through new educational interventions to lessen the detrimental effects on maternal and fetal health which brought on by the climate changes conditions.