ackground:Nutrition during pregnancy is an important element for the pregnant women and their developing fetus, they must take enough calories andnutrients to provide the essential requirements for both themselves and their fetus and to prevent complications of abnormal weight gain inpregnancy.Objectives:To determine the effect of the nutritional health education program on changing knowledge, attitude, and practice towards a healthy lifestyle duringpregnancy, obtaining optimal weight gain and consequently its effect on maternal and fetal outcomes.Subjects and Methods:An interventional study (pre-post test), in Zagazig university antenatal care outpatient clinic was conducted.Subjects' Criteria:135 pregnant females in the first trimester aged 18-35 years who did not have any chronic medical disorder with Body Mass Index between 18.5and 24.9 kg/m2 were enrolled.Methods:Data collection was done using a semi-structured questionnaire about females’ socio-demographic characteristics, obstetric, family and clinicalhistory. Health education sessions were applied to the pregnant females and their knowledge, attitude, and practice about healthy nutrition wereassessed before and after the intervention. Ultrasound was performed, maternal and fetal outcomes were detected.Results:This study was conducted on 135 pregnant females from whom 9 cases had excluded at the time of delivery due to the detection of ultrasoundabnormalities and 16 women were dropped out during the follow-up period. After the nutritional education program, the proportions of adequateknowledge, attitude, and practice were increased from (28.2% to 77.3%), (8.2% to 75.5%) and (32.7% to 77.3%) respectively (p-value <0.001).There was a statistically significant higher cesarean section, Intra and post-partum complications (85.7%vs 42.9%p<0.001), (71.4% vs17.2%p<0.001) and (25.7%vs7.1% p=0.008) [Odds (95% C.I); 8 (6.7-11.3), 12.1(11.7-13.9) and 4.5(1.2-8.7)], higher neonatal weight and neonatal bloodglucose (p<0.001& 0.009) in over-weight versus optimal weight gain groups respectively. Conclusion :The intervention was effective in increasing pregnant females’ knowledge, attitude, and practice towards healthy nutrition during pregnancy, obtaining optimal weight gain and improving maternal and fetal outcomes