Abstract Lactation–pregnancy overlap is defined as the continuation of breastfeeding into the first, second, or even third trimester of pregnancy. Pregnancy during breastfeeding is common in Egypt and is often unintended. Overlap is probably common because many women may not realize they are pregnant for several months after conception. The aim of the present study is to evaluate the effect of an educational program on the outcome of pregnancy during breastfeeding at Assiut City .Designs a quasi-experimental, prospective- cohort study was used. Setting: the study was conducted in a six Maternal and Child Health Centers in West and East Assiut city. Subjects: All lactation women who attended the selected antenatal care centers during the period of data collection were evaluated for eligibility (n=240). The tools: used for data collection consisted of structured interviewing questionnaire (pre-posttest) and follow-up to collect personal, obstetric data, knowledge about balanced meal and calcium intake during pregnancy, consumption of milk products, times/ week symptoms of low calcium intake and information about the effect of breastfeeding– pregnancy overlaps on pregnancy outcome on labor and newborn and Information about the effect of breastfeeding–pregnancy overlaps on pregnancy outcome. Results showed that the majority of the pregnancies were unintended for both groups. Also, statistical significant decrease among the study group than that of the control groups regarding complications as miscarriage, vaginal bleeding during pregnancy, placental separation, delayed fetal growth, elevation of blood sugar, eclampsia and anemia. Likewise, complication of delivery, and indication for cesarean section, were better among the study group than that of the control group. Also, more than one third of newborns' of the study group of mothers were referred to Premature Care Unit compared to nearly half of the control group. Conclusion: pregnant lactating women who attended the educational program had better pregnancy/ delivery outcomes, also, their newborns. Recommendation: Continuous postnatal counseling and health education classes about nutritional needs focusing on pregnancy to prevent complication for mother and children during breast feeding and weaning practices.