Abstract Study question Short term outcomes of oocyte donation (OD) pregnancies are known. Yet, long term effect of OD pregnancies on mother’s health are lacking. Summary answer Comparing women after OD pregnancies to spontaneous pregnancies or nulliparous women, a higher risk of thyroid diseases was found (1.41, p < 0.0001 and 2.13, p < 0.0001, respectively) What is known already Short term outcomes of oocyte donation pregnancies show increased risk of placental disease and pregnancy-related hypertensive disorders. Study design, size, duration This retrospective cohort study, conducted from 2000 to 2018, utilized the computerized records of a major healthcare provider. It compared the demographic data and long-term health outcomes of mothers who had undergone OD pregnancies with three groups: In Vitro Fertilization using autologous oocytes, spontaneously pregnancies, and nulliparous women. Participants/materials, setting, methods The study tracked the onset of chronic diseases from the date of delivery to the diagnosis of any chronic disease. The risk of various diseases and mortality among these groups was assessed using a Cox proportional hazards model. This model adjusted for variables such as age at the index date, number of children, body mass index (BMI), and smoking habits. Statistical significance was determined using two-sided p-values, with a threshold of P < 0.05. Main results and the role of chance Regarding long-term outcomes, no difference was found between mothers after oocyte donation comparted to mothers after IVF (See table 1).. When comparing oocyte donation pregnancies to mothers after spontaneous conception, mothers after oocyte donation had less lower prevalence of rheumatology diseases (6% vs 8.9%) and more higher prevalence of thyroid diseases (21.9% vs. 17.6%). However, in cox regression, taking into account smoking, number of birth and mom’s age, we only found a higher risk of thyroid diseases (OD 1.41, p < 0.0001). Lastly, oocyte donation pregnancies compared to nulliparous had more thyroid diseases (21.9% vs. 6.7%, p < 0.001), also in cox regression (OD 2.13, p < 0.0001) Limitations, reasons for caution The temporal aspect of chronic disease diagnosis; a diagnosis made at a specific point does not preclude the presence of the disease at an earlier time. Also, the infrequency of some conditions within our study population could have reduced the statistical power to detect differences or associations. Wider implications of the findings The longer-term health outcome for women conceiving after OD is reassuring, and is very similar to that of IVF children and naturally conceived children, exempt for higher risk of thyroid disease. The main recommendation should be a yearly surveillance of thyroid function. Trial registration number 0046-18-BBL