Unlike other calculators, the calculator that is contained in this "Mitera" Center app is based on guidance from the most updated medical guidelines. Mitera Center developed this Calculator to help its patients determine their estimate due dates. Accurate dating of pregnancy is important to improve outcomes. Our calculator uses data from the last menstrual period, the first accurate ultrasound examination and the IVF-transfer date to determine gestational age and estimate due date. It is provided as a reference aid. The Calculator should not be used as a medical advice nor as a substitute for the gynecologists professional judgment. We would be happy to give you any further information, anytime you may ask.