Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Your pregnancy due date is calculated by adding 266 days (38 weeks) to your ovulation and fertilization date or 280 days to the first day of your last menstrual period (LMP). Sometimes scan reports may vary, please repeat scan and consult your gynecologist as she will examine and treat you accordingly. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Penchila Prasad Kandikattu