How is the due date calculated for IVF?

Patient's question:

Test tube baby implantation was successful! I'm so happy. I don't know how this due date is estimated? Is it the same as getting pregnant naturally? What kind of help I need: Explanation needed

Doctor's answer:

Medically, it is stipulated that the estimated due date is calculated from the first day of the last menstrual period for naturally conceived pregnancy, with the entire pregnancy lasting 40 weeks. The timing for egg retrieval in IVF is successfully completed 14-15 days after the last menstrual period has started, taking about 2 weeks. Compared to a naturally conceived pregnancy, it should be increased by 2 weeks, so the entire pregnancy duration should be 38 weeks. Unlike the petri dishes used domestically, the embryos transplanted in IVF are typically 5-day blastocysts.