What is the EDD calculation based on IVF?

The estimated due date (EDD) calculation based on in vitro fertilization (IVF) is typically determined by counting 266 days from the conception date. During IVF, conception occurs at the time of embryo transfer, and this date is used as a reference point for gestational age calculation.

In traditional obstetrics, the calculated due date is usually derived from the last menstrual period (LMP) and follows a 280-day gestation period. However, for patients undergoing IVF, the conception date is well-defined, which makes calculating the EDD based on 266 days post-conception more precise for this population.

This method is grounded in the understanding that a full-term pregnancy lasts approximately 40 weeks (or 280 days) from the first day of the last menstrual period, but since IVF skips the luteal phase and fertilization occurs shortly after egg retrieval and embryo transfer, 266 days is the appropriate gestational measurement.