The Estimated Date of Confinement (EDC), also known as expected date of delivery/estimated due date (EDD) or simply due date, is a term describing the estimated delivery date for a pregnant woman. Normal pregnancies last between 37 and 42 weeks.
It is a calculated date (i.e., an estimation), determined by counting forward 280 days (40 weeks) from the first day of the woman's last menstrual period.
The EDC can be confirmed with a transvaginal or transabdominal sonography (ultrasound) of the fetus. The earlier the sonography is done in gestation, the more reliable the confirmation of the date. The EDC can be changed if sonography and the last menstrual period are not in agreement.
Origins of the term
Confinement is a traditional term referring to the period of pregnancy whereby a woman would be confined to bed (in an effort to reduce risk of premature delivery). Except in threatened pregnancies (for example, in pre-eclampsia), this is no longer a part of antenatal care.