Want to know what date and day of the week you were likely conceived on?
Determining the Estimated Due Date The estimated due date (EDD or EDC) is the date that spontaneous onset of labor is expected to occur. Conceptional age, menstrual age, and ultrasound age: a second-trimester comparison of pregnancies of known conception date with pregnancies dated from the last menstrual period.
The due date may be estimated by adding 280 days ( 9 months and 7 days) to the first day of the last menstrual period (LMP). The accuracy of the EDD derived by this method depends on accurate recall by the mother, assumes regular 28 day cycles, and that ovulation and conception occurs on day 14 of the cycle.
Use of the LMP to establish the due date may overestimate the duration of the pregnancy, and can be subject to an error of more than 2 weeks [5-7].
In cases where the date of conception is known precisely, such as with in vitro fertilization, the EDD is calculated by adding 266 days to the date of conception. American College of Obstetricians and Gynecologists.
However, ultrasound determination of the date of ovulation has the same imprecision as does the ultrasound estimate of the gestational age and, therefore, a precise date of conception cannot usually be determined as with in vitro fertilization.
In addition, although a woman is most likely to become pregnant if she has sex on the day of ovulation conception may also occur from live sperm still in her reproductive tract on the day of ovulation if she had sex for up to five days before ovulation [26,27].
Your due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (assuming a 28 day cycle).
Note that your menstrual period and ovulation are counted as the first two weeks of pregnancy.
More in-depth explanations can be found in the glossary of terms located beneath the calculator.