Based on this information, an approximate due date will be determined.
Determining an Estimated Date of Delivery by ultrasound in the first trimester It is possible to become pregnant even though a woman has not had a period for a long period of time.
For example, if there is a gestational age based on the beginning of the last menstrual period of 9.0 weeks, and a first-trimester obstetric ultrasonography gives an estimated gestational age of 10.0 weeks (with a 2 SD variability of ±8% of the estimate thereby giving a variability of ±0.8 weeks), the difference of 1.0 weeks between the tests is larger than the 2 SD variability of the ultrasonography estimate, indicating that the gestational age estimated by ultrasonography should be used as the official gestational age.
In situations such as these, determining a due date based on the first day of your last regular period will not be accurate.
In order to confirm a due date, an ultrasound will be done.
The fertilization age (also called embryonic age and later fetal age) is the time from the fertilization.
It usually occurs within a day of ovulation, which, in turn, occurs on average 14.6 days after the beginning of the preceding menstruation (LMP).