After all, unless you went the IVF-route, your physician has no way of knowing the exact time of conception. An early ultrasound, usually done at about 6 to 9 weeks, can give the most accurate due date estimation by measuring the size of the embryo or fetus. Radiology ; Please try again. Mine did! Accuracy of gestational age estimation by means of fetal crown—rump length measurement.
Early ultrasound due dates have a margin of error of roughly 1.
When and Why Your Doctor May Change Your Due Date
Accordingly, in creating recommendations and the associated summary table, single-point cutoffs were chosen based on expert review. Commit-tee Opinion No. In December Babies Change in due date after 20w ultrasound? But then again with my first baby I was spot on with dates, he always measured big and he was a week overdue… these babies like to be tricky! As the baby gets bigger, it starts to express its individual growth potential. Jump to Your Week of Pregnancy. If you can't remember your last menstrual period date or if you have consistently irregular cycles, the doctor can use an early ultrasound to give you a fairly reliable due date.