A dating scan is an ultrasound examination which is performed in order to establish the gestational age of the pregnancy. Dating scans also reveal other important information such as: the number of fetuses and gestation sacs. the presence of a heart beat.

What is the best method to date a gestation?

Ultrasound is the most reliable method to establish pregnancy dating, particularly first-trimester ultrasound[1].

What is the most accurate sonographic method for dating a pregnancy?

Ultrasound measurement of the embryo or fetus in the first trimester (up to and including 13 6/7 weeks of gestation) is the most accurate method to establish or confirm gestational age.

Do you go by LMP or ultrasound?

Because few women know the exact day they ovulated or conceived, an ultrasound done in the first trimester of pregnancy has been shown to the be the most accurate way to date a pregnancy. If an ultrasound date in the first trimester differs from your LMP date by seven days or more, we would go with the ultrasound.

How old is my preemie?

If your babys chronological age is 20 weeks, but he was born 6 weeks premature, you subtract the number of weeks premature (six) from his chronological age of 20 weeks to get 14 weeks. This is your babys adjusted age. To determine your babys adjusted age in months, just divide by four.