Dating a pregnancy from the conception date
This is the time from ovulation to the next menstrual period.
If you have more ultrasounds, each ultrasound report will contain a new due date based on the most recent measurements.An ultrasound allows your doctor to measure the crown-rump length (CRL), or length of the fetus from one end to the other.During the first trimester, this measurement provides the most accurate estimation for the age of the baby.The cookies contain no personally identifiable information and have no effect once you leave the Medscape site. al., Fetal crown-rump length: reevaluation of relation to menstrual age (5-18 weeks) with high-resolution real-time US.
When a doctor performs an ultrasound, they write a report on the findings and include two estimated due dates.