A dating scan is more accurate. If the scan date differs from your last period dates, the scan date will be used. The scan will usually show that your pregnancy is less far along than suggested by your LMP.

Does a 2 week old fetus have a heartbeat?

A fetal heartbeat may first be detected by a vaginal ultrasound as early as 5 1/2 to 6 weeks after gestation. Thats when a fetal pole, the first visible sign of a developing embryo, can sometimes be seen. But between 6 1/2 to 7 weeks after gestation, a heartbeat can be better assessed.