NOTE
Accuracy of Sonogram Dating
Crown-Rump Length (CRL)+/- 5 days <9 weeks
+/- 7 days 9-14 weeksBPD, HC, AC, FL+/- 7 days 14-16 weeks
+/- 10 days 16-22 weeks
+/- 14 days 22-28 weeks
+/- 21 days 28+ weekshttp://ebookobgyne.net