Accuracy of Pregnancy Dating by Ultrasonography According to Gestational Age
| Gestational Age (wk) | Ultrasonographic Measurements | Accuracy |
|---|
| <8 6/7 | CRL | ±5 d | | 9–13 6/7 | CRL | ±7 d | | 14–15 6/7 | BPD, HC, FL, AC | ±7 d | | 16–21 6/7 | BPD, HC, FL, AC | ±10 d | | 22–27 6/7 | BPD, HC, FL, AC | ±14 d | | >28 | BPD, HC, FL, AC | ±21 d |
|
Abbreviations: AC, abdominal circumference; BPD, biparietal diameter; CRL, crown-rump length; FL, femur length; HC, head circumference.
aAdapted with permission from American College of Obstetricians and Gynecologists Committee on Obstetric Practice. ACOG Committee Opinion No. 700: methods for estimating the due date. Obstet Gynecol. 2017;129(5):e150-e154. (Reaffirmed 2019). Copyright © 2017 by The American College of Obstetricians and Gynecologists.