[Glossary] OB calculations
- GA: Gestational Age.
- Fetal age: Conceptional age.
- EFW: Estimated fetal weight.
- AUA: Arithmetic ultrasound age.
- DOC: Date of conception.
- LMP: Last menstrual period.
- EDD: Estimated due date.
In Early OB
- CRL: Crown-rump length
- GS: Gestational sac.
In Mid-late OB
- AC: Abdominal circumference.
- HC: Head circumference.
- FL: Femur length.
- BPD: Biparietal diameter.
References
- Early OB calculations: Hadlock 1992.
Fetal Crown-Rump Length: Reevaluation of Relation to Menstrual Age with High-Resolution Real-Time US. - Mid-late OB calculations: Hadlock 1984
Hadlock F.P, Deter R.L, Harrist R.B. and Park S.K, Estimating fetal age: computer-assisted analysis of multiple fetal growth parameters, Radiology, 152, pp 497-501, 1984 - EFW equations:
EFW by AC, BPD FL, and HC: Hadlock 1985
Hadlock F.P, Harrist R.B, Sharman R.S, Deter R.L, Park S.K, Estimation of fetal weight with the use of head, body, and femur measurements–a prospective study, Am.J.Obstet.Gynecol., 151, pp 333-337, 1985
Appendix Tables
| CRL （CM） | GA （WEEK） |
|---|---|
| 0.222017 | 5 |
| 0.323257 | 5.5 |
| 0.458221 | 6 |
| 0.633076 | 6.5 |
| 0.853455 | 7 |
| 1.12393 | 7.5 |
| 1.44749 | 8 |
| 1.82517 | 8.5 |
| 2.25575 | 9 |
| 2.73569 | 9.5 |
| 3.25926 | 10 |
| 3.81889 | 10.5 |
| 4.40564 | 11 |
| 5.00986 | 11.5 |
| 5.62178 | 12 |
| 6.23223 | 12.5 |
| 6.83319 | 13 |
| 7.41828 | 13.5 |
| 7.98308 | 14 |
| 8.5254 | 14.5 |
| 9.04534 | 15 |
| 9.54531 | 15.5 |
| 10.03 | 16 |
| 10.5061 | 16.5 |
| 10.9826 | 17 |
| 11.4704 | 17.5 |
| 11.9826 | 18 |
| 12.5346 | 18.5 |
| 13.1446 | 19 |
| 13.8342 | 19.5 |
| GS（CM） | GA（WEEK） |
|---|---|
| 0.2 | 4.985714286 |
| 0.3 | 5.114285714 |
| 0.4 | 5.228571429 |
| 0.5 | 5.357142857 |
| 0.6 | 5.485714286 |
| 0.7 | 5.614285714 |
| 0.8 | 5.742857143 |
| 0.9 | 5.871428571 |
| 1 | 5.985714286 |
| 1.1 | 6.114285714 |
| 1.2 | 6.242857143 |
| 1.3 | 6.371428571 |
| 1.4 | 6.5 |
| 1.5 | 6.614285714 |
| 1.6 | 6.742857143 |
| 1.7 | 6.871428571 |
| 1.8 | 7 |
| 1.9 | 7.128571429 |
| 2 | 7.257142857 |
| 2.1 | 7.371428571 |
| 2.2 | 7.5 |
| 2.3 | 7.628571429 |
| 2.4 | 7.757142857 |
| 2.5 | 7.885714286 |
| 2.6 | 8 |
| 2.7 | 8.128571429 |
| 2.8 | 8.257142857 |
| 2.9 | 8.385714286 |
| 3 | 8.514285714 |
| GA （WEEK） | AC （CM） | HC（CM） | FL（CM） |
|---|---|---|---|
| 12 | 4.58288 | 6.79971 | 0.7244 |
| 12.5 | 5.26562 | 7.52234 | 0.89625 |
| 13 | 5.94338 | 8.2402 | 1.0664 |
| 13.5 | 6.61615 | 8.9531 | 1.23485 |
| 14 | 7.28392 | 9.66083 | 1.4016 |
| 14.5 | 7.9467 | 10.3632 | 1.56665 |
| 15 | 8.6045 | 11.0601 | 1.73 |
| 15.5 | 9.25731 | 11.7512 | 1.89165 |
| 16 | 9.90512 | 12.4363 | 2.0516 |
| 16.5 | 10.5479 | 13.1154 | 2.20985 |
| 17 | 11.1858 | 13.7882 | 2.3664 |
| 17.5 | 11.8186 | 14.4544 | 2.52125 |
| 18 | 12.4465 | 15.114 | 2.6744 |
| 18.5 | 13.0693 | 15.7667 | 2.82585 |
| 19 | 13.6872 | 16.4123 | 2.9756 |
| 19.5 | 14.3001 | 17.0507 | 3.12365 |
| 20 | 14.908 | 17.6816 | 3.27 |
| 20.5 | 15.5109 | 18.3049 | 3.41465 |
| 21 | 16.1088 | 18.9203 | 3.5576 |
| 21.5 | 16.7017 | 19.5277 | 3.69885 |
| 22 | 17.2897 | 20.1269 | 3.8384 |
| 22.5 | 17.8726 | 20.7177 | 3.97625 |
| 23 | 18.4506 | 21.2998 | 4.1124 |
| 23.5 | 19.0235 | 21.8732 | 4.24685 |
| 24 | 19.5915 | 22.4376 | 4.3796 |
| 24.5 | 20.1545 | 22.9929 | 4.51065 |
| 25 | 20.7125 | 23.5388 | 4.64 |
| 25.5 | 21.2655 | 24.0751 | 4.76765 |
| 26 | 21.8135 | 24.6016 | 4.8936 |
| 26.5 | 22.3565 | 25.1183 | 5.01785 |
| 27 | 22.8946 | 25.6248 | 5.1404 |
| 27.5 | 23.4276 | 26.121 | 5.26125 |
| 28 | 23.9557 | 26.6066 | 5.3804 |
| 28.5 | 24.4787 | 27.0816 | 5.49785 |
| 29 | 24.9968 | 27.5457 | 5.6136 |
| 29.5 | 25.5099 | 27.9987 | 5.72765 |
| 30 | 26.018 | 28.4404 | 5.84 |
| 30.5 | 26.5211 | 28.8707 | 5.95065 |
| 31 | 27.0192 | 29.2893 | 6.0596 |
| 31.5 | 27.5123 | 29.696 | 6.16685 |
| 32 | 28.0005 | 30.0907 | 6.2724 |
| 32.5 | 28.4836 | 30.4732 | 6.37625 |
| 33 | 28.9618 | 30.8433 | 6.4784 |
| 33.5 | 29.4349 | 31.2007 | 6.57885 |
| 34 | 29.9031 | 31.5453 | 6.6776 |
| 34.5 | 30.3663 | 31.877 | 6.77465 |
| 35 | 30.8245 | 32.1955 | 6.87 |
| 35.5 | 31.2777 | 32.5005 | 6.96365 |
| 36 | 31.7259 | 32.7921 | 7.0556 |
| 36.5 | 32.1691 | 33.0698 | 7.14585 |
| 37 | 32.6074 | 33.3336 | 7.2344 |
| 37.5 | 33.0406 | 33.5833 | 7.32125 |
| 38 | 33.4689 | 33.8186 | 7.4064 |
| 38.5 | 33.8921 | 34.0394 | 7.48985 |
| 39 | 34.3104 | 34.2455 | 7.5716 |
| 39.5 | 34.7237 | 34.4367 | 7.65165 |
| 40 | 35.132 | 34.6128 | 7.73 |
| GA （WEEK） | BPD（CM） |
|---|---|
| 12.5438 | 1.7 |
| 12.9608 | 1.9 |
| 13.3913 | 2.1 |
| 13.8352 | 2.3 |
| 14.2925 | 2.5 |
| 14.7632 | 2.7 |
| 15.2473 | 2.9 |
| 15.7448 | 3.1 |
| 15.9986 | 3.2 |
| 16.5163 | 3.4 |
| 17.0473 | 3.6 |
| 17.5917 | 3.8 |
| 17.869 | 3.9 |
| 18.4336 | 4.1 |
| 19.0115 | 4.3 |
| 19.6029 | 4.5 |
| 19.9036 | 4.6 |
| 20.5151 | 4.8 |
| 21.14 | 5 |
| 21.4575 | 5.1 |
| 22.1025 | 5.3 |
| 22.7609 | 5.5 |
| 23.0951 | 5.6 |
| 23.7737 | 5.8 |
| 24.118 | 5.9 |
| 24.8166 | 6.1 |
| 25.1709 | 6.2 |
| 25.8897 | 6.4 |
| 26.2541 | 6.5 |
| 26.993 | 6.7 |
| 27.3674 | 6.8 |
| 27.7452 | 6.9 |
| 28.5109 | 7.1 |
| 28.8988 | 7.2 |
| 29.29 | 7.3 |
| 30.0825 | 7.5 |
| 30.4838 | 7.6 |
| 30.8884 | 7.7 |
| 31.2964 | 7.8 |
| 31.7077 | 7.9 |
| 32.5404 | 8.1 |
| 32.9618 | 8.2 |
| 33.3866 | 8.3 |
| 33.8147 | 8.4 |
| 34.2461 | 8.5 |
| 34.6809 | 8.6 |
| 35.119 | 8.7 |
| 35.5605 | 8.8 |
| 36.0054 | 8.9 |
| 36.4536 | 9 |
| 36.9052 | 9.1 |
| 37.3601 | 9.2 |
| 37.8183 | 9.3 |
| 38.2799 | 9.4 |
| 38.7449 | 9.5 |
| 39.2132 | 9.6 |
| 39.6849 | 9.7 |
| 40.1599 | 9.8 |
| 40.6383 | 9.9 |
| 41.12 | 10 |
| 41.6051 | 10.1 |
| 42.0935 | 10.2 |
