Percentiles of Fetal Birth Weight
Prenatal Testing
Obie Editorial Team
This table shows the percentiles of birthweights in grams by weeks of the pregnancy and gestational age.
Percentiles of Birth Weight (grams) for gestational Age: US 1991 Single Births
Alexander et al Ob-Gyn 1996
| Weeks | 10th%tile | Average | 90th%tile |
| 20 | 275 | 412 | 772 |
| 21 | 314 | 433 | 790 |
| 22 | 376 | 496 | 826 |
| 23 | 440 | 582 | 882 |
| 24 | 498 | 674 | 977 |
| 25 | 558 | 779 | 1138 |
| 26 | 625 | 899 | 1362 |
| 27 | 702 | 1035 | 1635 |
| 28 | 798 | 1196 | 1977 |
| 29 | 925 | 1394 | 2361 |
| 30 | 1085 | 1637 | 2710 |
| 31 | 1278 | 1918 | 2986 |
| 32 | 1495 | 2203 | 3200 |
| 33 | 1725 | 2458 | 3370 |
| 34 | 1950 | 2667 | 3502 |
| 35 | 2159 | 2831 | 3596 |
| 36 | 2354 | 2974 | 3668 |
| 37 | 2541 | 3117 | 3755 |
| 38 | 2714 | 3263 | 3867 |
| 39 | 2852 | 3400 | 3980 |
| 40 | 2929 | 3495 | 4060 |
| 41 | 2948 | 3527 | 4094 |
| 42 | 2935 | 3522 | 4098 |
| 43 |
2907 | 3505 | 4096 |
| 44 | 2885 | 3491 | 4096 |
