Serial scans need to be continued right up to delivery to be able to detect late onset fetal growth restriction.
EFWs at term are at least as accurate as at pre-term gestations, with 72.8% vs. 69.6% falling within +/-10% error. See Table, from reference 26.
| <37 weeks (N=671) | 69.6% (65.9-72.8) | 85.6% (83.3-88.5) | 91.9% (90.0-94.0) |
| ≥ 37 weeks (N=1625) | 72.8% (70.8-75.1) | 89.6% (88.2-91.2) | 95.9% (94.9-96.8) |
If fetal head measurements are difficult due to engagement, alternate formulae (e.g.Hadlock AC, FL) can be used to estimate fetal weight
26. Francis A, Tonks A, Gardosi J (2011) Accuracy of ultrasound estimation of fetal weight at term Arch Dis Child Fetal Neonatal Ed;96:Fa61 http://dx.doi.org/10.1136/adc.2011.300161.24