Foetal biometry in polyhydramnios: Does femur length fall behind?

We aimed to identify the growth patterns in polyhydramnios, and therefore evaluated 108 singleton pregnancies complicated with polyhydramnios according to the changes in biparietal diameter (BPD), abdominal circumference (AC) and femur length (FL) percentiles. The pregnancy outcomes according to the growth features were analysed. In the study population, BPD and AC percentiles exhibited a significant increase (p = 0.023 and 0.05, respectively), although FL percentiles showed a significant decrease (p = 0.006) according to the changes in third trimester relative to second trimester. In the overgrown group (n = 52), the FL/BPD ratio was lower (p < 0.001), with more foetuses with FL/BPD ratios below 71 (p = 0.05). In conclusion, there was a significant increase in BPD and AC percentiles and a decrease in FL percentiles in third trimester relative to second trimester in foetuses with polyhydramnios. However, we observed a shorter FL and a lower FL/BPD ratio without associated skeletal dysplasia in overgrown foetuses.