Results: In this study, 19 patients fulfilled the inclusion criteria as patients with polyhydramnios who responded to conservative treatment. For these patients, the mean foetal renal artery PI was 2.08 (range 1.5-3.0) at the first sonographic examination, and the mean foetal renal artery PI was 1.94 (range 1.53-2.69) after the conservative treatment. However, there was no statistically significant difference between these two groups