['To investigate Doppler flow patterns of renal interlobar veins (RIV) in left (L) and right (R) kidney in relation to gestational age and to intrarenal pyelocalyceal diameters (PCD).', 'Cross-sectional study involving 6 groups of women: (1) non-pregnant women, women pregnant between weeks (2) 11-14, (3) 18-23, (4) 28-33, (5) 37-40 and (6) women <5 days post delivery. During standardized renal duplex ultrasound scan, PCD (mm) was measured and venous impedance index (VI = [peak flow (PV) - presystolic flow]/PV) of RIV was defined. Comparison between L and R kidney was performed by repeated-measures analysis of variance for VI and by t tests for PCD.', 'A total of 150 women were examined, 25 in each group. In the early third trimester of pregnancy, L VI was significantly higher than R VI (0.38 +/- 0.01 vs. 0.33 +/- 0.01, p < 0.0001) and L PCD was significantly lower than R PCD (3.90 +/- 3.68 vs. 6.25 +/- 4.03, p = 0.03).'] Is interlobar venous flow different between left and right kidney in uncomplicated third trimester pregnancy?