Objective: We aimed to investigate the impacts of the bladder fullness on the parameters of first-trimester uterine artery Doppler. Methods: Fifty-one pregnant women, who admitted to our clinic for the first-trimester aneuploidy screening, participated in this prospective study. Bilateral uterine artery Doppler parameters were first measured when the bladder was full. The second measurement was carried out by the same clinician right after the bladder was emptied. Results: The mean weeks of gestation of the patients were 12.5±0.7. With the full bladder, the mean uterine artery pulsatility index (UtA PI) was 1.80±0.65 on both right and left sides. In the measurements carried out when the bladder was empty, UtA PI was 1.77±0.58 on the left side and 1.71±0.59 on the right side (p=0.512 and p=0.503, respectively). Conclusion: Bladder being full when performing preeclampsia screening during first-trimester aneuploidy screening does not affect the parameters of uterine artery Doppler.