The aim of this study was to investigate the intra- and interobserver reproducibility of three-dimensional (3-D) power Doppler (3-DPD) data acquisition from women at 12 weeks gestation, which were then subsequently measured by a single observer. Women with an uncomplicated, viable singleton pregnancy were scanned between 12 + 0 and 13 + 6 weeks gestations with a Voluson 730 Expert. 3-DPD data were acquired of the whole placenta by two observers: the first observer captured two datasets and the second a single dataset. Each dataset was analysed using VOCAL in the A plane with 9 degree rotation steps. Eighteen low risk women were recruited with a total of 54 datasets analysed. The intraclass correlation coefficient (ICC) was highest for the vascular indices vascularisation index (VI) and vascularisation-flow index (VFI), greater than 0.75. ICC for flow index (FI) showed moderate correlation at 0.47 to 0.65. Bland Altman plots showed the most precise vascular index to be the FI (-15% to 10% for interobserver agreement). There was no bias between datasets. Prospective studies are now required to identify if this analysis tool and method is sensitive enough to recognise patients with early-onset placental dysfunction.