Objective To determine for the first time the prevalence of iron deficiency (ID) in Austrian pregnant population. Design Prospective cross-sectional multicentre study. Setting Six hospitals in Austria Population A cohort of 425 pregnant women Methods Patients were classified into four groups of different weeks of gestation. Group 1 was monitored longitudinally, while groups 2 to 4, iron status was sampled only once. Main Outcome Measures Evaluation of the prevalence of ID by comparing the diagnostic criteria of the WHO to the cut-off proposed by Achebe MM and Gafter-Gvili A (Achebe) and the Austrian Nutrition Report (ANR). Results In comparison with the ANR, the prevalence of ID was lower in group 1 and higher in group 2-4 (17.2 % vs 12.17 %, 25.84%, 35.29 % and 41.76 %, respectively) (p-values < 0.01 except group 1). Using WHO’s definition, the prevalence in group 1 was 12,17 % at inclusion, 2 months later 31.7% and further 2 month later 65,71 %, respectively. Using the Achebe definition number of cases doubled (for group 1 the number of cases rose from 13 to 42 (115 patients total); for groups 2 through 4 we observed an increase from 112 to 230 (340 patients total). Conclusions This study showed a prevalence of around 12 % at the beginning of pregnancy, which increased during pregnancy up to 65 %. ID can have a massive impact on the quality of life, so that screening would be entirely justified, as iron deficiency would be easy to diagnose and treat.