The aim of the study was to determine, for the first time, in a prospective cross-sectional multicenter study, the prevalence of iron deficiency (ID) in an Austrian pregnant population. A cohort of 425 pregnant women was classified into four groups of different weeks of gestation. Group 1 was monitored longitudinally, while groups 2-4, iron status, were sampled only once. Evaluation of the prevalence of ID was performed by comparing the diagnostic criteria of the WHO to the cutoff proposed by Achebe MM and Gafter-Gvili A (Achebe) and the Austrian Nutrition Report (ANR). In comparison with the ANR, the prevalence of ID was lower in group 1 and higher in groups 2-4 (17.2% vs. 12.17%, 25.84%, 35.29%, and 41.76%, respectively) (p-values < .01 except group 1). According to WHO, the prevalence in group 1 was 12.17% at inclusion, 2 months later 31.7%, and further 2 months later 65.71%, respectively. According to Achebe, the number of cases doubled; for group 1, the number of cases rose from 13 to 42 (115 patients total); for groups 2-4, we observed an increase from 112 to 230 (340 patients total). This study reported a prevalence of around 12% at the beginning of pregnancy, which increased during pregnancy up to 65%. ID can have a massive impact on quality of life, justifying screening, as iron deficiency would be easy to diagnose and treat.