The primary purpose of this study is to get explorative information about IV high single dose infusion of iron isomaltoside 1000 compared to RBC transfusion in the treatment of severe PP-IDA evaluated as physical fatigue

Inclusion Criteria:

1. PPH > 1000 mL
2. Hb ≥ 5.5 and ≤ 8.0 g/dL (≥ 3.5 and ≤ 5.0 mmol/L)
3. Willingness to participate and signed the informed consent form

Exclusion Criteria:

1. Women aged < 18 years
2. Multiple births
3. Peripartum RBC transfusion
4. Known iron overload or disturbances in utilisation of iron (e.g. haemochromatosis and haemosiderosis)
5. Known hypersensitivity to parenteral iron or any excipients in the investigational drug products
6. Women with a history of active asthma within the last 5 years or a history of multiple allergies
7. Known decompensated liver cirrhosis and active hepatitis
8. Women with HELLP (Haemolysis Elevated Liver enzymes Low Platelet count) syndrome (defined according to "Dansk Selskab for Obstetrik og Gynækologi guidelines")
9. Active acute infection assessed by clinical judgement
10. Rheumatoid arthritis with symptoms or signs of active joint inflammation
11. History of anaemia caused by e. g. thalassemia, hypersplenism or haemolytic anaemia (known haematologic disorder other than iron deficiency)
12. Not able to read, speak and understand the Danish language
13. Participation in any other clinical study where the study drug has not passed 5 half-lives prior to the baseline
14. Any other medical condition that, in the opinion of Investigator, may cause the patient to be unsuitable for completion of the study or place the patient at potential risk from being in the study. For example, a malignancy, uncontrolled hypertension, unstable ischaemic heart disease or uncontrolled diabetes mellitus