Obstetric Haematology concerns the care of women before, during and after pregnancy with primary or secondary haematological disease. This is a high-stakes area of medicine where careful planning involving the multidisciplinary team and attention to detail can make the difference between life and death of a young woman and/or her baby. Normal pregnancy is associated with substantial physiological changes to meet the needs of the developing foetus but these changes, particularly if unbalanced, can themselves lead to complications. For example, the massive increase in uterine blood flow and vascular compliance necessary to maintain blood supply to the foetus can lead to significant haemorrhage at the time of placental separation. Changes in coagulation factors help to mitigate this risk but increase the potential for systemic thromboembolic events. The increased demand for iron and other nutrients by the growing foetus frequently results in maternal deficiencies and close proximity of the foetal and maternal circulations enables an effective transfer of nutrients and oxygen but exposes the mother to foetal antigenic material with potential alloimmune sensitization. Although most pregnancies progress without problem, knowledge and awareness in this field of medicine are critical to prevent avoidable complications.