This paper discusses different aspects of calcium homeostasis in pregnancy: the calcium demands of the mother, regulation mechanisms and the risk factors for demineralization. Special care should be paid to patients lying in bed for long periods and patients given heparin prophylaxis. One to two grams of calcium and 400 IU of vitamin D daily should be given orally to patients who are being treated for deep vein thrombosis. In addition, bone density should be checked to detect osteoporosis. The period of heparin prophylaxis must be as short as possible and bed rest must not be unnecessarily prolonged.