[Pregnancy-related thrombocytosis]

Pregnancy-related thrombocythaemia comprises myeloproliferative and inflammatory reactive subsets. In pregnant women treated for myeloproliferative disorders, especially polycythaemia vera and primary thrombocytosis, only 50-70 per cent are delivered successfully of a normal healthy baby. The maternal complications are cerebral, cardiac, and abdominal arterial thrombosis, and with deep venous thrombosis of the legs, whereas bleedings are mainly seen in the case of extreme thrombocythaemia, owing to absorption of factors by the platelets. The foetal complication are dominated by abruptio placentae, pre-eclampsia, placental insufficiency, and death. Reactive thrombocythaemia includes the physiological rise in platelets postpartum, believed to be part of the normal maternal haemostasis, which almost never causes thromboembolic complications, as far as is known today. In contrast, the inflammatory reactive thrombocythaemia, related to severe foetal and/or maternal necrosis, is generally related only to a moderate rise in the platelet count. As the blood-platelet count does not appear to be routine at general pregnancy check-ups, it is necessary to be aware of risk groups, consisting of women with otherwise unexplained abortions or stillbirths, unexplained foetal and placental malformations, and pre-eclampsia, even if the woman has never had any thromboembolic complications.