Fertility, pregnancy and the management of myeloproliferative disorders.

The management of pregnant patients with chronic myeloproliferative disorders (MPD) is a difficult problem. Patients with essential thrombocythaemia (ET), and, less frequently, those with chronic myeloid leukaemia (CML) or polycythaemia vera (PV), present at a childbearing age. Pregnancy itself does not appear to affect adversely the natural course and prognosis of the MPD. However, fertility might be reduced, and an adverse outcome of pregnancy due to thrombotic or bleeding complications is a matter of concern. It ET, first-trimester abortion is the most frequent complication but increased perinatal mortality and premature delivery are also observed. Placental infarction due to thrombosis seems to be the most consistent event. Maternal thrombotic or haemorrhagic complications are rare but are more common than seen in normal pregnancy. The outcome of pregnancy seems to be positively influenced by aspirin, at least in some cases. The value of cytoreduction and/or heparin prophylaxis has not been established but may have a role in selected cases. In CML, the potential adverse effects of hyperleukocytosis, and sometimes thrombocytosis, generally make myelosuppressive treatment essential. In PV, the number of reported pregnancies is low. Maintaining the PCV below 0.45 is of the utmost importance relating to the outcome of pregnancy. Although cytoreductive drugs should generally be avoided, if possible, until at least after the first trimester of pregnancy, interferon-alpha seems to be the drug of choice when myelosuppression is indicated. In summary, the available information about pregnancy occurring during the course of an MPD indicates that successful management of pregnancy is possible. However, optimal management of these patients is poorly defined and agreed protocols are not available. In view of these problems, it is timely to consider the establishment of a national or European registry to monitor prospectively the management offered to pregnant women found to have an MPD.