This chapter describes the management of the more common classical Philadelphia negative myeloproliferative disorders (MPDs); primary thrombocythemia (PT), polycythemia vera (PV), and myelofibrosis (PMF) in pregnancy. It summarizes the epidemiology, pathogenesis, and diagnosis of the MPDs in pregnancy and a management strategy developed from current experience attained in a tertiary referral center. MPDs result from the transformation of a hematopoietic progenitor cell and are characterized by overproduction of mature blood cells. The diagnosis of MPDs in pregnancy requires an increased awareness of these disorders occurring in pregnant women. The chapter details local policy including adaptation for diagnostic investigations in pregnancy. A risk assessment according to disease status, concomitant illnesses, and prior obstetric history forms the basis for a discussion of the risks and benefits of therapeutic options in pregnancy. The chapter includes a series of challenging cases, which enable discussion of management options accordingly in these women with complex pregnancies.