Thrombocythaemia and recurrent miscarriage

The incidence of thrombocythaemia (a platelet count >600×l0⁹/l) in a 10‐year survey was 7 per 10⁶ population per year (R. M. Pettit, personal communication). It is generally a disease of late middle age, but a second population of young and mainly female patients has been described (Hoagland & Silverstein 1978). An increased platelet count can be secondary (after splenec‐tomy, associated with inflammation, malignancy or iron deficiency) or due to a primary myeloproliferative disorder. We describe four patients in whom a series of miscarriages before 20 weeks gestation appears associated with thrombocythaemia and estimate the prevalence of this association in patients with unexplained repeated miscarriage.