Effect of pregnancy on the course of immune thrombocytopenia: a retrospective study of 118 pregnancies in 82 women

In women with pre-existing immune thrombocytopenic purpura (ITP), the effect of pregnancy on the course of the disease is poorly known. We performed a dual-centre retrospective cohort study of 118 pregnancies in 82 women with primary ITP. In early pregnancy, the platelet count was <100 x 10(9)/l in 35.6% of pregnancies. During pregnancy the median platelet count nadir was 66 x 10(9)/l (25th-75th percentile: 42-117), with platelet count <30 x 10(9)/l for 26 pregnancies (22%). In 49% of pregnancies, a significant decrease of the platelet count required treatment at least transiently in preparation for delivery. At the time of delivery, the median platelet count was 110 x 10(9)/l (77-155). Compared to before pregnancy, at 3 months post-partum, only 11% of pregnancies [95% confidence interval (95% CI): 6.8-20.2] showed disease worsening. Previous splenectomy was the only factor significantly associated with ITP worsening after pregnancy (53.9% vs. 10.3%, P < 0.001). For 8.3% of the pregnancies (95% CI: 3.8-15.1), neonatal thrombocytopenia required treatment, especially in case of previous maternal splenectomy (adjusted odds ratio 16.7, 95% CI: 2.61-106). The overall risk of exacerbation of ITP and severe thrombocytopenia during pregnancy is acceptable.