Immune thrombocytopenia and pregnancy: an exposed/non-exposed cohort study.

The risk of immune thrombocytopenia (ITP) worsening during pregnancy and neonatal ITP (NITP) have never been prospectively studied. We included 180 pregnant and 168 non-pregnant ITP women in a prospective, multicenter, observational cohort study. 131 pregnant ITP women were matched to 131 non-pregnant ITP women by history of splenectomy, ITP status (no response, response, complete response) and duration. Groups were followed for 15 months. The primary outcome was the first occurrence of ITP worsening defined by a composite endpoint including bleeding events and/or severe thrombocytopenia (<30x109/L) and/or ITP treatment modification. We also studied the recurrence of ITP worsening and incidence of NITP and risk factors. The first occurrence of ITP worsening did not differ between pregnant and non-pregnant ITP women (53.4 per 100 person-years [95%CI, 40.8-69.9] vs. 37.1 [27.5-50.0]; hazard ratio [HR], 1.35 [95%CI, 0.89-2.03], p=0.16). Pregnant ITP women were more likely to have recurrence of severe thrombocytopenia and treatment modification (HR, 2.71 [95%CI, 1.41-5.23], p=0.003; HR, 2.01 [95%CI, 1.14-3.57], p=0.017, respectively). However, recurrence of severe bleeding events was not different between groups (p=0.4). Nineteen (14%) neonates showed NITP <50´109/L. By multivariable analysis, NITP was associated with a previous offspring with NITP and maternal platelet count <50´109/L within 3 months before delivery (adjusted odds ratio, 5.55 [95%CI, 1.72-17.89], p=0.004 and 4.07 [1.41-11.73], p=0.009). To conclude, ITP women do not increase their risk of severe bleeding during pregnancy. NITP is associated with NITP history and the severity of maternal ITP during pregnancy. These results will be useful for counseling ITP women.