Approximately 7% of healthy pregnant women have mild to moderate thrombocytopenia (platelet count 80 to 150 × 10⁹ per liter). Neither these women nor their offspring manifest abnormal bleeding. This condition has been designated incidental thrombocytopenia of pregnancy and requires no treatment.

Idiopathic Thrombocytopenic Purpura. Idiopathic thrombocytopenic purpura (ITP) is a common autoimmune disorder in which patients form antiplatelet autoantibodies against platelet-specific antigens. The condition frequently affects young women; consequently, one can anticipate that many patients with ITP will become pregnant while their illness is active. The major concern during pregnancy is whether infants born to mothers with ITP are at risk of serious bleeding during delivery and whether they can be identified before delivery.

Unfortunately, it has been determined that there is no relationship between maternal platelet count and the infant’s platelet count. Similarly, measurement of platelet-associated IgG on maternal platelets does not predict neonatal thrombocytopenia. In a prospective series of more than 7000 women, Burrows found that severe thrombocytopenia at the time of delivery occurs in less than 5% of infants. Moreover, Burrows found that one of the best predictors of severe neonatal thrombocytopenia is a previously affected infant. Thus the type of delivery should be decided solely on obstetric indications. After delivery a fetal cord platelet count should be obtained immediately and the infant’s platelet count followed carefully over the next week. Maternal indications for treatment of thrombocytopenia should not differ from those for nonpregnant individuals.

Disseminated Intravascular Coagulation. Disseminated intravascular coagulation (DIC) is associated with a number of complications of pregnancy. Abruptio placenta, amniotic fluid embolus, severe preeclampsia, retained dead fetus, sepsis, and second-trimester abortion can all be associated with DIC. Treatment of the underlying disease, including delivery, is the mainstay of therapy.

Von Willebrand’s Disease. Von Willebrand’s disease encompasses a group of inherited disorders of platelet function and factor VIII activity. Transfusions of cryoprecipitate or specific clotting factors are necessary if measured factor VIII activity falls below 50% during labor. Patients with type I von Willebrand’s disease may also respond favorably to treatment with desmopressin.