Thrombocytopenia is relatively common during pregnancy. There are 3 conditions that can be considered during pregnancy:
- Gestational Thrombocytopenia: this is a condition in which the mother becomes thrombocytopenic with every pregnancy. It is sometimes referred to as "physiological thrombocytopenia" and is not believed to be immune mediated. The mother's platelet level does not normally reach sufficient low levels to cause significant hemorrhage.
- Incidental Thrombocytopenia of pregnancy: this situation arises when a female patient with ITP becomes pregnant. In this situation both the mother and the infant may become thrombocytopenic since the IgG antibodies generated by the Immune Thrombocytopenic Purpura can readily cross the placenta.
- Allo-Immune Thrombocytopenia: a condition similar to Hemolytic Disease of the Newborne (Rh sensitization) in which through placental hemorrhages, the mother becomes sensitized to an antigen found on the baby's platelets. The mother becomes sensitized to the baby's platelets during the first pregnancy and will product antibodies which cross the placenta and destroy the fetal platelets in subsequent pregnancies. In this situation, the mother is not affected and she has a normal platelet count. Only the unborn child is affected. Up to 5% of these affected fetuses my succumb to intra-uterine death from hemorrhage.
- Clinical studies in treatment of ITP during pregnancy have not been performed
This shows the Incidence of the types of Thrombocytopenic Purpura during Pregnancy Thrombocytopenia in Pregnancy (n=15,000) |
|
| Gestational Thrombocytopenia | 74% |
| Hypertension in pregnancy (PET) | 21% |
| Immune (Allo-Immune thrombocytopenia) | 4% |
| Other | 1% |
Burrows, Kelton NEJM 329:1463:1992
Antepartum
Maternal risk is generally low. Most of the pregnant women go through the pregnancy without any therapy. However, therapy could be required if there is a thrombocytopenia below 50x109/L , or hemorrhagic syndromes (easy bruising, petechiae).
Epidural anesthesia is generally not allowed if the platelet count is <80.109/L
Delivery
Controversies still exist concerning the best way of delivery to avoid intracerebral hemorrhages (ICH) for severely thrombocytopenic fetuses. C-section is advocated to avoid ICH. Vaginal delivery has been suggested to bear a higher risk of intracranial hemorrhage. There are no prospective studies showing that Cesarean section is more effective or less risky for the mother or neonate.
Fetus and the New Born
There should be close monitoring of the platelet counts of the new born after birth, at 24 hours and at days 3 and 5. In case of severe thrombocytopenia or hemorrhagic syndromes IVIg 1g/kg/d has been used. Breast-feeding is not discouraged.
The tables below show the severity of thrombocytopenia in over 1500 newborn infants.
| Risk to Fetus/Infant Retrospectice plus prospective studies 1990-2000 |
|
| Neonatal platelets < 50 | 8% |
| Neonatal platelets < 20 | 2% |
| Immune (Allo-Immune thrombocytopenia) | 1-2% |
Gill, Kelton , Semin. Hematol. 37:275:2000
