Thrombocytopenia (low platelet count) in Pregnancy

What is Thrombocytopenia?

Thrombocytopenia – or low platelet count – is not uncommon, affecting about 8% of pregnancies. The majority of these cases are mild and don’t pose any problems to the woman or her baby. Thrombocytopenia has many causes. One of the most common causes of low platelets is a condition called immune thrombocytopenia (ITP). The two main causes of thrombocytopenia are a decrease in the production of platelets in the bone marrow and an increase in the destruction of the platelets.

Moreover, most pregnant women with ITP may have a history of thrombocytopenia prior to pregnancy or may present with other immune-mediated diseases.

Mild gestational thrombocytopenia is relatively frequent during normal pregnancy and generally has no consequences for either the mother or the fetus. Although with no real threat in the majority of patients, thrombocytopenia may result from a range of pathologic conditions requiring closer monitoring and possible therapy.

Two clinical scenarios are particularly relevant for their prevalence and the issues relating to their management. The first is the presence of isolated thrombocytopenia and the differential diagnosis between primary immune thrombocytopenia and gestational thrombocytopenia. The second is thrombocytopenia associated with preeclampsia and its look-alikes and their distinction from thrombotic thrombocytopenic purpura and the hemolytic uremic syndrome.

When diagnosed in pregnancy, the condition is called gestational thrombocytopenia. However, some women may have chronic cases of immune thrombocytopenia that went undiscovered until their routine prenatal blood tests. Preeclampsia occurs in 3 to 4% of pregnancies and accounts for 5 to 21% of cases of maternal thrombocytopenia.

What Does it Mean to Have Gestational Thrombocytopenia?

Platelets are blood cells that aid in clotting. Doctors measure platelets by the count per microliter of blood.

• Normal platelet count:150,000-400,000/microliter.
• Mild thrombocytopenia: 100,000-150,000/microliter.

Pregnant women tend to have higher rates of mild thrombocytopenia, but researchers aren’t really sure why that is. We know that a low platelet count results from the body’s tendency to use up or destroy platelets faster than it can produce them. It appears that pregnancy speeds up the blood’s natural renewal processes, but it’s not clear why this happens.

Some pregnant women already have a non-pregnancy-related type of thrombocytopenia, called immune thrombocytopenic purpura (ITP). Symptoms are bruising and purple spots on the skin caused by spontaneous bleeding.

Some medicines, such as the blood-thinning drug heparin, can also affect your platelet count. Maternal platelet count and antiplatelet antibodies do not predict the risk of neonatal thrombocytopenia. In some cases, the low platelet count may compromise the ability to deliver epidural anesthesia and general anesthesia represents a greater risk. The mother’s platelet levels will go back to a normal range 1–2 months after the delivery.

Additionally, some pregnant women go on blood thinners to treat other, more serious conditions. This type of therapy can affect your blood count. If you are being treated with blood thinners, your doctor will keep this in mind during your prenatal visits and will talk to you about managing your health. Despite remaining relatively stable through most of the pregnancy, platelet counts may fall during the third trimester, and monitoring should be more frequent.

The good news is that, typically, cases of gestational thrombocytopenia will disappear after delivery.

Severe Low Platelet Count During Pregnancy

A very low platelet count poses serious risks for pregnancy complications. For one, delivery becomes much more dangerous since the mother’s blood will have more difficulty clotting. Typically, you will develop gestational thrombocytopenia with each subsequent pregnancy.

If you develop moderate to severe gestational thrombocytopenia, your doctor will recommend having treatments during your pregnancy to stabilize the condition and to keep your baby safe. Delivery options and delivery modes will have to be discussed in the function of history and physical examination, gestational age, and severity of thrombocytopenia.

Severe thrombocytopenia increases a pregnant woman’s risk of heavy bleeding (hemorrhaging) during or after birth. It makes invasive medical procedures, like inserting an epidural or performing a Cesarean delivery, riskier. Gestational thrombocytopenia is not an indication for cesarean delivery and the mode of delivery (either cesarean or vaginal delivery) should be based on your OB/GYN’s considerations.

Sometimes, a severe case of thrombocytopenia is a symptom of a more serious underlying condition, such as lupus (an autoimmune disease) or HELLP syndrome (Hemolysis, Elevated Liver enzymes (fatty liver), and Low Platelet count syndrome), another pregnancy-specific disorder. Hypertensive disorders (preeclampsia, eclampsia, HELLP syndrome, and acute fatty liver of pregnancy) are the second leading cause of thrombocytopenia in pregnancy.

These complications are rare, but they are life-threatening. One, two, or three components of the disease have been described as a partial form of severe preeclampsia. The risk of severe morbidity correlates in general with increasingly severe thrombocytopenia. Disseminated intravascular coagulation (DIC) complicates up to 80% of severe cases. DIC has a number of causes, the most important being placental abruption, amniotic embolus, and uterine rupture. Von Willebrand disease type IIb is a rare cause of thrombocytopenia in pregnancy.

The IgG anti-glycoprotein platelet antibodies can cross the placenta and could induce neonatal thrombocytopenia. There is no correlation between maternal and fetal platelet levels, and maternal response to treatment does not protect the fetus from possible fetal thrombocytopenia.

Gestational Thrombocytopenia Treatments

A physical examination and a complete review of your family history will help the health care provider in making a proper diagnosis and management of thrombocytopenia in pregnancy.

Most mild cases of thrombocytopenia can be monitored without treatment. In all likelihood, the condition will disappear and no longer affect you or your baby after birth. Thrombocytopenia and elevated liver function tests commonly worsen postpartum. Platelets should start normalizing by the third postpartum day. You may have to take steroid tablets or have an infusion of a blood protein called globulin (IVIg). Alternatively, your doctor may recommend that you have a transfusion of platelets or plasma to increase the platelet levels in your blood.

Plasma exchange is the first-line treatment, and regular plasma exchange may enable pregnancy to continue successfully. In some cases of thrombocytopenia, unresponsive to alternative therapies, a splenectomy can safely be performed, especially in the second trimester of pregnancy.

Severe cases might require some invasive forms of treatment. The goal is to increase your platelet count and stabilize your condition to withstand the stress and trauma of delivery. Some treatments might include:

• Prescription (oral) steroids
• Intravenous immunoglobulin therapy – administration of immune globulin from donated plasma
• Platelet transfusion
• Plasma transfusion

Occasionally, a very low platelet count could be a sign of a problem with your pregnancy. This could be a rare complication of pre-eclampsia in late pregnancy, called HELLP syndrome, which also causes the following symptoms:

• pre-eclampsia symptoms, such as high blood pressure and protein in your urine
• pain when inhaling deeply
• severe headache
• nausea
• a sudden increase in swelling of the feet, ankles, hands, and face

If you have all these symptoms, call your health care provider right away.

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