Thrombocytopenia means "low platelets", the cells that circulate within our blood and clot or bind together when they recognize damaged blood vessels. Usually a normal platelet count is in the range of 150,000 to 450,000/microL during normal pregnancies, though occasionally may be slightly lower in pregnancy, on average, than in healthy, non-pregnant women.
Thrombocytopenia occurring during pregnancy is a common diagnostic and management problem occuring in up to 10% of all pregnancies and may have many causes.

Gestational Thrombocytopenia

The most common cause of thrombocytopenia in pregnancy in approximately 75% of all cases is so called "gestational thrombocytopenia".  Platelets normally fall in pregnancy and the reason for this decline is not known and some believe it has to do with less platelt production in pregnancy of dilution of platelets. Pregnant women with mild gestational thrombocytopenia first devlop this condition after the 24th week of the pregnancy. When the platelet count falls below 70-80,000/
L then the diagnosis is less likely gestational thrombocytopenia and other causes should be explored.

There is no specific test available for gestational thrombocytopenia, so it is a  a diagnosis of exclusion.●Thrombocytopenia discovered incidentally during a normal pregnancy and its distinction from immune thrombocytopenia (ITP)

Causes of thrombocytopenia in pregnancy

 

Pregnancy-specific thrombocytopenia

• Gestational thrombocytopenia (75% of all cases)
• Preeclampsia/Eclampsia
• HELLP syndrome
• Acute fatty liver

Not pregnancy-specific thrombocytopenia

• Primary immune thrombocytopenia (ITP)
• Secondary immune thrombocytopenia
• Viral infection (HIV, Hep C, C MV, EBV, ot hers)
• Autoimmune disorders (SLE, others)
• Antiphospholipid antibodies
• Thrombotic microangiopathies
• Thrombotic thrombocytopenic purpura*
• Hemolytic-uremic syndrome*
• Disseminated intravascular coagulation (DIC)
• Bone marrow (MDS, myelofibrosis)
• Nutritional deficiencies
• Drugs
• Type IIB vWD induced thrombocytopenia*
• Inherited thrombocytopenia (May-Hegglin, etc)
• Hypersplenism

However, in many cases, it may not be possible to distinguish gestational thrombocytopenia, particularly a more
severe case, from ITP.

Outcome of thrombocytopenia in pregnancy

The outcome depends on what causes the thrombocytopenia and how severe it is. Gestational thrombocytopenia with only mildly decreased platelet count is not associated with adverse outcomes
Gestational thrombocytopenia is self-limited and resolves
within 1 to 2 months after delivery.