Coagulation disorders affect the body's ability to form blood clots and control bleeding. During pregnancy, the blood naturally becomes more prone to clotting to help prevent excessive blood loss during childbirth. However, changes in the clotting system can increase the risk of complications in some women, particularly those with inherited bleeding disorders, thrombophilia or a history of abnormal blood clots.

Pregnancy-related hematology care focuses on identifying these risks, monitoring blood health and coordinating treatment to protect both the mother and the baby.

What Are Coagulation Disorders?

Coagulation is the process through which blood forms a clot to stop bleeding after an injury. It involves platelets, clotting proteins and other components of the blood.

A coagulation disorder occurs when this process does not function properly. Blood may clot too easily, increasing the risk of thrombosis, or fail to clot adequately, leading to excessive bleeding.

The two broad categories are:

• Clotting disorders: Conditions that increase the tendency to form abnormal blood clots.

• Bleeding disorders: Conditions that impair normal clot formation and increase the risk of prolonged or spontaneous bleeding.

Pregnancy can influence both types of conditions and may require specialised care.

How Does Pregnancy Affect Blood Clotting?

During pregnancy, several clotting factors increase while the body's natural anticoagulant and clot-dissolving mechanisms also change. These adaptations help prepare the body for delivery but increase the risk of venous thromboembolism, which includes deep vein thrombosis (DVT) and pulmonary embolism (PE).

The risk remains elevated after childbirth, particularly during the first six weeks postpartum. Additional factors, such as a previous blood clot, prolonged immobility, caesarean delivery, obesity or certain inherited conditions, may increase the risk further.

Common Coagulation Disorders During Pregnancy

1. Thrombophilia

Thrombophilia refers to an increased tendency to develop blood clots. It may be inherited or acquired.

Examples include factor V Leiden, prothrombin gene mutations and deficiencies of certain natural anticoagulants. Antiphospholipid syndrome is an acquired autoimmune condition associated with blood clots and specific pregnancy complications.

Not every woman with thrombophilia requires medication during pregnancy. Management depends on the specific condition, personal and family history, and overall risk of thrombosis.

2. Deep Vein Thrombosis (DVT)

DVT occurs when a blood clot forms in a deep vein, usually in the leg. Pregnancy-related changes in circulation and clotting can increase the risk.

Symptoms may include:

• wSwelling in one leg

• Pain or tenderness in the calf or thigh

• Warmth or redness in the affected area

Sudden breathlessness, chest pain, coughing up blood or collapse may indicate a pulmonary embolism and require emergency medical attention.

3. Von Willebrand Disease

Von Willebrand disease is an inherited bleeding disorder caused by a deficiency or dysfunction of von Willebrand factor, a protein involved in platelet adhesion and the protection of clotting factor VIII.

Some clotting-related measurements improve during pregnancy, but levels can fall after delivery. This may increase the risk of postpartum bleeding, making advance planning important.

4. Haemophilia Carriers and Other Inherited Bleeding Disorders

Women who carry haemophilia-associated genetic variants may have reduced clotting factor levels and experience bleeding symptoms. Other inherited bleeding disorders can also affect pregnancy and delivery.

Assessment may include clotting factor measurements, family history and genetic counselling where appropriate.

Pregnancy-Related Hematology Issues Beyond Coagulation

1. Anaemia During Pregnancy

Anaemia occurs when the blood does not have enough healthy red blood cells or haemoglobin to carry oxygen efficiently. Iron deficiency is a common cause during pregnancy, although folate or vitamin B12 deficiency and inherited blood disorders can also contribute.

Symptoms may include fatigue, dizziness, weakness and breathlessness. Diagnosis typically involves a complete blood count and, where appropriate, iron studies and additional tests to identify the cause.

2. Thrombocytopenia During Pregnancy

Thrombocytopenia refers to a lower-than-normal platelet count. It may occur as a relatively common, mild pregnancy-related change or be associated with conditions such as immune thrombocytopenia (ITP), pre-eclampsia or HELLP syndrome.

The cause, severity and trend in platelet count help determine whether monitoring or treatment is necessary, particularly before delivery or an epidural.

3. Antiphospholipid Syndrome (APS)

Antiphospholipid syndrome is an autoimmune condition associated with abnormal blood clot formation and certain pregnancy complications, including recurrent pregnancy loss in some patients.

Diagnosis requires appropriate clinical findings and specific laboratory tests. Management may involve specialist-directed anticoagulation and other treatment, depending on the patient's history and diagnostic criteria.

4. Postpartum Haemorrhage and Bleeding Risks

Postpartum haemorrhage is excessive bleeding after childbirth. It can result from obstetric causes, but an underlying bleeding disorder may contribute in some cases.

Women with von Willebrand disease, haemophilia-related factor deficiencies or other bleeding disorders may need a personalised delivery and postpartum care plan. Some clotting factor levels that rise during pregnancy fall after delivery, increasing the risk of delayed bleeding.

How Are Coagulation Disorders Diagnosed During Pregnancy?

Diagnosis depends on the suspected condition and may involve:

• Complete blood count: Evaluates haemoglobin, white blood cells and platelet levels.

• Coagulation tests: Prothrombin time (PT), activated partial thromboplastin time (aPTT) and other tests when indicated.

• Specific clotting factor assays: Assess individual clotting proteins when a bleeding disorder is suspected.

• Thrombophilia testing: Considered in selected patients based on their personal and family history and whether results would affect management.

• Antiphospholipid antibody testing: Used when APS is suspected.

• Imaging: Ultrasound or other appropriate imaging may be used when a blood clot is suspected.

Pregnancy naturally changes several blood and clotting measurements, so results must be interpreted in context. Some tests for inherited bleeding disorders may need reassessment outside pregnancy for an accurate diagnosis.

Treatment and Management During Pregnancy

Treatment is tailored to the specific disorder, the stage of pregnancy, the mother's history and the risks to both mother and baby.

Anticoagulation Therapy

Women with an acute blood clot or selected patients at high risk of thrombosis may require anticoagulant treatment. Low-molecular-weight heparin is commonly used during pregnancy when anticoagulation is indicated. Preventive treatment is not necessary for every woman with a thrombophilia; decisions depend on individual risk assessment.

Management of Bleeding Disorders

Treatment may include specific clotting factor replacement, desmopressin for selected patients, antifibrinolytic medicines or other specialist-directed therapies. The choice depends on the diagnosis, factor levels and clinical circumstances.

Delivery Planning

A coordinated plan helps the obstetrician, haematologist and anaesthetist prepare for labour, delivery, anaesthesia and potential bleeding or clotting complications.

For women with inherited bleeding disorders, planning should also consider whether the baby could inherit the condition and whether special precautions are needed during delivery.

Postpartum Monitoring

Care should continue after childbirth because the risk of venous blood clots remains elevated and some bleeding disorders can cause delayed postpartum haemorrhage. The need for anticoagulation, clotting factor support and follow-up should be assessed individually.

When Should You Consult a Haematologist?

A haematology consultation may be helpful if you:

• Have a personal history of blood clots or a strong family history of thrombosis.

• Have been diagnosed with a bleeding disorder or thrombophilia.

• Experience unexplained bruising, recurrent bleeding or persistently abnormal blood counts.

• Have recurrent pregnancy loss or pregnancy complications that may warrant evaluation for a blood disorder.

• Need guidance on anticoagulants, clotting factor treatment or delivery planning.

Sudden breathlessness, chest pain, one-sided leg swelling or heavy bleeding during pregnancy or after delivery requires urgent medical assessment.

Conclusion

Coagulation disorders and pregnancy-related hematology issues require careful evaluation because pregnancy changes the body's normal clotting balance. Conditions such as thrombophilia, von Willebrand disease, thrombocytopenia and anaemia may need different approaches to monitoring and treatment.

Early diagnosis, individualised risk assessment and coordinated care between haematologists and obstetric specialists can help reduce complications and support safer pregnancy, delivery and postpartum recovery.