Pulmonary embolism in pregnancy

By trimester

Weeks 1–13

1st trimester

Pulmonary embolism can occur in any trimester. Sudden breathlessness, pleuritic chest pain, coughing blood, or fainting needs emergency assessment even early in pregnancy. Pregnancy-adapted pathways may avoid chest imaging in selected patients, but only after structured clinical testing.

Weeks 14–27

2nd trimester

New one-sided leg swelling, pain, warmth, or redness can signal deep vein thrombosis, the usual source of pulmonary emboli. Compression ultrasound can identify a leg clot and may establish the need for care without chest imaging in some cases.

Weeks 28–birth

3rd trimester

Clot risk rises around birth and remains elevated postpartum. Do not dismiss sudden chest symptoms as the mechanical breathlessness of late pregnancy. Imaging choice depends on the clinical pathway, chest findings, local expertise, and test availability.

What does the evidence show for pulmonary embolism?

• Pregnancy raises venous blood clot risk about fivefold, and the elevated risk continues through three months after birth. CDC lists sudden difficulty breathing, chest pain worsened by a deep breath or cough, coughing blood, and a fast or irregular heartbeat as pulmonary embolism warning signs requiring immediate care. 1
• Pulmonary embolism is a sudden blockage in a lung artery and can be life-threatening. Shortness of breath, rapid breathing, pleuritic chest pain, rapid heartbeat, coughing blood, low blood pressure, lightheadedness, or fainting are recognized symptoms, but no symptom alone confirms or excludes it. 2
• In a prospective study of 498 pregnant patients with suspected pulmonary embolism, a pregnancy-adapted YEARS pathway used three clinical criteria, D-dimer thresholds, and leg ultrasound when DVT signs were present. Three-month follow-up found one DVT and no pulmonary embolism among those ruled out, while chest CT was avoided in 39 percent. 3
• A systematic review and meta-analysis found similar very low pooled false-negative rates after negative CT pulmonary angiography or ventilation-perfusion scanning in pregnancy. Nondiagnostic results occurred with both tests, and substantial heterogeneity and risk of bias limited direct comparison. 4
• Pregnancy-related DVT warning signs include swelling, pain or tenderness, warmth, and redness or discoloration, usually in one limb. A clot can travel to the lungs, so new unilateral leg findings need prompt assessment and chest symptoms need emergency care. 1

When should I call my provider about pulmonary embolism?

Call emergency services for sudden or worsening shortness of breath, chest pain that worsens with breathing or coughing, coughing blood, a fast or irregular heartbeat, severe lightheadedness, collapse, or fainting. New one-sided leg swelling, pain, warmth, or redness needs prompt same-day assessment because it can signal a deep vein clot that may travel to the lungs. Whatever the pattern, any symptom that feels beyond your usual range is a reason to call: obstetric teams expect these questions and would rather hear early than late.