What is the best approach to manage a 28-week pregnant woman with mild shortness of breath (SOB) on exertion, normal examination, and no pre-existing medical conditions?

Management of Mild Exertional Dyspnea at 28 Weeks Gestation

Reassurance is the appropriate initial management for this patient, as mild shortness of breath on exertion with a normal physical examination represents a common physiological adaptation to pregnancy and does not require further diagnostic workup or treatment. 1, 2

Understanding Normal Physiological Changes

Pregnancy induces substantial cardiopulmonary adaptations that commonly manifest as exertional dyspnea:

• Oxygen consumption increases by approximately 40% by 8-11 weeks gestation (from 182 ml/min to 256 ml/min), peaking at 300 ml/min by 32 weeks, which explains the sensation of breathlessness during activity 3

• Minute ventilation increases by 30-40% due to elevated tidal volume (from 563 ml to 715 ml), while respiratory rate remains unchanged, creating the subjective sensation of dyspnea despite adequate oxygenation 3

• Cardiac output increases by 50% by early pregnancy and remains elevated, with heart rate rising from 80 to 90 bpm by the third trimester 3

• These changes are normal adaptations to meet increased metabolic demands and do not indicate pathology when the physical examination is normal 1, 2

Critical Red Flags That Require Immediate Evaluation

Before providing reassurance, you must actively exclude concerning features that would indicate pathologic causes:

Symptoms requiring urgent workup:

• Severe dyspnea at rest (not just with exertion) 1
• Chest pain, particularly pleuritic chest pain 1
• Hemoptysis 1
• Syncope or presyncope 1
• Palpitations or unexplained hypotension 1

Physical examination findings requiring further investigation:

• Oxygen desaturation with exertion (SpO2 <95%) 1
• Tachypnea at rest (>20 breaths/min) 1
• Persistent tachycardia 1
• Abnormal lung auscultation (crackles, wheezing, decreased breath sounds) 1
• Unilateral leg swelling (concerning for DVT) 1

Why Pulmonary Embolism Must Be Considered

Pulmonary embolism is the leading cause of pregnancy-related maternal death in developed countries, with an incidence of 1 per 1000 to 1 per 3000 deliveries 1. Pregnancy creates a hypercoagulable state through increased coagulation factors and decreased venous flow from uterine compression 1. However, in a patient with mild exertional dyspnea and a normal examination, PE is unlikely and diagnostic workup is not indicated 1, 2.

Diagnostic Testing Is NOT Indicated

• Chest X-ray is not appropriate as first-line management when the physical examination is normal and there are no concerning features 1

• Pulmonary function testing is reserved for patients with severe respiratory disorders such as COPD, severe asthma, cystic fibrosis, or restrictive lung disease—not for physiologic dyspnea of pregnancy 2

• The American College of Obstetrics and Gynecology clearly states that radiography should not be withheld when clinically indicated, but equally important is avoiding unnecessary radiation exposure when not indicated 4

Patient Counseling and Activity Recommendations

Patients with mild exertional dyspnea and normal examination should be encouraged to maintain moderate-vigorous physical activity without restriction 1, 2. This is a critical point because:

• Regular physical activity during pregnancy improves cardiovascular function, limits excessive weight gain, decreases musculoskeletal discomfort, and reduces the incidence of gestational diabetes and hypertension 5

• Physical activity does not harm the fetus and may provide fetal benefits including decreased fat mass and improved stress tolerance 5

• Many women inappropriately stop exercising after discovering pregnancy, which may contribute to hypertension, obesity, and gestational diabetes 5

Specific instructions to provide:

Seek immediate medical care if any of the following develop:

• Chest pain 1
• Severe dyspnea at rest (not just with exertion) 1
• Palpitations or syncope 1
• Signs of fluid overload (leg swelling, orthopnea) 1

Continue normal activities:

• Maintain regular physical activity as tolerated 1, 2
• No activity restrictions are necessary 2

Follow-Up Plan

• Routine prenatal follow-up is sufficient to reassess symptoms and ensure no progression 2

• No specialized monitoring or additional testing is required unless symptoms worsen or red flag features develop 1, 2

Common Pitfall to Avoid

The major pitfall is over-investigating physiologic dyspnea of pregnancy, which can lead to unnecessary radiation exposure, patient anxiety, and healthcare costs 4. Conversely, failing to recognize red flag features that warrant investigation for PE or other serious conditions represents the opposite extreme. The key is a thorough history and physical examination focusing on the specific red flags outlined above, followed by reassurance when these are absent 1, 2.