We report a case of a previously fit woman who presented at 26 weeks into her fourth pregnancy with a dry cough. Following a nasopharyngeal swab, she was diagnosed with a pertussis infection, and treated with antibiotics. A chest X-ray showed right atrial dilatation and an echocardiogram was scheduled outpatient. However, after re-presenting with worsening cough and dyspnoea, an inpatient echocardiogram was performed which suggested elevated pulmonary pressures with significant tricuspid regurgitation, as confirmed by subsequent cardiac catheterisation. She had an elective caesarean section at 34 weeks and underwent repeat right heart catheterisation which revealed persistent, and likely pre-existing, pulmonary arterial hypertension. This case highlights the importance of thorough assessment of non-obstetric symptoms in pregnancy in formulating alternative differentials, even after a diagnosis has been made, to prevent potentially life-threatening conditions from being missed. It also shows that although often associated, respiratory and cardiac causes may coexist separately.