Introduction

It is a chronic reversible obstructive inflammatory disease of airways caused by constriction of bronchial smooth muscles causing bronchospasm, oedema of bronchial mucous membrane and blockage of the smaller bronchi with plug of mucous. 

It is characterized by increased sensitivity of the tracheobronchial tree to many varieties of allergens. Asthma is episodic with acute exacerbations and in between symptom-free periods.

Asthma in pregnancy worsens commonly between gestational age of 29 to 36 weeks and improvement occurs gradually over the pregnancy. The condition goes back to normal after puerperium.