Risks and Prevalence
Asthma is a chronic inflammatory disease of the airways that is characterized by increased responsiveness of the tracheobronchial tree to multiple stimuli. It is the most common chronic condition in pregnancy.
The disease is episodic, being characterized by acute exacerbations intermingled with symptom-free periods. Most asthma attacks prove to be short-lived, lasting minutes to hours. Although patients appear to recover completely clinically, evidence suggests that patients with asthma develop chronic airflow limitations.
The prevalence of asthma in the general population is 4-5%. In pregnancy, the prevalence ranges from 1-4%.
Asthma-related morbidity and mortality rates in pregnant women are comparable to those in the general population. The mortality rate from asthma in the United States is 2.1 persons per 100,000.
Outcomes and complications of asthma in pregnancy
Although women with mild asthma are unlikely to have problems, patients with severe asthma are at greater risk of deterioration. The deterioration risk is highest in the last portion of a pregnancy.
In fact, severe and/or poorly controlled asthma has been associated with numerous adverse perinatal outcomes, including the following:
Pregnancy-induced hypertension
Preterm labor
Congenital anomalies
Low birth weight
Neonatal hypoglycemia, seizures, tachypnea, and neonatal intensive care unit (ICU) admission
This risk of giving birth to a small or preterm infant appears to be small and may be minimized by good control of asthma. Studies have indicated that low-birth-weight infants are more common in women with daily symptoms or low expiratory flow than in women without asthma.
Asthma can also lead to the following morbidities in pregnant women:
Respiratory failure and the need for mechanical ventilation
Barotrauma
Complications of (parenteral) steroid use
Death can also occur.