eMedicine Specialties > Emergency Medicine > Obstetrics & Gynecology

Pregnancy, Asthma

Author: Markus Little, MD, Staff Physician, Department of Emergency Medicine, State University of New York Downstate Medical Center
Coauthor(s): Richard H Sinert, DO, Associate Professor of Emergency Medicine, Clinical Assistant Professor of Medicine, Research Director, State University of New York College of Medicine; Consulting Staff, Department of Emergency Medicine, Kings County Hospital Center
Contributor Information and Disclosures

Updated: Jun 30, 2009

Introduction

Background

Asthma is a chronic inflammatory disease of the airways that is characterized by increased responsiveness of the tracheobronchial tree to multiple stimuli. 

Asthma is an episodic disease of acute exacerbations intermingled with symptom-free periods. Most 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.

Asthma is classically divided into 2 distinct types: allergic (extrinsic) and idiosyncratic (intrinsic).

Allergic asthma is frequently associated with a personal and/or familial history of allergic diseases and high serum levels of immunoglobin E (IgE). Patients with this type of asthma often have positive skin reactions to intradermal airborne antigen injections and have a positive response to provocation tests involving inhalation of specific antigens.

In contrast, idiosyncratic asthma often has normal IgE levels and no familial or personal history of allergy.

Asthma is the most common chronic condition in pregnancy. Despite the frequently held notion that it is harmless, asthma can cause tremendous morbidity to both the fetus and the mother. In fact, severe and/or poorly controlled asthma has been associated with numerous adverse perinatal outcomes, including preeclampsia, pregnancy-induced hypertension, uterine hemorrhage, premature birth, congenital anomalies, fetal growth restriction, and low birth weight.

Asthma Resources from Medscape and eMedicine

On June 25, 2009, The American Thoracic Society and the European Respiratory Society jointly released new official standards on asthma evaluation for clinical trials and practice.1 The Medscape Medical News article, New Guidelines Issued for Asthma Assessment, has a more detailed discussion.

The American College of Obstetricians and Gynecologists has issued practice guidelines for the assessment and management of asthma during pregnancy.2

Pathophysiology

Pregnancy has a significant effect on the respiratory physiology of a woman. While the respiratory rate and vital capacity does not change in pregnancy, there is an increase in tidal volume, minute ventilation (40%), and minute oxygen uptake (20%) with resultant decrease in functional residual capacity and residual volume of air as a consequence of the elevated diaphragm. In addition, airway conductance is increased and total pulmonary resistance is reduced, possibly as a result of progesterone. 

The result of all of these physiologic changes is a hyperventilatory picture as a normal state of affairs in the later half of pregnancy. This results in the picture of a chronic respiratory alkalosis during pregnancy with a decreased pCO2, decreased bicarbonate, and increased pH. A normal pCO2 in a pregnant patient may signal impending respiratory failure. The increased minute ventilation and improved pulmonary function in pregnancy promote more efficient gas exchange from the maternal lungs to the blood. Therefore, changes in respiratory status occur more rapidly in pregnancy than in the nonpregnant patient.

Asthma is characterized by inflammation of the airways, with an abnormal accumulation of eosinophils, lymphocytes, mast cells, macrophages, dendritic cells, and myofibroblasts. This leads to a reduction in airway diameter caused by smooth muscle contraction, vascular congestion, bronchial wall edema, and thick secretions.

Frequency

United States

Prevalence of asthma in the general population is 4-5%. In pregnancy, the prevalence ranges from 1-4%.

International

Statistics are the same as in the United States.

Mortality/Morbidity

  • Morbidity and mortality rates of pregnant women with asthma are comparable to the general population.
  • The mortality rate from asthma in the United States is currently 2.1 per 100,000.
  • Death rates in the United States have been increasing from 0.8 per 100,000 in the general population in the late 1970s to 2.1 per 100,000 in 1994.3

Race

Prevalence and mortality rates are significantly higher in African Americans and Hispanics when compared with whites.

Sex

The male-to-female ratio in childhood is 2:1. That ratio decreases to 1:1 by 30 years.

Age

The prevalence of asthma is the same in all women of childbearing age.

Clinical

History

  • Cough
  • Shortness of breath
  • Chest tightness
  • Noisy breathing
  • Nocturnal awakenings
  • Recurrent episodes of symptom complex
  • Exacerbations possibly provoked by nonspecific stimuli
  • Personal or family history of other atopic disease (eg, hay fever, eczema)

Physical

  • Physical examination may be completely normal during remission.
  • Tachypnea
  • Retraction (sternomastoid, abdominal, pectoralis muscles)
  • Agitation, usually a sign of hypoxia or respiratory distress
  • Pulsus paradoxicus  (>20 mm Hg)
  • Pulmonary findings
    • Diffuse wheezes (long, high-pitched sounds on expiration and, occasionally, on inspiration)
    • Diffuse rhonchi (short, high- or low-pitched squeaks or gurgles on inspiration, expiration, or both)
    • Bronchovesicular sounds
    • Expiratory phase of respiration equal or more prominent than inspiratory phase
  • Signs of fatigue and near respiratory arrest
    • Alteration in the level of consciousness, such as lethargy, which is a sign of respiratory acidosis and fatigue
    • Abdominal breathing
    • Inability to speak in complete sentences
  • Signs of complicated asthma
    • Check for equality of breath sounds (pneumonia, mucous plugs, barotrauma). The amount of wheezing does not always correlate with the severity of the attack. A silent chest in someone in distress is more worrisome.
    • Jugular venous distension from increased intrathoracic pressure (from a coexistent pneumothorax)
    • Hypotension and tachycardia (think tension pneumothorax)
    • Fever, a sign of upper or lower respiratory infections

Causes

  • A complex and poorly defined interaction of genetic predisposition and environmental stimulation causes the asthma.
  • The basic mechanism for nonspecific bronchial hyper-responsiveness is unknown.
  • Airway inflammation is the most popular hypothesis.
  • Implicated environmental stimuli include the following:  
    • Allergens, including pollens, house-dust mites, cockroach antigen, animal dander, molds, and Hymenopteran stings
    • Irritants, including cigarette smoke, wood smoke, air pollution, strong odors, occupational dust, and chemicals
    • Medical conditions, including viral upper respiratory infections, sinusitis, esophageal reflux, and Ascaris infestations
    • Drugs and chemicals, including aspirin, nonsteroidal anti-inflammatory drugs, beta-blockers, radiocontrast media, and sulfites
  • Exercise
  • Cold air
  • Menses
  • Emotional stress

More on Pregnancy, Asthma

Overview: Pregnancy, Asthma
Differential Diagnoses & Workup: Pregnancy, Asthma
Treatment & Medication: Pregnancy, Asthma
Follow-up: Pregnancy, Asthma
References
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References

  1. [Guideline] Reddel HK, Taylor DR, Bateman ED, et al. An official American Thoracic Society/european Respiratory Society statement: asthma control and exacerbations: standardizing endpoints for clinical asthma trials and clinical practice. Am J Respir Crit Care Med. Jul 1 2009;180(1):59-99. [Medline].

  2. [Guideline] American College of Obstetricians and Gynecologists (ACOG). Asthma in pregnancy. ACOG practice bulletin; no. 90. Washington (DC): American College of Obstetricians and Gynecologists (ACOG). Feb 2008;[Full Text].

  3. Sly RM, O'Donnell R. Stabilization of asthma mortality. Ann Allergy Asthma Immunol. Apr 1997;78(4):347-54. [Medline].

  4. Hornby PJ, Abrahams TP. Pulmonary pharmacology. Clin Obstet Gynecol. Mar 1996;39(1):17-35. [Medline].

  5. Mabie WC. Asthma in pregnancy. Clin Obstet Gynecol. Mar 1996;39(1):56-69. [Medline].

  6. Mays M, Leiner S. Asthma. A comprehensive review. J Nurse Midwifery. May-Jun 1995;40(3):256-68. [Medline].

  7. Nelson-Piercy C, Moore-Gillon J. Asthma in pregnancy. Br J Hosp Med. Feb 7-20 1996;55(3):115-7. [Medline].

  8. Rey E, Boulet LP. Asthma in pregnancy. BMJ. Mar 17 2007;334(7593):582-5. [Medline].

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Further Reading

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Keywords

asthma in pregnancy, asthma, pregnancy, asthma guidelines, asthma assessment, asthma treatment, asthma symptoms, asthma causes, respiratory disease, asthmatic, wheeze, wheezing, noisy breathing, difficulty breathing, cough, allergy, allergic disease, reactive airway disease, bronchiolitis, bronchial asthma, acute asthma, allergies, bronchial airways, bronchial airway narrowing, inflammation of the bronchi, bronchial smooth muscle contraction, dyspnea, airway narrowing, allergic asthma, idiosyncratic asthma, treating asthma in pregnancy, maternal asthma, pulmonarydisease and pregnancy

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Contributor Information and Disclosures

Author

Markus Little, MD, Staff Physician, Department of Emergency Medicine, State University of New York Downstate Medical Center
Disclosure: Nothing to disclose.

Coauthor(s)

Richard H Sinert, DO, Associate Professor of Emergency Medicine, Clinical Assistant Professor of Medicine, Research Director, State University of New York College of Medicine; Consulting Staff, Department of Emergency Medicine, Kings County Hospital Center
Richard H Sinert, DO is a member of the following medical societies: American College of Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Assaad J Sayah, MD, Chief, Department of Emergency Medicine, Cambridge Health Alliance
Assaad J Sayah, MD is a member of the following medical societies: National Association of EMS Physicians
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Mark Zwanger, MD, MBA, Assistant Professor, Department of Emergency Medicine, Thomas Jefferson University
Mark Zwanger, MD, MBA is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and American Medical Association
Disclosure: Medicines Company Consulting fee Consulting; Pfizer Salary Employment

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Pamela L Dyne, MD, Professor of Clinical Medicine/Emergency Medicine, David Geffen School of Medicine at UCLA; Attending Physician, Department of Emergency Medicine, Olive View-UCLA Medical Center
Pamela L Dyne, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

 
 
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