Asthma during pregnancy is an atopic bronchospastic respiratory disease that occurred during gestation or existed earlier and can affect its course. It is manifested by attacks of characteristic suffocation, unproductive cough, shortness of breath, noisy wheezing. It is diagnosed using physical examination methods, laboratory determination of markers of allergic reactions, spirography, peak flowmetry. For basic treatment, combinations of inhaled glucocorticoids, antileukotrienes, beta-agonists are used, short—acting bronchodilators are used to relieve seizures.
Bronchial asthma (BA) is the most common pathology of the respiratory system during pregnancy, it occurs in 2-9% of patients. According to the observations of obstetricians-gynecologists and pulmonologists, the progression of the disease is noted in 33-69% of pregnant women. At the same time, some women’s condition remains stable and even improves. Mild forms of BA are diagnosed in 62% of women, moderate — in 30%, severe — in 8%. Although an exacerbation of the disease is possible at any stage of pregnancy, it most often occurs in the second trimester, and during the last 4 weeks, spontaneous improvement usually occurs due to an increase in the content of free cortisol. The relevance of timely diagnosis of blood pressure (BP) is associated with the almost complete absence of complications with proper drug control.
The occurrence of the disease in a pregnant woman is provoked by the same factors as in non-pregnant patients. A significant role in the development of bronchial asthma is played by atopy — a hereditary predisposition to allergic diseases due to hypersensitivity of the body with enhanced synthesis of immunoglobulin (IgE). The starting point of bronchospastic conditions in these cases is the action of external triggers — household allergens (dust, paintwork vapors, building materials), plant pollen, animal hair, food, pharmaceuticals, tobacco smoke, occupational hazards, etc. The appearance of symptoms in predisposed pregnant women can be triggered by respiratory viral infections, chlamydia, Mycobacterium tuberculosis, intestinal and other parasites.
The topic of the effect of changes during gestation on the occurrence and course of BP is still considered insufficiently studied. According to various authors in the field of obstetrics, in some cases the onset of the disease is associated with pregnancy, and its symptoms may persist or disappear completely after childbirth. A number of neuroendocrine, immune and mechanical factors contributing to the development of bronchospasm during gestation have been identified. They also cause exacerbation of the disease and aggravation of its symptoms in pregnant women with bronchial asthma:
- Increased secretion of endogenous bronchoconstrictors. The maternal part of the placenta and uterine tissues synthesize prostaglandin F2a, which stimulates the contraction of smooth muscles. Its concentration increases towards the end of gestation, ensuring the timely onset of labor. The substance also provokes respiratory obstruction due to spasm of smooth muscle fibers of the bronchi.
- An increase in the concentration of immunoglobulin E. A high level of IgE is an important link in the pathogenesis of an atopic reaction to the action of sensitizing factors. Immune restructuring in response to constant exposure to fetal antigens leads to an increase in the content of this immunoglobulin in the blood of a pregnant woman and increases the likelihood of developing bronchospasm and asthma.
- An increase in the number of α-adrenergic receptors. Hormonal shifts that occur towards the end of pregnancy are aimed at ensuring adequate labor activity. Stimulation of α-adrenoreceptors is accompanied by an increase in the contractile activity of the myometrium. The number of such receptors also increases in the bronchi, which facilitates and accelerates the occurrence of bronchospasm.
- Decreased sensitivity to cortisol. Glucocorticoids have a complex anti-asthmatic effect, affecting various links in the pathogenesis of the disease. During pregnancy, due to competition with other hormones, the pulmonary receptors become less sensitive to cortisol. As a result, the likelihood of bronchial spasm increases.
- Changing the mechanics of breathing. The stimulating effect of progesterone promotes hyperventilation and an increase in the partial pressure of carbon dioxide in the first trimester. The pressure of the growing uterus in the II-III trimesters and the increased resistance of the vessels of the small circulatory circle potentiate the appearance of shortness of breath. In such conditions, bronchospasm develops more easily.
An additional factor that increases the likelihood of asthma during pregnancy is the swelling of the mucous membranes caused by progesterone, including those lining the respiratory tract. In addition, due to the relaxation of the smooth muscles of the esophageal-gastric sphincter, gastroesophageal reflux is more often formed in pregnant women, which serves as a trigger for the development of bronchospasm. An exacerbation of the disease in a patient with manifestations of bronchial asthma may also occur if supportive treatment with glucocorticoid drugs is refused due to fear of harming the child.
The key link in the development of asthma during pregnancy is an increase in the reactivity of the bronchial tree caused by specific changes in the autonomic nervous system, inhibition of cyclic nucleotides (cAMP), degranulation of mast cells, the influence of histamine, leukotrienes, cytokines, chemokines, and other inflammatory mediators. The action of trigger allergens triggers reversible obstruction of the bronchi with increased airway resistance, overstretching of the alveolar tissue, and a mismatch between lung ventilation and perfusion. The final stage of respiratory failure is hypoxemia, hypoxia, metabolic disorders.
In the management of pregnant women suffering from bronchial asthma, a clinical systematization of the forms of the disease is used, taking into account the severity. The classification criteria for this approach are the frequency of suffocation attacks, their duration, and changes in external respiration indicators. There are the following variants of bronchial asthma during pregnancy:
- Episodic (intermittent). Attacks of suffocation are observed no more than once a week, at night they disturb the patient no more than 2 times a month. Periods of exacerbations last from several hours to several days. Outside of exacerbations, the functions of external respiration are not impaired.
- Light persistent. Characteristic symptoms occur several times during the week, but no more than once a day. With exacerbations, it is possible to disrupt sleep and habitual activity. The peak exhalation rate and its second volume during forced breathing change by 20-30% during the day.
- Persistent moderate severity. There are daily seizures. Suffocation at night develops more often than once a week. Physical activity and sleep have been changed. A 20-40% decrease in the peak exhalation rate and its second volume is characteristic when forcing with a daily variability of more than 30%.
- Severe persistent. A pregnant woman is worried about daily attacks with frequent exacerbations and the appearance at night. There are limits to physical activity. The basic indicators for assessing the functions of external respiration are reduced by more than 40%, and their daily fluctuations exceed 30%.
The clinical picture of the disease is represented by attacks of suffocation with short inhalation and long labored exhalation. In some pregnant women, the classic symptoms are preceded by an aura — nasal congestion, sneezing, coughing, the appearance of a strongly itchy urticaria rash on the skin. To facilitate breathing, a woman takes a characteristic orthopnea pose: she sits down or stands, leaning forward and lifting her shoulders. During an attack, intermittent speech is noted, an unproductive cough occurs with the discharge of a small amount of vitreous sputum, whistling wheezes are heard remotely, palpitations increase, cyanosis of the skin and visible mucous membranes is observed.
Breathing usually involves auxiliary muscles — the shoulder girdle, abdominal press. The intercostal spaces expand and retract, and the thorax acquires a cylindrical shape. When inhaling, the wings of the nose inflate. Suffocation is provoked by the action of a certain aeroallergen, a non-specific irritant (tobacco smoke, gases, harsh perfumes), physical exertion. Periodically, symptoms develop at night, disrupting sleep. With a prolonged course, pain may appear in the lower parts of the chest, associated with an overstrain of the diaphragm. The attack ends spontaneously or after the use of bronchodilators. There are usually no clinical manifestations in the intercrime period.
In the absence of proper medical control, a pregnant woman with signs of bronchial asthma develops respiratory insufficiency, arterial hypoxemia, and peripheral microcirculation is disturbed. As a result, 37% of patients have early toxicosis, 43% have gestosis, 26% have a threat of termination of pregnancy, and 14.2% have premature birth. The occurrence of hypoxia at the time when the laying of the main organs and systems of the child occurs leads to the formation of congenital malformations. According to research results, heart defects, disorders of the gastrointestinal tract, spine, and nervous system are observed in almost 13% of children carried out by women with exacerbations and attacks of suffocation in the 1st trimester.
Immune complexes circulating in the blood damage the endothelium of the uteroplacental vessels, which leads to fetoplacental insufficiency in 29% of pregnancy cases with BP. Fetal development delay is found in 27% of patients, hypotrophy — in 28%, hypoxia and asphyxia of newborns — in 33%. Every third child born to a woman with a bronchial asthma clinic is underweight. This indicator is even higher in the steroid-dependent form of the disease. Constant interaction with the mother’s antigens sensitizes the child to allergens. In the future, 45-58% of children have an increased risk of developing allergic diseases, more often suffer from acute respiratory infections, bronchitis, pneumonia.
The appearance of recurrent attacks of suffocation and sudden unproductive cough in a pregnant woman is a sufficient reason for a comprehensive examination that allows you to confirm or refute the diagnosis of bronchial asthma. In the gestational period, there are certain restrictions on the conduct of diagnostic tests. Due to the possible generalization of an allergic reaction, pregnant women are not prescribed provocative and scarification tests with possible allergens, provocative inhalations of histamine, methacholine, acetylcholine and other mediators. The most informative for the diagnosis of bronchial asthma during pregnancy are:
- Percussion and auscultation of the lungs. During an attack, a box sound is noted above the pulmonary fields. The lower borders of the lungs are shifted downwards, their excursion is practically not determined. Weakened breathing with scattered dry wheezes is heard. After coughing, mainly in the posterior parts of the lungs, wheezing wheezes increase, which in some patients may persist between attacks.
- Markers of allergic reactions. Bronchial asthma is characterized by increased levels of histamine, immunoglobulin E, and eosinophilic cationic protein (ECP). The content of histamine and IgE is usually increased both during exacerbation and between asthmatic attacks. The increase in ECP concentration indicates a specific immune response of eosinophils to the allergen + immunoglobulin E complex.
- Spirography and peak flowmetry. Spirographic examination allows, based on data on the second volume of forced exhalation (OVF1), to confirm functional disorders of external respiration of an obstructive or mixed type. During peak flowmetry, latent bronchospasm is detected, the degree of its severity and the daily variability of the peak exhalation rate (PSV) are determined.
Additional diagnostic criteria of asthma during pregnancy are an increase in the content of eosinophils in the general blood test, the detection of eosinophil cells, Charcot-Leiden crystals and Kurschmann spirals in sputum analysis, the presence of sinus tachycardia and signs of overload of the right atrium and ventricle on the ECG. Differential diagnosis is carried out with chronic obstructive pulmonary diseases, cystic fibrosis, tracheobronchial dyskinesia, constrictive bronchiolitis, fibrosing and allergic alveolitis, tumors of the bronchi and lungs, occupational diseases of the respiratory organs, pathology of the cardiovascular system with heart failure. According to the indications, the patient is consulted by a pulmonologist, an allergist.
When managing patients with BP, it is important to ensure high-quality monitoring of the condition of the pregnant woman and fetus and to maintain respiratory function at a normal level. With a stable course of the disease, a woman is examined three times during pregnancy by a pulmonologist — at 18-20, 28-30 weeks of gestation and before childbirth. The function of external respiration is monitored using peak flowmetry. Taking into account the high risk of fetoplacental insufficiency, fetometry and dopplerography of placental blood flow are regularly performed. When choosing a pharmacotherapy regimen, the severity of bronchial asthma is taken into account:
- In the intermittent form of BA, the basic drug is not prescribed. Before possible contact with the allergen, when the first signs of bronchospasm appear and at the time of the attack, inhaled short-acting bronchodilators from the group of β2-agonists are used.
- In persistent forms of asthma: basic therapy with inhaled glucocorticoids of category B is recommended, which, depending on the severity of asthma, are combined with antileukotrienes, short- or long-acting beta-agonists. The attack is stopped with the help of inhalation bronchodilators.
The use of systemic glucocorticosteroids, which increase the risk of hyperglycemia, gestational diabetes, eclampsia, preeclampsia, and the birth of a child with low weight, is justified only with insufficient effectiveness of basic pharmacotherapy. Triamcinolone, dexamethasone, depot forms are not shown. Prednisone analogues are preferred. In case of exacerbation, it is important to prevent or reduce possible fetal hypoxia. To do this, inhalations with quaternary derivatives of atropine are additionally used, oxygen to maintain saturation, and in extreme cases provide artificial ventilation of the lungs.
Although with a calm course of asthma during pregnancy, delivery by natural childbirth is recommended, in 28% of cases, in the presence of obstetric indications, a caesarean section is performed. After the onset of labor, the patient continues taking basic medications in the same dosages as during gestation. If necessary, oxytocin is prescribed to stimulate uterine contractions. The use of prostaglandins in such cases can provoke bronchospasm. During breastfeeding, it is necessary to take basic anti-asthmatic drugs in doses that correspond to the clinical form of the disease.
Prognosis and prevention
Adequate therapy of asthma during pregnancy makes it possible to completely eliminate the danger to the fetus and minimize threats to the mother. Perinatal prognoses with controlled treatment do not differ from those for children carried out by healthy women. For preventive purposes, patients at risk, prone to allergic reactions or suffering from atopic diseases, are recommended to give up smoking, limit contact with household, industrial, food, plant, animal exoallergens. Pregnant women with BA to reduce the frequency of exacerbations are shown physical therapy, therapeutic massage, special complexes of breathing exercises, speleotherapy.