INTRODUCTION — The clinical features, diagnosis, and management of respiratory infection are generally similar in pregnant and nonpregnant patients. However, some additional factors need to be considered in pregnancy, including changes in maternal susceptibility to infection, changes in maternal physiology, and the fetal effects of the infection and its treatment.

This topic will discuss issues specific to respiratory infections in the setting of pregnancy. Clinical manifestations, diagnosis, and management of respiratory infections in the general population are reviewed separately (refer to individual topic reviews on the common cold, influenza, sinusitis, pneumonia, etc).

BASIC PRINCIPLES — Awareness of pregnancy-associated changes in respiratory physiology is important to the management of respiratory disease in pregnancy (figure 1 and figure 2). Such changes allow the pregnant patient to meet the respiratory and metabolic needs of the fetus and are discussed in detail elsewhere. (See "Maternal adaptations to pregnancy: Dyspnea and other physiologic respiratory changes", section on 'Physiologic cardiopulmonary changes in pregnancy'.)

Important points to consider when evaluating pregnant patients with respiratory illness include:

●Although dyspnea is common in pregnant people due to the physiologic increase in tidal volume during pregnancy, tachypnea is abnormal as the respiratory rate remains essentially unchanged in normal pregnancies. Because spirometry remains unchanged, abnormal spirometry results should not be attributed to pregnancy and should be a signal to assess for underlying respiratory disease. (See "Maternal adaptations to pregnancy: Dyspnea and other physiologic respiratory changes", section on 'Physiologic cardiopulmonary changes in pregnancy'.)

●Pregnancy is a state of mild respiratory alkalosis related to alveolar hyperventilation. Normal third trimester arterial blood gas levels are approximately pH 7.39 to 7.45, pCO₂ 25 to 33 mmHg, pO₂ 92 to 107 mmHg, and bicarbonate 16 to 22 mEq/L. (See "Normal reference ranges for laboratory values in pregnancy".)

●Pregnant people have less buffering capacity to an acidotic insult, a 10 to 25 percent decrease in functional residual capacity (FRC), and a 20 percent increase in oxygen consumption. As a result, an apneic pregnant patient will develop hypoxia and acidosis more quickly than a nonpregnant adult. (See "Maternal adaptations to pregnancy: Dyspnea and other physiologic respiratory changes", section on 'Physiologic cardiopulmonary changes in pregnancy'.)

●Pregnant patients are prone to acute pulmonary edema related to preexisting medical conditions, pregnancy complications (eg, preeclampsia/eclampsia, peripartum cardiomyopathy, multiple gestation, amniotic fluid embolism, pyelonephritis), drugs used in managing patients with preterm labor (eg, beta-adrenergic tocolytic agents, magnesium sulfate, corticosteroids), and iatrogenic intravenous volume overload [1]. Physiologic changes related to pregnancy are also a contributing factor.

●Pregnant people are prone to aspiration pneumonia because of decreased lower esophageal sphincter tone and increased intraabdominal pressure associated with the gravid state. The risk is highest during labor and delivery due to the effects of sedation, analgesia/anesthesia, and recumbency. (See "Acute respiratory failure during pregnancy and the peripartum period", section on 'Aspiration' and "Aspiration pneumonia in adults".)

●Theoretically, pregnancy-related alterations in cell mediated immunity may increase the risk and severity of infection [2]. (See "Immunology of the maternal-fetal interface".)

●Maternal mortality and stillbirth have been reported among pregnant patients with severe respiratory infections caused by coronavirus spectrum infections (severe acute respiratory syndrome [SARS], Middle East respiratory syndrome [MERS], COVID-19), influenza A virus subtype H1N1, and other infections causing pneumonia [3-7].

●Most acute respiratory tract infections, which include acute uncomplicated bronchitis, pharyngitis, rhinosinusitis, and the common cold, are caused by viruses and do not warrant antibiotic therapy. The use of unwarranted antibiotic therapy in such cases is an important contributor to antibiotic resistance, medication-related adverse events, and unnecessary cost [8]. Antibiotic stewardship plays an important role in controlling rates of Clostridioides difficile infection, which is associated with significant maternal morbidity and mortality [9]. (See "Clostridioides difficile infection in adults: Clinical manifestations and diagnosis" and "Clostridioides difficile infection in adults: Treatment and prevention" and "Clostridioides difficile infection in adults: Epidemiology, microbiology, and pathophysiology".)

In a prospective study, approximately one-third of acute respiratory tract infections in pregnant patients were associated with symptoms consistent with acute lower respiratory tract illness (difficulty breathing or shortness of breath, wheezing, or cyanosis) [10]. Human rhinovirus, respiratory syncytial virus, human coronaviruses, and influenza accounted for almost all of the virus-positive cases.

GENERAL APPROACH — The general approach to caring for pregnant patients with respiratory illness is a two stage process:

●Determine the appropriate clinical evaluation and treatment. The initial approach to evaluating a pregnant patient with respiratory illness is similar to that of a nonpregnant patient and includes history, physical examination, and differential diagnosis.

Tachycardia, tachypnea, and decreased oxygen saturation are not normal physiologic changes in pregnancy; thus, the presence of these, or other abnormal lung findings such as crackles (rales) or other signs of consolidation, is indicative of an underlying disease process that requires further investigation.

●Determine whether implementing this diagnostic and therapeutic plan carries any additional risks for the pregnant patient or fetus. These additional risks may be related to increased maternal susceptibility to severe disease or complications (eg, influenza) and/or to potential fetal risks related to the disease, its evaluation, or its treatment (eg, tetracycline may stain developing teeth). If so, are there alternative diagnostic tests or treatments that reduce or eliminate these risks? What are the risks in not implementing this plan in the pregnant patient?

SELECTED DISORDERS AND TREATMENT

The common cold — As in nonpregnant patients, symptoms related to the common cold are usually mild and self-limited and generally neither require nor respond well to intervention. However, many pregnant people with the common cold will seek advice and symptomatic therapy from their clinician. (See "The common cold in adults: Diagnosis and clinical features" and "The common cold in adults: Treatment and prevention".)

Treatment — Patients with the common cold can be reassured that their symptoms will generally resolve within 10 days, although the cough may linger longer. Drug therapy may relieve some symptoms; however, treatment does not shorten the duration of symptoms, and the risks of drug therapy for the common cold in pregnancy have not been studied in randomized trials. If the patient still seeks symptomatic relief after being informed of the self-limited nature of the illness, the limited efficacy of all available treatments, and the absence of high-quality evidence of safety, the patient should be steered toward those agents with the most evidence of lack of fetal harm. Data about the safety and efficacy of several drugs used to treat the common cold are provided in the tables (table 1A-D).

In general, use of heated humidified air for congestion and acetaminophen for sore throat and headache offer the best balance of safety and efficacy.

●A large epidemiologic study (National Birth Defects Prevention Study, 1997 to 2011) described an association between maternal report of cold or flu with fever in early pregnancy and congenital anomalies, but no association in similar individuals without fever [11]. Although fever may be a marker for more severe cold/flu or other differences between the groups, the possibility of a causal association between fever and congenital anomalies cannot be excluded. In another report, among patients reporting a first-trimester infection and fever, use of acetaminophen was associated with a reduction of some congenital abnormalities that have been related to maternal hyperthermia [12]. Therefore, if fever is present, it is reasonable to suggest use of acetaminophen to relieve discomfort from fever, and it may have additional benefits. The overall safety of acetaminophen is reviewed separately. (See "Prenatal care: Patient education, health promotion, and safety of commonly used drugs", section on 'Acetaminophen'.)

For patients with more severe symptoms and who desire drug therapy (table 1A-D):

●Ipratropium bromide nasal spray is an option; animal studies have not observed teratogenic effects, but there are no human data. The 0.06 percent ipratropium bromide nasal spray is typically administered as two 42 mcg sprays to each nostril three to four times a day. Intranasal cromolyn sodium is another option. Inhaled cromolyn preparations may cause transient bronchospasm, throat irritation, and cough; caution is warranted in asthmatics.

●Cough can be suppressed with dextromethorphan or guaifenesin.

Antibiotics are not indicated for treatment of the common cold, except in the small subset of patients (less than 2 percent) with evidence of secondary bacterial sinus infection [13] (see 'Sinusitis' below). The pregnant state does not change the usual standards for administering or withholding antibiotics. (See "The common cold in adults: Treatment and prevention", section on 'Antibiotic therapy'.)

Bronchitis — Acute bronchitis is characterized by self-limited inflammation of the bronchi, which is clinically expressed as cough, usually with sputum production. Acute bronchitis cannot be distinguished from the common cold in the first few days of illness, but acute bronchitis should be considered when cough persists. In most cases, the cough persists for one to three weeks. The absence of abnormalities on chest radiography distinguishes acute bronchitis from pneumonitis. Febrile patients are more likely to have influenza or pneumonia than bronchitis or the common cold. A chest radiograph can be done safely in pregnancy and should be performed when there are findings suggestive of pneumonia, such as tachypnea, tachycardia, hypoxia, fever, crackles, or evidence of consolidation on examination. (See "Acute bronchitis in adults", section on 'Clinical features' and "Acute bronchitis in adults", section on 'Diagnosis' and "Diagnostic imaging in pregnant and nursing patients".)

Bronchitis is caused by a virus in approximately 90 percent of cases. Etiologic agents include influenza A and B, parainfluenza virus 3, coronavirus, adenovirus, metapneumovirus, rhinovirus, and respiratory syncytial virus. Purulent sputum is reported in 50 percent of patients with acute bronchitis [14]. This usually represents sloughing of cells from the tracheobronchial epithelium, along with inflammatory cells. Purulence and sputum discoloration do not signify bacterial infection. Occasional patients have acute bronchitis caused by M. pneumoniae, C. pneumoniae or, increasingly, Bordetella pertussis. These etiologies should be suspected in patients with prolonged cough, even in the absence of the classic post-tussive emesis, cough paroxysms, or inspiratory whoop seen in children with pertussis. In general, testing or empiric treatment for these pathogens is not recommended unless there is evidence of a local outbreak [15]. (See "Mycoplasma pneumoniae infection in adults" and "Pneumonia caused by Chlamydia pneumoniae in adults" and "Pertussis infection in adolescents and adults: Clinical manifestations and diagnosis" and "Respiratory syncytial virus infection: Treatment".)

Treatment — Symptomatic treatment is the same as for the common cold (see 'The common cold' above). Antibiotic therapy of viral bronchitis is not beneficial [16] and rarely indicated. (See "Acute bronchitis in adults", section on 'Antimicrobial therapy'.)

Some patients experience symptomatic relief from cough with use of a steam humidifier. Since cough suppressants are not generally useful for treatment of the cough associated with bronchitis, pregnant people should be discouraged from using such agents. Supportive care and reassurance are the preferred treatment measures.

Sinusitis — Pregnant people with the common cold are at increased risk of developing rhinosinusitis and Eustachian tube dysfunction, which has been attributed to congestion from hormonal effects on the nasal mucosa [17]. Almost all rhinosinusitis is due to viruses; only a small fraction of cases develop secondary bacterial infection. Uncomplicated acute viral rhinosinusitis typically resolves in 7 to 10 days.

Many pregnant patients with documented rhinosinusitis do not have classic historical and physical findings, which include nasal congestion, purulent nasal discharge, maxillary tooth discomfort, hyposmia, and facial pain or pressure that is worse when bending forward [18]. Despite the increased frequency of atypical presentations in pregnant patients, there are no specific recommendations for distinguishing the common cold from bacterial rhinosinusitis in pregnancy. Therefore, we use the following criteria to diagnose acute bacterial rhinosinusitis, which are supported by several guidelines [8,19-21]:

●Persistent symptoms or signs of acute rhinosinusitis lasting 10 or more days without evidence of clinical improvement. (See "Acute sinusitis and rhinosinusitis in adults: Clinical manifestations and diagnosis", section on 'Symptoms'.)

●Onset of severe symptoms or signs of high fever (>39°C or 102°F) and purulent nasal discharge or facial pain for at least three to four consecutive days at the beginning of illness.

●Onset with worsening ("double worsening") symptoms or signs (new onset fever, headache, nasal discharge) following a typical viral upper respiratory infection that lasted five to six days and were initially improving.

Radiographic imaging is not indicated for uncomplicated sinusitis. When indicated for the evaluation of refractory sinusitis symptoms, sinus imaging (with appropriate pelvic shielding) should be performed during pregnancy. As an example, imaging studies are indicated in patients with clinical signs or symptoms of complicated acute bacterial rhinosinusitis, including diminished visual acuity, diplopia, periorbital edema, severe headache, or altered mental status. If imaging is necessary, sinus radiographs are usually obtained initially in order to avoid the higher doses of radiation associated with computed tomography. Computed tomography and magnetic resonance imaging are usually reserved for complicated cases. Ultrasonography is not a good substitute because of variable performance [22]. (See "Diagnostic imaging in pregnant and nursing patients" and "Acute sinusitis and rhinosinusitis in adults: Clinical manifestations and diagnosis" and "Chronic rhinosinusitis: Clinical manifestations, pathophysiology, and diagnosis".)

Treatment — We suggest observation (watchful waiting) with symptomatic management for immunocompetent pregnant patients with acute bacterial rhinosinusitis who have good follow-up (assurance that antibiotic therapy can be started if the patient does not improve or worsens). This approach is similar to that from a multidisciplinary expert panel [19] and differs from the 2012 Infectious Diseases Society of America guidelines, which prefer prompt initiation of antibiotics when the clinical diagnosis of acute bacterial sinusitis has been established based on one of the criteria listed above [20]. However, we are more likely to initiate antibiotic therapy for pregnant patients with fever (eg, >102°F [38.9°C]) associated with severe symptoms.

The approach to treatment is the same as in nonpregnant females, except doxycycline and fluoroquinolones are avoided (see "Uncomplicated acute sinusitis and rhinosinusitis in adults: Treatment"). Fluoroquinolones and tetracyclines are generally avoided in pregnancy because of potential effects on fetal cartilage, bones, and teeth. Although doxycycline appears to be safer than older tetracyclines, data are low quality and insufficient to say that there is no risk. If there is a safer, effective drug that can be used as an alternative, it should be used. But if there is no good alternative (eg, Rocky Mountain spotted fever), doxycycline should be used rather than tetracycline. (See "Prenatal care: Patient education, health promotion, and safety of commonly used drugs", section on 'Antibiotics'.)

Acceptable adjunct treatments in pregnancy include saline nasal spray or buffered saline nasal irrigation, acetaminophen, and steroid nasal sprays (eg, beclomethasone or budesonide) for patients who cannot tolerate ongoing nasal congestion and pain while awaiting resolution of the infection with antibiotic therapy. Nasal steroids provide only small symptomatic benefits in patients with sinusitis and are likely to be most beneficial for those with underlying allergic rhinitis. Antihistamines have no role in the symptomatic relief of acute bacterial sinusitis in nonatopic patients [19]. There is no convincing evidence of benefit from use of decongestants or guaifenesin. (See "Chronic rhinosinusitis: Management", section on 'Intranasal saline' and "Recognition and management of allergic disease during pregnancy", section on 'Glucocorticoid nasal sprays'.)

Monitoring and follow-up of patients with uncomplicated bacterial rhinosinusitis are reviewed in detail separately. (See "Uncomplicated acute sinusitis and rhinosinusitis in adults: Treatment".)

Influenza — The influenza pandemics of 1918, 1957, and 2009 were associated with increased morbidity and mortality in pregnant people. Because of the potential seriousness of influenza infection in pregnancy, and the safety of immunization, universal vaccination of pregnant patients across gestation is recommended by the American College of Obstetricians and Gynecologists (ACOG) and the United States Centers for Disease Control and Prevention (CDC). (See "Immunizations during pregnancy", section on 'Inactivated influenza vaccine'.)

Treatment — For pregnant patients and those up to two weeks postpartum with suspected acute influenza, prompt empiric treatment with appropriate influenza antiviral medications is recommended due to the potential adverse effects of influenza on pregnancy. The diagnosis, clinical course, acute treatment, and prevention of influenza in pregnancy are reviewed in detail separately. (See "Seasonal influenza and pregnancy".)

Community-acquired pneumonia — The incidence of pneumonia in pregnancy appears to be similar to that in nonpregnant patients, with reported rates varying from 0.2 to 8.5 per 1000 deliveries [16]. The wide range is likely related to differences in the patient populations studied, as well as the availability and state of medical care at the time of the study.

Pneumonia accounted for 30 percent of concurrent infections diagnosed in pregnant patients with severe sepsis in the United States (1998 to 2008 [23]). It is associated with significant maternal and fetal morbidities, but death of pregnant patients is rare [2,24-27]. Risk factors for pneumonia in pregnancy include anemia, asthma, smoking, illicit drug use, and immunosuppressive illness (eg, HIV/AIDS) or immunosuppressive therapy [28].

The classic symptoms of pneumonia are sudden onset of rigors followed by fever, pleuritic chest pain, shortness of breath, and cough productive of purulent sputum; however, most patients do not present with classic symptoms. The clinical manifestations of pneumonia and the diagnostic evaluation of patients with suspected pneumonia are similar to those in nonpregnant individuals. (See "Overview of community-acquired pneumonia in adults", section on 'Clinical presentation' and "Overview of community-acquired pneumonia in adults", section on 'Diagnosis'.)

A chest radiograph is required to diagnose pneumonia and should never be withheld from a pregnant patient in whom this diagnosis is suspected. The indications for obtaining a chest radiograph (posteroanterior and lateral views) in pregnancy are the same as in nonpregnant patients and include shortness of breath and/or cough in association with fever, tachycardia, tachypnea, decreased oxygen saturation, or rales or signs of consolidation on lung examination. The estimated fetal absorption for the chest radiographs is <0.01 mGy (<0.001 rad); this dose is well below doses that have been associated with any short- or long-term adverse effects [29]. The abdomen should be shielded. (See "Diagnostic imaging in pregnant and nursing patients".)

Lung ultrasound is emerging as a valuable diagnostic tool, particularly in the emergency department and intensive care unit (ICU). Currently, there are no recommendations for use of ultrasound instead of a diagnostic chest radiograph in nonpregnant patients; therefore, while it may be an additional tool to consider in specific circumstances where there is local expertise, more research is needed about its diagnostic use in pregnancy. The chest radiograph currently remains the gold standard for diagnosis of pneumonia in pregnancy [30-33].

Pregnant patients with pneumonia are prone to preterm labor and delivery [34], as well as pulmonary edema [35]. While there does not appear to be an increase in perinatal mortality, the frequency of low birth weight infants born to mothers with pneumonia is higher than among controls without pneumonia [36]. Pregnant people may be predisposed to a severe pneumonia course because of physiologic changes of pregnancy, including elevation of the diaphragm by up to 4 cm, decrease in functional residual capacity, increase in oxygen consumption, and increase in lung water. These changes make the pregnant patient less able to tolerate even brief periods of hypoxia. In addition, tachypnea can cause respiratory alkalosis, which reduces uterine blood flow. Given these factors, these authors have a low threshold for admitting pregnant patients with pneumonia to the hospital, where they can receive intravenous hydration, supplemental oxygen, and close maternal-fetal monitoring until there is clinical improvement.

Pneumonia may result in respiratory failure. Early anticipation of possible intubation allows for better preparation and execution, should it be needed. Management of respiratory failure is discussed separately. (See "Airway management for the pregnant patient" and "Acute respiratory failure during pregnancy and the peripartum period".)

Treatment

●Indications for hospitalization – Severity of illness is the primary factor for determining the site of treatment. Pregnant patients with community-acquired pneumonia who have very mild disease (eg, stable normal heart and respiratory rates, oxygen saturation ≥95 percent during ambulation, absence of serious comorbidities) and who can maintain oral intake and adhere to medical therapy can be treated as outpatients.

Most other patients can be managed initially on the general ward or labor and delivery unit; intensive care unit admission is needed for those requiring mechanical ventilation or with septic shock. The severe spectrum of illness is suggested by respiratory rate >30 breaths/minute, PaO₂/FiO₂ ratio <250, multilobar infiltrates, confusion/disorientation, uremia (blood urea nitrogen level >20 mg/dL), leukopenia (white blood cell count <4000 cells/mm³), thrombocytopenia (platelet count <100,000 cells/mm³), hypothermia (core temperature <36°C), hypotension requiring aggressive fluid resuscitation, hypoglycemia (in nondiabetic patients), hyponatremia, or unexplained metabolic acidosis or elevated lactate level. (See "Community-acquired pneumonia in adults: Assessing severity and determining the appropriate site of care".)

The decision to admit a pregnant patient with features of severe illness to the intensive care unit is complex, as most hospitals do not have an obstetric ICU. Discussions regarding the best place in the hospital to manage the sick pregnant patient with pneumonia need to include the input of the obstetrician and intensivist.

●Treatment

•The table summarizes the major points in treatment of pneumonia (table 2).

•Maternal oxygen saturation (SaO₂) should be maintained at ≥95 percent during pregnancy, which is ideal for maintaining adequate fetal oxygenation. If SaO₂ falls below 95 percent, an arterial blood gas is obtained to measure PaO₂. Maternal PaO₂ ≥70 mmHg is desirable to maintain a favorable oxygen diffusion gradient from the maternal to the fetal side of the placenta.

•Antibiotic therapy is targeted to cover the infecting organisms typically associated with community-acquired pneumonia in nonpregnant patients. Pathogens include Streptococcus pneumoniae, Haemophilus influenzae, mycoplasma, chlamydia, viruses, legionella, Staphylococcus aureus, and gram negative bacilli [37]. Gram negative bacilli tend to cause pneumonia in patients with underlying morbidities, and therefore, these organisms are uncommon in young, otherwise healthy, pregnant people. Influenza should be considered when influenza is active in the community. In addition, similar to pneumonia in nonpregnant individuals, other viruses should also be considered.

For pregnant patients with community-acquired pneumonia who have mild disease for which outpatient therapy is indicated, we suggest a combination of amoxicillin or amoxicillin/clavulanate plus azithromycin. For those with a type-I allergy to beta-lactams, clindamycin can be substituted for the beta-lactam.

For pregnant patients who require hospitalization and with no features of severe disease, we suggest combination therapy with an antipneumococcal beta-lactam (ceftriaxone, cefotaxime, ampicillin-sulbactam) plus azithromycin, given the >25 percent rate of macrolide resistance in all regions of the United States and in certain other countries. Those with past allergic reactions to cephalosporins can be treated with clindamycin plus aztreonam, unless they have severe pneumonia, in which case, we recommend vancomycin (for coverage for MRSA and drug-resistant S. pneumoniae) plus azithromycin plus aztreonam.

Some antibiotics to be avoided in pregnancy include tetracyclines, clarithromycin, and the fluoroquinolones (table 3). Although azithromycin has a good safety profile, clarithromycin has produced adverse pregnancy outcomes in animal studies at low-order multiples of human doses; human experience is very limited and has not suggested an increase in congenital anomalies in exposed pregnancies [38,39], but an increased risk of miscarriage has been reported, possibly related to the underlying disease [39,40]. The fluoroquinolones are avoided during pregnancy because of concerns about fetal arthropathy and malformations based on animal studies. However, safe use in pregnancy has been reported, suggesting that they may be used if alternatives are less safe or effective [41]. As discussed above, although doxycycline appears to be safer than older tetracyclines, data are low quality and insufficient to say that there is no risk. If there is a safer, effective drug that can be used as an alternative, it should be used. But if there is no good alternative (eg, Rocky Mountain spotted fever), doxycycline should be used rather than tetracycline.

Three antimicrobials for treatment of community-acquired pneumonia became available since 2017: lefamulin (a pleuromutilin drug), omadacycline (a tetracycline derivative), and delafloxacin (a fluoroquinolone). All should be avoided in pregnancy due to some nonreassuring animal data, lack of human safety data, and the potential for adverse pregnancy outcomes. (See "Treatment of community-acquired pneumonia in adults in the outpatient setting" and "Treatment of community-acquired pneumonia in adults who require hospitalization".)

•Varicella-zoster pneumonia is especially severe in pregnant patients; fulminate pneumonia develops in approximately 10 to 20 percent of gravidas infected with chickenpox. Maternal mortality is as high as 40 percent [42]. Treatment with acyclovir or valacyclovir is warranted in pregnant patients to reduce the risk of respiratory failure and maternal death. The maternal complications along with the potentially serious fetal/neonatal consequences of varicella underline the importance of establishing the immune status of females with respect to varicella and vaccinating those who are not immune prior to a planned pregnancy. The clinical features and treatment of varicella pneumonia in pregnancy are reviewed elsewhere. (See "Varicella-zoster virus infection in pregnancy".)

Hospital-acquired and aspiration pneumonia — The causes of hospital-acquired pneumonia in pregnancy include the same causes as in the nonpregnant patient, but certain caveats exist. Pregnant people are prone to aspiration during labor and delivery, and this must always be a major consideration. Infection with Gram negative rods, including Pseudomonas, also becomes more likely in this setting.

Prevention and treatment are discussed separately. (See "Risk factors and prevention of hospital-acquired and ventilator-associated pneumonia in adults" and "Aspiration pneumonia in adults".)

Virus-induced wheezing and asthma — Viral respiratory infections, particularly with respiratory syncytial virus and human rhinovirus, are the most common causes of wheezing in infants and young children and are common triggers of asthma exacerbations in up to 50 percent of adult patients and up to 85 percent of pediatric patients with preexisting asthma (see "Role of viruses in wheezing and asthma: An overview"). The evaluation and differential diagnosis of wheezing in adults are reviewed separately. (See "Evaluation of wheezing illnesses other than asthma in adults".)

Inhaled beta agonists, such as albuterol, can be used safely in pregnancy to treat wheezing, as in nonpregnant patients. Treatment is reviewed in more detail separately. (See "Management of asthma during pregnancy", section on 'Acute exacerbations' and "An overview of asthma management".)

COVID-19 — (See "COVID-19: Overview of pregnancy issues".)

POSTPARTUM ISSUES

Infection control — Patients who give birth while being treated for a respiratory infection rarely need to be separated from their newborns, but they should use good hand hygiene and wear a face mask to minimize transmission of the illness. Active tuberculosis is an exception and requires at least temporary separation between mother and newborn. (See "Tuberculosis in pregnancy", section on 'Controlling transmission'.)

Recommendations about infection control of influenza-infected patients in the peripartum and postpartum settings can be found on the United States Centers for Disease Control and Prevention's (CDC) website and in a separate topic review. (See "Infection control measures for prevention of seasonal influenza".)

Mother-newborn issues related to COVID-19 are also addressed separately. (See "COVID-19: Intrapartum and postpartum issues".)

Breastfeeding — In general, breastfeeding should not be discouraged because of maternal respiratory infection. Breastfeeding is the preferred method of feeding and will likely confer some passive immunity to the newborn. Most medications used to treat respiratory illness in pregnancy are also acceptable for use in breastfeeding mothers. Medications that should be avoided in breastfeeding include the quinolones and tetracyclines [37,43]. Both the UpToDate drug database and the Drugs and Lactation Database of the United States National Library of Medicine (LactMed) provide information on drug levels in milk and possible drug effects on breastfed infants and on lactation.

Mother-newborn issues related to COVID-19 and breastfeeding are addressed separately. (See "COVID-19: Intrapartum and postpartum issues".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Respiratory disease in pregnancy".)

SUMMARY AND RECOMMENDATIONS

●General principles

•Awareness of pregnancy-associated changes in respiratory physiology is important to the management of respiratory disease in pregnancy. (See 'Basic principles' above.)

•The two major considerations when medically treating pregnant patients for respiratory infection are to first determine the appropriate clinical evaluation and treatment of a nonpregnant patient with the same presentation and then to determine whether implementing this diagnostic and therapeutic plan carries any additional risks for the pregnant patient or fetus. These additional risks may be related to increased maternal susceptibility to severe disease or complications in pregnancy (eg, influenza) and/or to potential fetal risks related to the disease (eg, congenital infection), its evaluation (eg, radiation from diagnostic imaging), or its treatment (eg, tetracycline may stain developing teeth). (See 'General approach' above.)

•Most acute respiratory tract infections, which include acute uncomplicated bronchitis, pharyngitis, rhinosinusitis, and the common cold, are caused by viruses and do not warrant antibiotic therapy. The use of unwarranted antibiotic therapy in such cases is an important contributor to antibiotic resistance, medication-related adverse events, and unnecessary cost. (See 'Sinusitis' above.)

●The common cold – We suggest heated humidified air for congestion and acetaminophen for sore throat/headache/fever. If drug therapy is elected for symptomatic relief of rhinorrhea, we suggest ipratropium bromide and cromolyn nasal spray. (See 'The common cold' above.)

●Sinusitis – The approach to treatment is the same as in nonpregnant adults, except doxycycline and levofloxacin are avoided (see "Uncomplicated acute sinusitis and rhinosinusitis in adults: Treatment"). Fluoroquinolones and tetracyclines are generally avoided in pregnancy because of potential effects on fetal cartilage, bones, and teeth. Although doxycycline appears to be safer than older tetracyclines, data are low quality and insufficient to say that there is no risk. If there is a safer, effective drug that can be used as an alternative, it should be used.

Acceptable adjunct treatments in pregnancy include saline nasal spray or buffered saline nasal irrigation, acetaminophen, and steroid nasal sprays for patients who cannot tolerate ongoing nasal congestion and pain while awaiting resolution of the infection. Nasal steroids provide only small symptomatic benefits in patients with sinusitis and are likely to be most beneficial for those with underlying allergic rhinitis. (See 'Sinusitis' above.)

●Bronchitis – We suggest use of a steam humidifier. (See 'Bronchitis' above.)

●Pneumonia

•For pregnant patients with community-acquired pneumonia who have very mild disease for which outpatient therapy is indicated, we suggest a combination of amoxicillin or amoxicillin/clavulanate plus azithromycin. For patients who have a type-I allergy to beta-lactams, clindamycin can be substituted for the beta-lactam. For patients who require hospitalization and with no features of severe disease, we suggest combination therapy with an antipneumococcal beta-lactam (ceftriaxone, cefotaxime, ampicillin-sulbactam) plus azithromycin. Patients with past allergic reactions to cephalosporins can be treated with clindamycin plus aztreonam, unless they have severe pneumonia. For patients with severe pneumonia and past reactions to cephalosporins, we suggest vancomycin plus azithromycin plus aztreonam.

Antibiotics that are generally avoided in pregnancy include tetracycline, clarithromycin, and the fluoroquinolones. Although doxycycline appears to be safer than older tetracyclines, data are insufficient to say that there is no risk. If there is a safer, effective drug that can be used as an alternative, it should be used.

Pregnant patients with pneumonia are prone to develop preterm labor and delivery, as well as pulmonary edema. They are best treated as inpatients until there is clinical improvement. (See 'Community-acquired pneumonia' above.)

•Hypoxia and acidosis are poorly tolerated by the fetus and should be aggressively avoided. Maternal pO₂ should be kept at ≥70 mmHg (or at an oxygen saturation of at least 95 percent) to maintain adequate fetal oxygenation. (See 'Community-acquired pneumonia' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Raymond Powrie, MD, who contributed to an earlier version of this topic review.