Respiratory workers play a crucial role in the well-being of pregnant asthmatics; however, more work needs to be done.
Pregnancy can be both a wonderful and frightening time in a woman’s life. Pregnant women with asthma are no exception. While asthma may pose a problem to a small percentage of pregnant women who have the condition, proper treatment and maintenance can help alleviate possible complications for both mother and baby.
It has been reported that 7% of the pregnant population is affected by asthma. Studies have found that 0.4% to 4% of pregnant asthmatic women experience complications due to asthma during pregnancy.1,2 However, the actual rate of pregnant women who experience asthma complications may be much higher for two reasons. First, a history of asthma may not always be recorded during antenatal care. Second, women receiving asthma and maternity care from different institutions may confound the reported percentage.3 Of this percentage, 20% to 43% report no difference in asthma severity during pregnancy, 14% to 69% note a reduction in asthma seriousness, and 6% to 43% observe an increase in pulmonary symptoms during pregnancy.4
Studies5 have noted that the rate of asthma experienced by pregnant women almost doubled from 1989 to 1992. Considering the increasing occurrence of childhood asthma and respiratory illness in the past 2 decades, it is not surprising to find more reported cases of younger asthmatic mothers experiencing complicated pregnancies than older asthmatic mothers.3 Some research suggests that 11% to 18% of pregnant asthmatics have at least one visit to the emergency department for acute asthma and as many as 62% who have acute asthma need to be hospitalized.6 Statistics like these attest to the conviction that improperly controlled asthma during pregnancy can lead to serious complications for both mother and baby.8
A study6 has found that exacerbations of respiratory problems during pregnancy are most likely the direct result of asthma and not due to the physiological transformations that accompany pregnancy. Some theories that attempt to explain the relationships between maternal asthma and pregnancy involve pathophysiologic mechanisms. A common underlying etiology for the irritability or hyperactivity of both uterine and bronchial smooth muscles has been identified as a possible mechanism responsible for negative outcomes for mother and child. The release of bioactive mediators, hypoxia secondary to maternal asthma, and medications used to treat asthma have also been noted as possible factors influencing the outcomes of mother and baby.1
It has been reported that severe asthma is likely to be aggravated during pregnancy. Any worsening most frequently occurs between the 24th and 36th weeks of pregnancy. However, a significant improvement in asthma symptoms during the final month of pregnancy may occur. This generality does not always apply. For instance, some women with severe asthma may experience an improvement in their asthma and some women with mild asthma may experience an exacerbation during pregnancy.7 It has been noted that any exacerbation of asthma experienced during pregnancy will remain similar in each following pregnancy.8
Complications
Many complications can result from inadequate treatment of pregnant asthmatics. In rare cases, respiratory failure and death to the mother due to asthma complications have been noted.8.9 In addition, pregnant asthmatics were found to be twice as likely to have experienced a threatened miscarriage (before 20 weeks gestation) than nonasthmatic pregnant women. A significant increased risk of spontaneous miscarriage and intrauterine fetal fatality was also found to occur.3 Other complications due to asthma can include vaginal bleeding, hyperemesis gravidarum, instrumental deliveries, and cesarean section.10 A decrease of Pao2 below 60 mm Hg throughout maternal status asthmaticus may distress the fetus. At this point, the pregnancy may be terminated by cesarean section.10
High blood pressure difficulties such as preeclampsia are also elevated among pregnant asthmatics with a twofold to threefold increased incidence when compared to nonasthmatics.7,11 Severe preeclampsia can result in seizures and be potentially fatal for both mother and baby. Chronic maternal hypertension has also been observed.11 Hypoxemia and asymmetric intrauterine growth retardation are additional complications that pregnant asthmatics may experience.10 Additional research10 has noted that pregnant asthmatics were more likely to contract both respiratory and urinary infections, with incidence of occurrence being greater in acute asthmatics than mild asthmatics; the incidence is higher in mild asthmatics than nonasthmatics. Other adverse symptoms more frequently experienced by asthmatic pregnant women than their nonasthmatic peers include placenta previa and antepartum hemorrhage.7
Complications experienced by the fetus of an improperly treated pregnant asthmatic woman can vary as much as the mother’s possible complications. Unfounded fears surrounding the possible adverse effects of asthma medications on the developing fetus have led to a tragic environment of under-treatment and poor maintenance of maternal asthma.8 Improperly maintained asthma can result in acute asthma episodes, which, in turn, can cause harm to the fetus by depleting the oxygen it receives.12 A fetus needs a steady supply of oxygen for normal growth and development.11 When a pregnant mother experiences hypoxemia, it is very important to assess the health of the baby. Electronic fetal heart monitoring of the baby and lung measurements of the mother may be called for.9
Premature birth, slow growth, development problems, stillbirth, and low birth weight are other suggested complications that may be experienced by the fetus of an improperly treated asthmatic mother.9,13 Transient tachypnea of the newborn, neonatal hyperbilirubinemia, neonatal hypoxia, and postpartum bleeding are additional complications.7 Pregnant asthmatics with severe, inadequately treated asthma have the highest risk of experiencing periods of fetal hypoxia.8 However, there are no clues that link congenital malformations of the fetus with a mother’s asthma status.11 Maternal hypocapnia, dehydration, and alkalosis are other deleterious effects of untreated or undertreated asthma. These complications are dangerous to the infant because they may unfavorably affect fetal oxygenation by restricting uteroplacental blood flow.7
Treatment
Many of the complications listed above can be reduced, if not eliminated, by good asthma treatment and maintenance. Unsubstantiated concerns regarding teratogenesis have previously led to the undertreatment of asthma during pregnancy.3 It has been recommended that an asthmatic woman should be followed closely throughout her pregnancy so that any change in her asthma symptoms can be matched with appropriate treatment.11 Obstetricians and gynecologists have an excellent opportunity to promote good asthma maintenance during antenatal care.3
Generally, asthma is considered to be under control if the mother can sleep through the night without waking due to asthma symptoms, remain active without incident of asthma symptoms, and achieve her personal best peak flow number.9 Controlling the environment by avoiding asthma triggers is the first step in avoiding asthmatic episodes. The second step involves continuing regularly scheduled medications throughout the pregnancy. A continuum of medication appears to have the best results. Prompt treatment should be used to control an asthma episode. Reliever medications that the woman has had previous success with are most commonly recommended. A continuum of medication includes increasing and decreasing the number and frequency of medications as necessary to control or maintain control.12
Medication
While it has been reported that 12% to 31% of asthmatic women take asthma medications during pregnancy, studies on asthma and medications administered during pregnancy have produced conflicting results.13 Although no asthma medication has been found to be completely “safe,” there are quite a few that are considered to be safe for use by pregnant asthmatics as their “risks” are considered to be less detrimental than the complications associated with untreated asthma.9,11 Rita Kay Cydulka, MD, attending physician at MetroHealth Center, and associate professor at Case Western Reserve University School of Medicine, Cleveland, agrees, “The greatest problem faced by pregnant asthmatics is receiving inadequate treatment for asthma. Some physicians are reluctant to prescribe inhaled corticosteroids, etc to pregnant asthmatics because of concerns with the fetus. However, data indicate that the better the mother’s asthma is controlled, the better off the fetus is.”
On the basis of animal studies, the FDA has attempted to provide a classification system as a guideline for physicians who are searching for the best medication for use by pregnant asthmatics. The FDA letter-based system is ranked A, B, C, D, or X with Category A being the safest drug and Category X being found unsafe and contraindicated. To date, no Category A drugs are available for use by pregnant asthmatics. Since uncontrolled asthma is more likely to be detrimental for mother and baby, a medication choice needs to be made between a new Category B drug, which has little or no human pregnancy findings, or a Category C drug, which has a history of use and encouraging human data.14
Older asthma medications are generally preferred for treatment since there is a firm knowledge base about their usage and effects during pregnancy. It has been recommended that use of asthma medication should be limited during the first trimester. The baby develops the most during the first trimester, and concern about the possibility of birth defects exists, although they are rare.9 Aspirin or other acetylsalicylic acid products should be avoided by the pregnant asthmatic as they may cause life-threatening asthmatic episodes if the mother is sensitive to this drug.12
Pharmaceuticals
Pharmaceuticals with a local, not system-wide, effect show favorable outcomes for asthma treatment during pregnancy. Cromolyn sodium, nedocromil, long-acting b2-agonist inhaled bronchodilators, salmeterol, ipratropium beclomethasone, albuterol, metaproterenol, and terbutaline are all considered to be safe pharmaceutical asthma treatments.8,13 If these medications are not effective, theophylline appears to be a safe additional treatment. But, while not significant, there have been some conflicting reports about the correlation between theophylline and preeclampsia. If the asthma is especially severe, an oral steroid, such as prednisone, may be an additional necessary treatment.11 It has been proposed that any complication resulting from prednisone treatment may be due to a dose-dependent or duration-dependent effect.7
Current pharmacological treatment has found success with prophylactic inhaled glucocorticoids. This medication is appropriate for pregnant asthmatics whose symptoms indicate a more aggressive treatment than the use of an inhaled bronchodilator once a week or less. Prophylactic inhaled glucocorticoid therapy has proven to be a suitable treatment because it is noted to be the most effective and least toxic way to control attacks. A b2-agonist bronchodilator can accompany this treatment for immediate relief of an episode.8
Previous research has concluded that asthmatic women are at a higher risk for postpartum hemorrhage than nonasthmatic women. Past findings also indicated that pregnant asthmatics taking medication were at a higher risk for postpartum hemorrhage than pregnant asthmatics not taking medication. However, the hemorrhage differences between medication and no-medication groups were not found to be significant. In contrast, Alexander et al15 noted a significant increase in postpartum hemorrhage in asthmatic women independent of medication use, concluding that the increased incidence of postpartum hemorrhage was related to alterations in coagulation associated with asthma.15
Corticosteroids
Some other possible negative consequences that may result from pharmacological treatment involve corticosteroids. It has been suggested that pregnant asthmatics treated with corticosteroids and their accompanying depression of the immune system may have a higher frequency of infection. The significant elevation of infection levels was noted to be more prominent in patients treated with systemic cortico-steroids for a prolonged period of time. A positive correlation was not found between short-term corticosteroid treatments and increased levels of infection.10
Corticosteroid treatments have also been associated with a significantly increased risk of gestational diabetes. Preterm deliveries and low birth weight have been associated with corticosteroid use. A slightly elevated risk for the infant to be born with a cleft palate is another possible effect.10
Other research15 indicates that pregnant asthmatics treated with corticosteroids have a higher incidence of pregnancy-induced hypertension. However, findings15 indicating corticosteroids as the sole mechanism responsible are not definite. Pregnancy-induced hypertension may also be the result of poorly controlled asthma. Overall, corticosteroid treatments were not found to be associated with teratogenic influences so it appears that this treatment may be appropriate to use for pregnant women with severe asthma.10 Acute asthmatics treated with corticosteroids since the onset of pregnancy have reported a quarter fewer episodes of acute asthma than those not receiving corticosteroid treatment.8 New research has suggested some different associations between pregnant asthmatics and treatment with inhaled corticosteroids. In contrast to previously held beliefs, recent findings indicate that women treated with corticosteroids experience a smaller number of acute asthma attacks than those not treated with inhaled corticosteroids. Fewer hospital admissions for acute asthma episodes have been positively correlated with pregnant asthmatics that have been treated with inhaled beclomethasone when compared to pregnant asthmatics that have not been treated with an inhaled steroid. In fact, no independent associations were found between inhaled corticosteroid use by pregnant asthmatics and adverse pregnancy outcomes. Rather, it has been proposed that any adverse pregnancy outcomes may be due to the severity of the asthma.7
There are also some proposed risks to the infant due to asthma medication. It has been hypothesized that neonatal hyperbilirubinemia may be a result of drug-induced liver toxicity. Women with a multi-drug regimen appear to be at a higher risk for liver damage. Steroids may be related to the increase in infant hyperbilirubinemia by causing an increased susceptibility to drug-induced hepatotoxicity in the immature infant liver. In addition, women who are taking steroids are generally taking at least two medications.15
Organizations
Despite the possible negative effects some asthma medications may pose, well-controlled asthma can help reduce the risk of adverse outcomes for mother and baby. The National Institutes of Health (NIH) formed the National Asthma Education and Prevention Program (NAEPP) in 1993. The NAEPP has formed procedures for treating asthma during pregnancy. Treatment and maintenance for pregnant asthmatics are very similar to those for nonpregnant asthmatics and include recurring lung function tests, fetal monitoring, maintenance of oxygen saturation above 95%, early administration of systemic corticosteroids, and therapy with repeat doses of inhaled b-agonists. Swift therapeutic involvement at the time of exacerbation is crucial to preventing impaired maternal and fetal oxygenation.6 Cydulka believes that pregnant asthmatic caregivers “should become familiar with the NIH NAEPP Guidelines for the care of pregnant asthmatics and read the medical literature on the subject.”
The Asthma and Allergy Foundation of America (AAFA) has developed an eight-step plan for managing asthma during pregnancy. The AAFA champions the need for the formation of a strong team between the obstetrician and the pulmonologist or respiratory care worker who is treating the asthma. The continuation of regular asthma medication and avoidance of other medications are also recommended. Allergy shots should be continued but not initiated during an asthmatic pregnancy. Flu shots should be administered after the third month of pregnancy and avoidance of people with respiratory infections is recommended. Good control of asthma and daily written records of asthma symptoms are beneficial. Daily monitoring of maternal asthma by the mother and fetal monitoring by the physician during each prenatal visit are valuable. Avoidance of triggers and allergens is crucial. Finally, by not smoking and avoiding those who do, a pregnant asthmatic can reduce the risk of having a severe asthma episode and all of the other non-asthma-related side effects of smoking exposure.9
Pregnant asthmatics and their infants often present with multivariant needs. An environment of teamwork treatment will prove optimal if the same health care provider is not equipped to provide both asthma and obstetric care. Asthma status should be monitored continually. Every prenatal visit provides a wonderful opportunity to administer and review lung function tests.12 Cydulka stresses, “The greatest recent improvement [in pregnant asthmatic maintenance and treatment] is increased awareness on the part of care providers of the importance of aggressive treatment for pregnant asthmatics.”
Lung Function Tests
Office spirometry can be included as a regular aspect of a pregnant woman’s prenatal visit. In cases of pregnant asthmatics who take daily medication, determination of peak flow rates can be included in the examination. Both of these procedures indicate the presence or absence of airway obstruction.12 Lung function tests can be of assistance if complications develop in the future. For example, the ponderal index significantly decreases when pregnant asthmatics move into a higher pulmonary function test quartile.7
The results of the pregnant asthmatic’s lung function tests should be taken into consideration when the fetus is being assessed. Ultrasound, nonstress test, electronic fetal heart rate monitoring, and daily kick charts are tools used to provide an accurate fetal assessment and can begin between 26 and 28 weeks gestation.2,12 The clinician can positively change the oxygenation of the uterus by optimizing maternal pulmonary function tests, manipulating maternal position, treating anemia, maintaining normal uteroplacental blood flow, and giving maternal oxygen therapy. A high-resolution sonogram is recommended between 16 and 18 weeks gestation for all asthmatic women.2
If the obstetrician is not equipped or trained to conduct lung function tests in the office, a clear line of frequent and detailed communication should be established between the obstetrician and the respiratory specialist.12 Cydulka notes, “They [obstetricians] need to be aware that the better control of a pregnant woman’s asthma leads to better outcomes for the pregnancy and the baby. Poor outcomes have been clearly documented to occur in poorly controlled asthmatics. If physicians who are caring for pregnant asthmatics are unfamiliar or uncomfortable with their care, they should refer such patients to a specialist.”
Conclusion
While the rate of preeclampsia does not appear to be influenced by care of asthma management specialists, the likelihood of other complications appears to be lowered. Preterm birth and low birth weight have been reported to be lower when asthmatic mothers are treated by respiratory specialists. Perinatal mortality rates are also lower.7 These findings attest to the important function respiratory specialists can offer to pregnant asthmatics. A strong team of respiratory specialists and obstetricians can help an asthmatic woman have a successful pregnancy with low to no asthma-related problems.
Respiratory workers play a crucial role in the well-being of pregnant asthmatics. However, more work needs to be done. Cydulka states, “We have only scratched the surface in our knowledge of pregnant asthmatic women. We need a more concentrated effort in treatment, maintenance, education, and research.”
Jennifer Vavra is a contributing writer for RT Magazine.
References
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