Asthma & Pregnancy: Can I Use That Medication?

Pregnancy Impact On Asthma Control and Choice of Medication

Asthma and Pregnancy
Asthma and pregnancy CAN go together, with the right approach. Digital Images / Getty Images

Because asthma is so common a medical condition, it is not surprising that 3 - 8 percent of all pregnancies involve a diagnosis of asthma.

Unlike some conditions where you can stop a medication during pregnancy or during the first part of pregnancy during the time period of greatest risk for teratogenic effects, asthmatics need to take their medication to maintain good control. This leads to a number of questions related to the safety of asthma medications during pregnancy, the impact of the pregnancy on your asthma control, and will asthma make a pregnancy high risk or cause some harm to the baby or yo you?

Asthma Control During Pregnancy

Asthma control in pregnancy can be thought of by a rule of thirds– one-third of pregnant asthmatics experience improved control, a third shows no change, and the final third experience a worsening of their symptoms. In general, your asthma severity before becoming pregnant is related to your asthma severity during pregnancy.

While one might think that as your abdominal girth increases that asthma control would worsen, but it turns out to be just the opposite and asthma is less severe in the last weeks of pregnancy. When asthma control improved it seemed to do so gradually over the pregnancy course. In women whom asthma worsened, worsening was most common between 29–36 weeks of pregnancy. Significant asthma symptoms are uncommon during labor and delivery. Asthma attacks seemed to occur more commonly during the second and third trimester. Finally, the asthma course during pregnancy tends to repeat itself over subsequent pregnancies.

If your asthma improved during pregnancy it tends to improve with future pregnancies and vice versa.

The Impact Of Asthma on Pregnancy

Poorly controlled asthma can lead to all of the following complications:

These complications may result from decreased oxygen levels. Decreased oxygen levels in mom can lead to decreased oxygen levels for your baby and decreased blood flow to the placenta. There are also possible complications from asthma medications.

None of these of the changes related to asthma control or the effect of asthma on pregnancy should be taken to mean that asthmatics should not get pregnant. Good treatment and control will minimize and decrease the risk of these complications.

The more severe your asthma, the more likely you are to have asthma complications.

Asthma Treatment In Pregnancy

Your asthma treatment in pregnancy is not all that different than your treatment in the non-pregnant state. You need an asthma action plan, need to regularly monitor your asthma symptoms, and attempt to avoid triggers. One of the things that makes monitoring a little more difficult in pregnancy is the sensation of shortness of breath many pregnant patients get, especially later in pregnancy.

Coughing and wheezing, however, are never normal symptoms of pregnancy and could be a sign of poor asthma control. As a result, monitoring asthma with peak flows or FEV1 may be a little more reliable in the pregnant patient. A decrease in either of these may suggest an asthma exacerbation.

As with the non-pregnant patient, quitting smoking is important for the pregnant asthmatic. Not only does smoking increase the risk of an asthma exacerbation, but it can make low oxygen levels worse and potentially increase the risk of experiencing one of the previously mentioned complications. Likewise, avoiding other irritants such as dust, dander, and dust mites is an important part of your action plan.

Medications During Pregnancy

Related to asthma treatment in pregnancy, two questions commonly arise related to medications.

1. Do asthma medications have adverse effects on a developing baby?

2. Does pregnancy alter the effectiveness of a particular medication compared to its effectiveness in the non-pregnant state?

Asthma medications during pregnancy have been associated with a number of serious adverse outcomes such as :

  • Miscarriage
  • Death
  • Congenital malformations
  • Decreased growth in-utero
  • Poor development
  • Decreased blood flow to the placenta
  • Increased risk of preterm delivery

However, one should be aware all of these adverse effects are common in pregnancy, even in pregnant women without asthma. For example, congenital anomalies occur in 3% of live births and miscarriages 10–15% of pregnancies. No current asthma drugs are currently labeled Category A by the United States Food and drug Administration. These would be drugs that controlled research studies in pregnant women failed to demonstrate a risk to the fetus in early pregnancy and no evidence of risk later pregnancy. Most asthma drugs are either class B or class C. A class B drug means that animal studies have not demonstrated any fetal risk, but there are no controlled studies in pregnant women. It can also mean that there was some risk identified in animal studies that was not subsequently confirmed in studies of women in the first trimester of pregnancy and no evidence of risk later in pregnancy. In class C risk cannot be ruled out and use should be considered only if the benefits to the fetus outweigh risks. In class D there is positive evidence of risk, but the use of the drug may be acceptable despite the risk.

In general, it is felt that active treatment to maintain good asthma control and prevent exacerbations outweighs the risks of most regularly used medications for the treatment of asthma. Albuterol, beclomethasone, and budesonide have all been used in studies of pregnant asthmatics and the studies all had reassuring outcomes. On the other hand, the studies with oral prednisone have not been as reassuring. There are also a number of drugs that have very little human experience in pregnant patients.

SABAs. Short-acting beta agonists provide quick relief for asthma symptoms such as:

While extremely high doses of SABAs have shown teratogenic effects in animals, there is not data clearly demonstrating teratogenic effects in humans. Studies have shown have shown few if any problems with albuterol. However, a couple of very small studies demonstrated gastroschisis or a birth defect in which an infant is born with some or all of his/her intestines on the outside of the abdomen due to an abnormal opening in the abdominal muscle wall. One problem with some of the outcome studies demonstrating a potential harm is that SABA use is associated with poorly controlled asthma which can lead to many of the previously described complications.

Systemic beta–adrenergic agonists are sometimes used to prevent premature labor. Rather than inhaled these drugs are given through an IV. The most common side effects seen wit this route of administration is hyperglycemia or elevated blood sugars. When infants are born they sometimes have elevated heart rates, tremors, and low blood sugars as a result of maternal treatment. All of these side effects in the newborn are treatable and usually, reverse fairly quickly so they are not contraindicated.

LABAs. Experience with LABAs and pregnancy is much less significant than with SABAs. Based on currently available experience which includes both human and animal studies, it does not seem that salmeterol or formoterol increases the risk of congenital anomalies. There is more direct human experience with salmeterol. As a result, it is reasonable if a woman becomes pregnant to continue a LABA that was needed for asthma control in the pre-pregnant state. The risk of congenital malformations with a lower dose combination of LABA/ inhaled steroid appears to be similar to a medium or high dose ICS monotherapy.

Epinephrine. Because of the risk of decreased blood flow to the placenta, the Working Group on Pregnancy and Asthma recommend this drug only be used in the setting of anaphylaxis.

Oral steroids. Oral steroids are commonly used in pregnancy for a variety of conditions other than asthma. Some of the concerns regarding their use include increased the risk of prematurity, congenital malformations (mostly cleft palate), pregnancy-induced hypertension, gestational diabetes, low birth weight, and neonatal adrenal insufficiency. There are few definitive answers. For example, some studies have shown an increased risk of cleft palate and others have not. The evidence demonstrating premature birth among women receiving steroids throughout pregnancy is a little stronger. Finally, hypertension and elevated glucose levels are known complication and therefore, not surprising. So it really comes down to risks. There is a significant risk to mother and fetus related to poor asthma control. The risks of severely uncontrolled asthma would seem to outweigh the potential risks of steroids for most patients.

Inhaled steroids. The safety data for inhaled steroids on pregnancy, like that for non-pregnant patients, is much more reassuring. A registry study of the inhaled steroid budesonide in Swedish women showed no increased risk of malformations compared to the general population. The study also showed no complications related to fetal growth, mortality, or prematurity. Based on these findings it is the only inhaled steroids currently with a category B rating. In another database like study, fluticasone showed no increases in congenital malformations compared to other inhaled steroids. Two randomized controlled trials demonstrated improved lung function and decreased rates of readmission.

Leukotriene modifiers. Like LABAs, this class of drug has only a small clinical experience to date, but the data with montelukast is growing. Unpublished data from the Merck Pregnancy Registry and a prospective, controlled trial indicate that rates of congenital malformations do not appear to be different from the general population. As a result, patients needing a leukotriene modifier would be better served by montelukast until more data is available from other agents.

Anti-immunoglobulin E. Monoclonal anti-immunoglobulin E antibody or omalizumab is approved for patients with poorly controlled asthma with elevated levels of IgE despite the use of inhaled steroids. While not formally evaluated in in clinical studies, the rates of complications such as miscarriage, preterm birth, small-for-gestational-age infants, and congenital anomalies appear to be similar to other studies of pregnant asthmatics. There is not currently enough data to make a recommendation for its use in pregnancy.

Methylxanthines. There is extensive clinical experience with theophylline and aminophylline in pregnancy. While theses drugs are clinically safe, their metabolism is changed significantly in pregnancy and levels must be monitored. The narrow therapeutic range is very small which makes treatment in non-pregnant patients difficult. Further, just as in non-pregnant patients, inhaled steroids are more effective for asthma control. As a result, these drugs are best thought of as add-on agents if control is not able to be achieved with inhaled steroids.

Immunotherapy. While it is not recommended to start immunotherapy during pregnancy, it does not appear these treatments create additional risk to mother or fetus so can be continued during pregnancy.


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