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Sunday, August 16, 2009

Asthma and Pregnancy:

Does Asthma Get Worse During Pregnancy?

Asthma tends to follow a “rule of thirds” during pregnancy. This means that one-third of pregnant asthmatics get better, one-third get worse, and one-third remain the same as prior to pregnancy. Women who follow one pattern with one pregnancy tend to have a similar pattern with future pregnancies.

It is common for severe asthmatics to get worse during pregnancy, while those with mild asthma tend to improve. The majority of asthma exacerbations occur during 24 to 36 weeks of gestation; only rarely does the asthma worsen significantly during labor and delivery. Usually asthma returns to its pre-pregnancy state within 3 months of delivery.

What are the Risks of Asthma During Pregnancy?

Asthma is the most frequent chronic respiratory disease affecting pregnancy, occurring in approximately 4% of pregnant women. There are numerous complications that affect mother and baby if the asthma is uncontrolled. After all, the fetus is relying on the mother’s lungs for oxygen. If the mother’s oxygen level is low because she is having as asthma attack, then the fetus is not likely getting enough oxygen either.

Maternal complications of uncontrolled asthma include:

    • High blood pressure
    • Toxemia of pregnancy
    • Uterine hemorrhage
    • Need for caesarian section

Fetal complications of uncontrolled asthma in the mother include

    • Risk of stillbirth
    • Premature birth
    • Low birth weight
    • Growth Retardation

How Should a Pregnant Asthmatic Be Monitored?

It is recommended that all pregnant women with asthma are followed closely by an asthma specialist during their pregnancy. This may include monthly evaluations of asthma history and lung function testing. An obstetrician may plan to perform more frequent ultrasound examinations in women with under-controlled asthma. It is important to tell your obstetrician if you have asthma.

What Medication is Safe to Take During Pregnancy?

According to the Food and Drug Administration (FDA), no asthma drugs are considered completely safe in pregnancy. This is because no pregnant woman would want to sign-up for a medication safety study while she is pregnant. Therefore, the FDA has assigned risk categories to medications based on use in pregnancy.

Pregnancy category “A” medications are medications in which there are good studies in pregnant women showing the safety of the medication to the baby in the first trimester. There are very few medications in this category, and no asthma medications. Category “B” medications show good safety studies in pregnant animals but there are no human studies available. Pregnancy category “C” medications may result in adverse effects on the fetus when studied in pregnant animals, but the benefits of these drugs may out weight the potential risks in humans. Category “D” medications show clear risk to the fetus, but there may be instances in which the benefits outweigh the risks in humans. And finally, category “X” medications show clear evidence of birth defects in animals and/or human studies and should not be used in pregnancy.

Before any medication is taken during pregnancy, the doctor and patient must have a risk/benefit discussion. This means that the benefits of the medication should be weighed against the risks – and the medication should only be taken if the benefits outweigh the risks.

What Asthma Medication is Safe to Take During Pregnancy?

Again, safety of asthma medications during pregnancy is a determination of risks and benefits to be made by a physician. However, the professional organizations of obstetricians (ACOG) and allergists (ACAAI) have published guidelines on the management of asthma during pregnancy. In general, treatment of asthma during pregnancy is not different from guidelines for asthma in non-pregnancy. This is also true for recommended medications based on level of severity of asthma.

Rescue medications for acute asthma symptoms include inhaled beta-agonists such as albuterol. While these medications are all category “C”, the experience of these drugs in pregnant women is enormous and shows no evidence of adverse effects on the baby, either during pregnancy or breastfeeding.

Controller medications for persistent asthma include inhaled steroids, which are the preferred method to control the underlying inflammation in asthma. Other medications in this group include long-acting beta-agonists (used in combination with inhaled steroids such as in Advair®) theophylline, cromolyn, nedocromil, and leukotriene blocking medications (such as montelukast).

The preferred inhaled steroids include beclomethasone (category “C”) and budesonide (category “B”). However, ACOG/ACAAI considers it reasonable to continue another types of inhaled steroid during pregnancy if the mother was well-controlled with using that medication.

A combination product such as Advair® may be required in patients with more severe asthma. These medications combine inhaled steroids with a long-acting beta-agonist (albuterol-like medication), and is used as a controller therapy. Patients still require albuterol for “as needed” or rescue use. Long-acting beta-agonists, such as salmeterol, are considered to have safety comparable to albuterol.

Other controller medications such as theophylline (category “C”) and cromolyn, nedrocromil and the leukotriene blocking drugs (all category “B”) are reasonable to continue during pregnancy if the mother has had good benefit from the medications prior to pregnancy. However, none of these medications would be considered a “first choice” to start during pregnancy.