Allergies and Asthma While Pregnant

Asthma affects nearly 7 percent of pregnant women and, if left untreated, it can cause serious complications for both you and your baby. Preexisting asthma reacts differently with each woman once she is pregnant. Generally speaking, if you had severe asthma before your pregnancy, it will probably get worse while you are pregnant. If it was mild, it will probably improve. In about a third of women, it gets worse; in a third it gets better; and in another third it doesn't change. If your asthma or asthma attacks do become worse, it will probably be between your 24th and 36th weeks.

If you do not treat your asthma while you are pregnant, you may experience high blood pressure, toxemia, and premature delivery. Your baby may have an increased risk of being stillborn, delayed or impaired growth, premature birth, low birth weight, and a low APGAR score at birth.

Although you should not take any medication unless it is absolutely necessary and approved by your doctor, especially during the first trimester, the risks of not treating asthma outweigh the risks of most medications. In general, inhaled medications are preferred because only limited amounts of the drug enter the bloodstream. Medications that have been used for years are also preferable because there is more data supporting their safety. Medications are discouraged during the first trimester when your baby's organs are forming, although defects resulting from medications are rare. Always check with your obstetrician or midwife before taking any new medication and if you start seeing an allergist, be sure he or she knows you are pregnant.

Medications are graded by five classes to indicate their level of safety if used during pregnancy:

• Class A medications are the safest. They have been proven to be safe for pregnant women and their babies.
• Class B medications are considered safe during pregnancy, although definitive study evidence in humans is lacking.
• Class C medications are potentially harmful according to animal studies, although no studies in humans are available.
• Class D medications have been shown to be harmful to human fetuses; however the potential benefits may be acceptable despite the risks. May be used for life-threatening diseases for which safer drugs cannot be used or are ineffective.
• Category X medications show fetal abnormalities in studies on animals or humans. The risk of using the drug in pregnant women clearly outweigh any possible benefit.

Most cell stabilizers such as comolyn sodium help prevent allergic reactions. They are usually available by prescription in the form of eyedrops, nasal sprays, and inhalers. These types of medications fall into category B and are considered safe to use during pregnancy. They are sold under the brand names Intal inhalers, Nasalcrom nasal sprays, and Crolom eyedrops.

Inhaled steroids used to treat asthma caused by environmental allergies are category C drugs. They should only be used if the benefits outweigh the potential risks.

Over-the-counter antihistamines such as chlorpheniramine (sold as Chlortrimetron), diphenhydramine (sold as Benadryl), and loratadine (sold as Claritin) are category B drugs.

The category ratings of prescription antihistamines depend on which drug you take. Fexofenadine (sold as Allegra) is a category C drug, while cetirizine (sold as Zyrtec) is category B. Talk to your doctor about which drug is best for you.

Over-the-counter decongestants such as pseudoephedrine (sold as Sudafed) are category C drugs. Some antihistamines and cold medicines may also contain pseudoephedrine if they say they contain a decongestant. Check the label before taking one of these medications.

There is usually a connection between asthma or allergies, and pollens, molds, animals, house dust mites, and cockroaches. Other non-allergic substances may aggravate asthma, such as tobacco smoke, paint and chemical fumes, strong odors, environmental pollutants (including ozone and smog), and drugs such as aspirin or beta-blockers. Avoiding these allergy and asthma triggers should decrease the frequency and intensity of asthma attacks and allergy symptoms.

Allergy shots are an effective treatment if you continue to experience symptoms despite medication and avoiding allergens. If you were receiving allergy shots before your pregnancy, they can usually be safely continued during your pregnancy, provided you do not develop any adverse reactions. However, it is not recommended that allergy shots be started during pregnancy.

A yearly flu shot is recommended if you have moderate to severe asthma. If you have severe asthma and contract the flu, you may experience serious asthma attacks and can develop pneumonia, which can harm your baby. Some experts recommend that you wait until your second or third trimester to get a flu shot to avoid any possible adverse affects to your baby.