Doctors are very cautious about the use of drugs during the first three months of pregnancy even though most anti-asthmatic medications are considered safe during pregnancy. While theoretically, some medications may contribute to an increased risk to the fetus, it is important to understand that the risk of uncontrolled asthma far outweighs the risks associated with necessary medications. Aerosols and sprays are preferable to oral medication when this treatment option exists because in this form, almost none of the medication entersthe bloodstream and crosses the placenta. Allergy shots may also be continued without adverse affect on pregnancy. Such a reaction, though rare, could be harmful to the fetus.
Pregnancy can effect the relative severity of asthma.
For a fortunate minority, asthma improves during pregnancy. The exact reason for this is unknown, but the increase in the body's cortizone level during pregnancy may be an important cause of the improvement which can occur. Then again, asthma symptoms may be worse during pregnancy. Some women experience gastroesophageal reflux causing belching and heartburn. This reflux, as well as sinus infections and increased stress, may aggravate asthma.