Studies show that when asthma is well controlled, you are less likely to have complications during pregnancy. If your asthma is not under control, it is possible for oxygen to dip to low levels that can cause harm to the baby. Another problem is low birth weight. Poor asthma control could make you more likely to develop preeclampsia, which causes high blood pressure and other symptoms at the end of pregnancy or during childbirth. Preeclampsia is a serious medical condition that can cause kidney, brain, liver or eye damage in the mother, and seizures in the mother or baby.

Pregnant women with asthma should try to control asthma symptoms early, before they are severe. Inhaled corticosteroids can be used for mild or moderate symptoms. Inhaled steroids expose your baby to a lower dose compared with oral steroids, such as prednisone pills. But if your doctor said to use prednisone pills, you should do so. Once your symptoms are under control, you and your doctor can taper your prednisone down over a week or two.

You are right to consider the possible risks of using a drug like prednisone while pregnant. Prednisone can cause many of the same side effects for a baby that it causes for an adult. If it is used for a prolonged period, it could affect the strength of bones, the pattern of fat and muscle shape, and the baby's metabolism. Most of these changes would be temporary. And it's important to note that asthma that is not controlled is a worse problem for the fetus than exposure to prednisone.

If your asthma has been active enough during pregnancy to require prednisone, ask your doctor how you can minimize your asthma triggers. Controlling dust mite exposure and avoiding exposure to mold, animal dander, and second-hand smoke are important ways to control asthma.