Corticosteroids are beneficial for preterm babies, but even a single dose of steroids may have some short-term adverse effects on you. Although it doesn't happen often, corticosteroids can raise your blood sugar to levels that require you to take insulin for a little while even if you don't have diabetes. If you do have diabetes or gestational diabetes, being given corticosteroids may require you to increase your insulin dosage.
Another uncommon effect of corticosteroids occurs when they're combined with other medications (specifically, tocolytics) to stop preterm labor. In this combination, they can raise your risk of developing pulmonary edema, a condition in which fluid builds up in your lungs. If you're taking both tocolytic medications and corticosteroids, you'll need to be watched especially carefully even though the risk of pulmonary edema is still pretty low.